A-J

Glossary of Toxicology Terms

#A - #B - #C - #D - #E - #F - #G - #H - #I - #J -
K-Z

Key

AN: antonym

RT: related term

SN: synonym

A


abatement: Reducing the degree or intensity of, or eliminating, pollution. (#CEHN)

abiological: See SN abiotic. (#IUPAC)

abiotic: Not associated with living organisms. (#IUPAC)

abiotic transformation: Process in which a substance in the environment is modified by nonbiological mechanisms. (#IUPAC)

absolute lethal concentration (LC100): Lowest concentration of a substance, in an environmental medium, that kills 100 percent of test organisms or species under defined conditions. This value is dependent on the number of organisms used in its assessment.
WHO, 1979 (#IUPAC)

absolute lethal dose (LD100): Lowest amount of a substance that kills 100 percent of test animals under defined conditions. This value is dependent on the number of organisms used in its assessment. (#IUPAC)

absorbed dose (of a substance): Amount of a substance absorbed into an organism or into organs and tissues of interest. (#IUPAC)

absorbed dose (of radiation): Energy imparted to matter in a suitably small element of volume by ionizing radiation divided by the mass of that element of volume. The SI unit for absorbed dose is joule per kilogram (J kg-1) and its special name is gray (Gy).
ISO, 1972 (#IUPAC)

absorption (biological): Process of active or passive transport of a substance into an organism: in the case of a mammal or human being, this is usually through the lungs, gastrointestinal tract, or skin. (#IUPAC)

absorption (in colloid and surface chemistry): Process whereby, when two phases are brought into contact, a particular component is transferred from one phase to the other.
PAC,1972 (#IUPAC)

absorption (of radiation): Phenomenon in which radiation transfers some or all of its energy to matter which it traverses.
ISO, 1972 (#IUPAC)

absorption coefficient (in biology): Ratio of the absorbed amount (uptake) of a substance to the administered amount (intake): for exposure by way of the respiratory tract, the coefficient is the ratio of the absorbed amount to the amount of the substance (usually particles) deposited (adsorbed) in the lungs.
RT absorbed dose
SN absorption factor
IRPTC, 1982 (#IUPAC)

abuse (of drugs, substances, Solvents - Chemical Profiles and External Links etc.): Improper use of drugs or other substances. (#IUPAC)
RT "glue sniffing", solvent abuse, "solvent sniffing"

acaricide: Substance intended to kill mites, ticks, or other Acaridae. (#IUPAC)

acceptable daily intake (ADI): Estimate of the amount of a substance in food or drinking water, expressed on a body-mass basis (usually mg/kg body weight), which can be ingested daily over a lifetime by humans without appreciable health risk. For calculation of the daily intake per person, a standard body mass of 60 kg is used. ADI is normally used for food additives (tolerable daily intake is used for contaminants).(WHO, 1991)
RT tolerable daily intake (#IUPAC)

acceptable daily intake (ADI) not allocated: See SN no acceptable daily intake allocated (#IUPAC)

acceptable residue level of an antibiotic: Acceptable concentration of a residue which has been established for an antibiotic found in human or animal foods. (#IUPAC)

acceptable risk: Probability of suffering disease or injury which is considered to be sufficiently small to be "negligible."
PS tolerable risk
RT accepted risk, negligible risk, risk de minimis (#IUPAC)

accepted risk: Probability of suffering disease or injury which is accepted by an individual. (#IUPAC)

accidental exposure: Unintended contact with a substance or change in the physical environment (including for example radiation) resulting from an accident. (#IUPAC)

acclimatization (biological):
1. Processes, including selection and adaptation, by which a population of micro-organisms develops the ability to degrade a substance, or develops a tolerance to it.
2. In animal tests - allowing an animal to adjust to its environment prior to undertaking a study. (#IUPAC)

accumulation: Successive additions of a substance to a target organism, or organ, or to part of the environment, resulting in an increasing amount or concentration of the substance in the organism, organ, or environment.
WHO, 1989a (#IUPAC)

accuracy: Quantity referring to the differences between the mean of a set of results or an individual result and the value which is accepted as the true or correct value for the quantity measured.
Gold, Loening, McNaught and Sehmi, 1987
RT precision. (#IUPAC)

ACGIH: See "American Conference of Governmental Industrial Hygienists"

acidosis: Pathological condition in which the hydrogen ion substance concentration of body fluids is above normal and hence the pH of blood falls below the reference interval.
AN alkalosis. (#IUPAC)

action level:
1. Concentration of a substance in air, soil, water or other defined medium at which specified emergency counter-measures, such as the seizure and destruction of contaminated materials, evacuation of the local population or closing down the sources of pollution, are to be taken.
2. Concentration of a pollutant in air, soil, water or other defined medium at which some kind of preventive action (not necessarily of an emergency nature) is to be taken. (#IUPAC)

active ingredient: In any pesticide product, the component that kills, or otherwise controls, target pests. Pesticides are regulated primarily on the basis of active ingredients. (1) (CEHN)
activation: See NT bioactivation. (#IUPAC)

acute:
1. Short-term, in relation to exposure or effect. In experimental toxicology, "acute" refers to studies of two weeks or less in duration (often less than 24 h).
AN chronic
2. In clinical medicine, sudden and severe, having a rapid onset. (#IUPAC)

acute effect: Effect of short duration and occurring rapidly (usually in the first 24 h or up to 14 d) following a single dose or short exposure to a substance or radiation. (#IUPAC)

acute exposure: Contact with a substance that occurs once or for only a short time (up to 14 days) compare with intermediate duration exposure and chronic exposure. (#ATSDR)

acute toxicity:
1. Adverse effects occurring within a short time (usually up to 14 d) after administration of a single dose (or exposure to a given concentration) of a test substance or after multiple doses (exposures), usually within 24 h.
2. Ability of a substance to cause adverse effects within a short time of dosing or exposure.
AN chronic toxicity.
(International)

acute toxicity test: Experimental animal study to determine what adverse effects occur in a short time (usually up to 14 d) after a single dose of a substance or after multiple doses given in up to 24h.
RT limit test, median lethal dose (LD50) (#IUPAC)

adaptation:
1. Change in an organism, in response to changing conditions of the environment (specifically chemical), which takes place without any irreversible disruptions of the given biological system and without exceeding normal (homeostatic) capacities of its response.
2. Process by which an organism stabilizes its physiological condition after an environmental change.
RT acclimatization
(#IUPAC)

added risk: Difference between the incidence of an adverse effect in a treated group (of organisms or a group of exposed humans) and a control group (of the same organisms or the spontaneous incidence in humans).
IRIS, 1986 (#IUPAC)

addiction: Surrender and devotion to the regular use of a medicinal or pleasurable substance for the sake of relief, comfort, stimulation, or exhilaration which it affords; often with craving when the drug is absent.
PS dependence (#IUPAC)

additive effect: Consequence which follows exposure to two or more physico-chemical agents which act jointly but do not interact: commonly, the total effect is the simple sum of the effects of separate exposure to the agents under the same conditions. Substances of simple similar action may show dose or concentration addition.
RT antagonism, combined effect of poisons, potentiation, synergism (#IUPAC)

adduct: New chemical species AB, each molecular entity of which is formed by direct combination of two separate molecular entities A and B in such a way that there is no change in connectivity of atoms within their moieties A and B. Stoichiometries other than 1:1 are also possible. An intramolecular adduct can be formed when A and B are groups contained within the same molecular entity.
Gold, Loening, McNaught and Sehmi, 1987 (#IUPAC)

adenocarcinoma: Malignant tumour originating in glandular epithelium or forming recognizable glandular structures.
RT adenoma (#IUPAC)

adenoma: Benign tumour occurring in glandular epithelium or forming recognizable glandular structures.
RT adenocarcinoma (#IUPAC)

adjuvant:
1. In pharmacology, a substance added to a drug to speed or increase the action of the main component.
2. In immunology, a substance (such as aluminium hydroxide) or an organism (such as bovine tuberculosis bacillus) which increases the response to an antigen. (#IUPAC)

administration (of a substance): Application of a known amount of a substance to an organism in a reproducible manner and by a defined route (#IUPAC)

adrenergic: See SN sympathomimetic. (#IUPAC)

adsorption: Enrichment (positive adsorption, or briefly adsorption) of one or more components in an interfacial layer.
Gold, Loening, McNaught and Sehmi, 1987 (#IUPAC)

adverse effect: Change in morphology, physiology, growth, development or lifespan of an organism which results in impairment of functional capacity or impairment of capacity to compensate for additional stress or increase in susceptibility to the harmful effects of other environmental influences.
After IPCS, 1978 (#IUPAC)

adverse event: Occurrence which causes an adverse effect. (#IUPAC)

aerobe: Organism which needs molecular oxygen for respiration and hence for growth and life.
After Nagel et al. (eds), 1991 (#IUPAC)

aerobic: Requiring molecular oxygen. (#IUPAC)

aerodynamic diameter (of a particle): Diameter of a spherical particle of unit density which has the same settling velocity in air as the particle in question.
IPCS, 1978 (#IUPAC)

aerosol: Dispersion of liquid or solid material in a gas.
Gold, Loening, McNaught and Sehmi, 1987 (#IUPAC)

aetiology:
1. Science dealing with the cause or origin of disease.
2. In individuals, the cause or origin of disease.
RT epidemiology
(International)

after-effect of a poison: Ability of a poison to produce a change in an organism after cessation of contact. (#IUPAC)

age sensitivity: Quantitative and qualitative age dependence of an effect.
IRPTC, 1982 (#IUPAC)

Ag & Mkts: See "New York State Department of Agriculture and Markets" (#Glossary)

AG's Office: Attorney General's Office. See "New York State Department of Law" (#Glossary)

Agency for Toxic Substances and Disease Registry (ATSDR): ATSDR is part of the U.S. Department of Health and Human Services. As mandated by the federal superfund law, the agency assesses health risks from hazardous waste sites on the National Priority List. ATSDR determines if additional health studies are needed at these sites, provides health advisories and publishes toxicological profiles on chemicals found at hazardous waste sites. ATSDR also maintains exposure registries of people exposed to certain substances. (#Glossary)

agonist: Substance which binds to cell receptors normally responding to naturally occurring substances and which produces a response of its own.
AN antagonist. (#IUPAC)

air particulates: Total suspended particulate matter found in the atmosphere as solid particles or liquid droplets. Chemical composition of particulates varies widely, depending on location and time of year. Airborne particulates include windblown dust, emissions from industrial processes, smoke from the burning of wood and coal, and motor vehicle or non-road engine exhausts. (1) ([#CEHN)

agricultural pollution: Farming wastes, including runoff and leaching of pesticides and fertilizers; erosion and dust from plowing; improper disposal of animal manure and carcasses; crop residues, and debris. (1) (#CEHN)

air pollutants, hazardous: Air pollutants which are not covered by ambient air quality standards but which, as defined in the Clean Air Act, may reasonably be expected to cause or contribute to irreversible illness or death. Such pollutants include asbestos, beryllium, mercury, benzene, coke-oven emissions, radionuclides, and vinyl chloride. (1) (#CEHN)

air pollution: Presence of substances in the atmosphere resulting either from human activity or natural processes, in sufficient concentration, for a sufficient time and under circumstances such as to interfere with comfort, health or welfare of persons or to harm the environment.
ISO, 1980
BT pollution

air pollution control system:
1. Network of organizations which monitor air pollution
2. Group of measures or processes used to minimize or prevent air pollution
RT air pollution,pollution
(#IUPAC)

Air quality standards: The level of pollutants prescribed by regulations that may not be exceeded during a given time in a defined area.(1) (#CEHN)

Air toxics: Any air pollutant for which a national ambient air quality standard (NAAQS) does not exist (i.e., excluding ozone, carbon monoxide, PM-10, sulfur dioxide, nitrogen oxide) that may reasonably be anticipated to cause cancer, developmental effects, reproductive dysfunctions, neurological disorders, heritable gene mutations, or other serious or irreversible chronic or acute health effects in humans. (1) (CEHN)

albuminuria: Presence of albumin, derived from plasma, in the urine.
RT microalbuminuria, proteinuria (#IUPAC)

algicide: Substance intended to kill algae. (#IUPAC)

alkalosis: Pathological condition in which the hydrogen ion substance concentration of body fluids is below normal and hence the pH of blood rises above the reference interval.
AN acidosis (#IUPAC)

alkylating agent: Substance which introduces an alkyl substituent into a compound. (#IUPAC)

allele: One of several alternate forms of a gene which occur at the same relative position (locus) on homologous chromosomes and which become separated during meiosis and can be recombined following fusion of gametes.
RT gametes, meiosis
Nagel et al. (eds), 1991 (#IUPAC)

allergen: Antigenic substance capable of producing immediate hypersensitivity.
RT allergy, antigen, hypersensitivity (#IUPAC)

allergy: Symptoms or signs occurring in sensitized individuals following exposure to a previously encountered substance (allergen) which would otherwise not cause such symptoms or signs in non-sensitized individuals. The most common forms of allergy are rhinitis, urticaria, asthma, and contact dermatitis
RT immune response, hypersensitivity (#IUPAC)

all-or-none effect: See SN quantal effect.
RT stochastic effect (#IUPAC)

alopecia: Baldness; absence or thinning of hair from areas of skin where it is usually present. (#IUPAC)

alternative fuels: Substitutes for traditional liquid, oil-derived motor vehicle fuels like gasoline and diesel. Includes methanol, ethanol, compressed natural gas, and others. (#CEHN)

alternative technology: Approach that aims to use resources efficiently or to substitute resources in order to do minimum damage to the environment. This approach permits a large degree of personal control over the technology. (#CEHN)

alveolus (pulmonary), -i pl., -ar adj.: Terminal air sac of the lung where gas exchange occurs. (#IUPAC)

ambient: Surrounding (applied to environmental media such as air, water, sediment or soil). (#IUPAC)

ambient monitoring: Continuous or repeated measurement of agents in the environment to evaluate ambient exposure and health risk by comparison with appropriate reference values based on knowledge of the probable relationship between exposure and resultant adverse health effects.
After Berlin, Yodaiken, and Henman, 1984
RT biological monitoring, environmental monitoring, monitoring (#IUPAC)

ambient standard: See SN environmental quality standard. (#IUPAC)

American Conference of Governmental Industrial Hygienists (ACGIH): ACGIH is a professional society of government workers and educators who work to promote occupational safety and health. The organization publishes recommendations on ventilation, air sampling and air concentration guidelines (threshold limit values or TLVS) designed to control exposure of workers to chemicals, noise and radiation in the workplace. (#Glossary)

ames test: In vitro test for mutagenicity using mutant strains of the bacterium Salmonella typhimurium which cannot grow in a given histidine-deficient medium: mutagens can cause reverse mutations which enable the bacterium to grow on the medium. The test can be carried out in the presence of a given microsomal fraction (S-9) from rat liver to allow metabolic transformation of mutagen precursors to active derivatives. (#IUPAC)

amplification (of genes): See gene amplification. (#IUPAC)

anabolism: Biochemical processes by which smaller molecules are joined to make larger molecules.
AN catabolism (#IUPAC)

anemia: Condition in which there is a reduction in the number of red blood cells or amount of haemoglobin per unit volume of blood below the reference interval for a similar individual of the species under consideration, often causing pallor and fatigue. (#IUPAC)

anaerobe: Organism which does not need molecular oxygen for life. Obligate (strict) anaerobes grow only in the absence of oxygen. Facultative anaerobes can grow either in the presence or in the absence of molecular oxygen.
Nagel et al. (eds), 1991
AN aerobe ((#IUPAC)

anaerobic: Not requiring molecular oxygen (#IUPAC)

anaesthetic: Substance which produces loss of feeling or sensation: general anaesthetic produces loss of consciousness; local or regional anaesthetic renders a specific area insensible to pain. (#IUPAC)

analgesic: Substance which relieves pain, without causing loss of consciousness. (#IUPAC)

analogue metabolism: Process by which a normally non-biodegradable compound is biodegraded in the presence of a structurally similar compound which can induce the necessary enzymes. (#IUPAC)

analytic study (in epidemiology): Hypothesis-testing method of investigating the association between a given disease or health state or other dependent variable and possible causative factors. In an analytic study, individuals in the study population are classified according to absence or presence (or future development) of specific disease and according to attributes which may influence disease occurrence. (#IUPAC)

Attributes may include age, race, sex, other disease(s), genetic, biochemical, and physiological characteristics, economic status, occupation, residence, and various aspects of the environment or personal behaviour. (#IUPAC)

Three types of analytic study are: cross-sectional (prevalence), cohort (prospective), and case control (retrospective). Last, 1988 (#IUPAC)

anaphylaxis: Severe allergic reaction occurring in a person or animal exposed to an antigen or hapten to which they have previously been sensitized.
RT antigen, hapten (#IUPAC)

anaplasia: Loss of normal cell differentiation, a feature characteristic of most malignancies .

RT [malignancy|http://sis.nlm.nih.gov/enviro/glossarym.html#malignancy (#IUPAC)

anemia: See anaemia. (#IUPAC)

aneuploid: Cell or organism with missing or extra chromosomes or parts of chromosomes. (#IUPAC)

animal studies: Investigations using animals as surrogates for humans with the expectation that the results are pertinent to humans. (1) #(CEHN)

anoxia: Strictly total absence of oxygen but sometimes used to mean decreased oxygen supply in tissues. (#IUPAC)

*antagonism: Combined effect of two or more factors which is smaller than the solitary effect of any one of those factors. In bioassays, the term may be used when a specified response is produced by exposure to either of two factors but not by exposure to both together. (#IUPAC)
RT synergism

antagonist:
1. Substance that reverses or reduces the effect induced by an agonist.
2. Substance that attaches to and blocks cell receptors that normally bind naturally occurring substances.
AN agonist (#IUPAC)

antagonistic effect : A biologic response to exposure to multiple substances that is less than would be expected if the known effects of the individual substances were added together compare with additive effect and synergistic effect. (ATSDR)
anthelmint(h)ic

anthelmint(h)ic: Substance intended to kill parasitic intestinal worms, such as helminths
SN antihelminth (#IUPAC)

anthracosis (coal miners' pneumoconiosis): Form of pneumoconiosis caused by accumulation of carbon deposits in the lungs due to inhalation of smoke or coal dust. (#IUPAC)

anthropogenic: Caused by or influenced by human activities. (#IUPAC)

anti-adrenergic: See SN sympatholytic. (#IUPAC)

antibiotic: Substance produced by, and obtained from, certain living cells (especially bacteria, yeasts and moulds), or an equivalent synthetic substance, which is biostatic or biocidal at low concentrations to some other form of life, especially pathogenic or noxious organisms. (#IUPAC)

antibody: Protein molecule produced by the immune system (an immunoglobulin molecule) which can bind specifically to the molecule (antigen or hapten) which induced its synthesis.
RT antigen, hapten,[ immunoglobulin|http://sis.nlm.nih.gov/enviro/glossaryi.html#immunoglobulin] (#IUPAC)

anticholinergic:
1. adj., Preventing transmission of parasympathetic nerve impulses.
2. n., Substance which prevents transmission of parasympathetic nerve impulses. (#IUPAC)

anticholinesterase: See SN cholinesterase inhibitor (#IUPAC)

anticoagulant: Substance which prevents clotting. (#IUPAC)

antidote: Substance capable of specifically counteracting or reducing the effect of a potentially toxic substance in an organism by a relatively specific chemical or pharmacological action. (#IUPAC)

antigen: Substance or a structural part of a substance which causes the immune system to produce specific antibody or specific cells and which combines with specific binding sites (epitopes) on the antibody or cells.
After Nagel et al. (eds), 1991
RT antibody, epitope (#IUPAC)

antihelminth: See SN anthelmint(h)ic (#IUPAC)

antimetabolite: Substance, structurally similar to a metabolite, which competes with it or replaces it, and so prevents or reduces its normal utilization. (#IUPAC)

antimycotic: Substance used to kill a fungus or to inhibit its growth.
SN fungicide (#IUPAC)

antipyretic: Substance which relieves or reduces fever. (#IUPAC)

antiresistant: Substance used as an additive to a pesticide formulation in order to reduce the resistance of insects to the pesticide.
IRPTC, 1982 (#IUPAC)

antiserum: Serum containing antibodies to a particular antigen either because of immunization or after an infectious disease. (#IUPAC)

aphasia: Loss or impairment of the power of speech or writing, or of the ability to understand written or spoken language or signs, due to a brain injury or disease (#IUPAC)

aphicide: Substance intended to kill aphids
BT insecticide (#IUPAC)

aphid: Common name for a harmful plant parasite in the family Aphididae: some species are vectors of plant virus diseases (International)

aplasia: Lack of development of an organ or tissue, or of the cellular products from an organ or tissue (#IUPAC)

apoptosis: Physiological process of programmed tissue death (and disintegration) associated with normal development in animals
RT necrosis (#IUPAC)

applied research: An investigative study in which the results are used in actual practice.(2) (#CEHN)

aquifer: An underground source of water. This water may be contained in a layer of rock, sand or gravel. (#Glossary)

arboricide: Substance intended to kill trees and shrubs (#IUPAC)

area source: Widespread origin of emissions
RT point source (#IUPAC)

argyria: Pathological condition characterized by grey-bluish or black pigmentation of tissues (such as skin, retina, mucous membranes, internal organs) caused by the accumulation of metallic silver, due to reduction of a silver compound which has entered the organism during (prolonged) administration or exposure
SN argyrosis (#IUPAC)

argyrosis: See SN argyria (#IUPAC)

arrhythmia: Any variation from the normal rhythm of the heartbeat (#IUPAC)

artifact: Finding or product of experimental or observational techniques that is not properly associated with the system being studied (#IUPAC)

arteriosclerosis: Hardening and thickening of the walls of the arteries (#IUPAC)

arthralgia: Pain in a joint (#IUPAC)

arthralgia saturnia: Pain in a joint resulting from lead poisoning (#IUPAC)

arthritis: Inflammation of a joint, usually accompanied by pain and often by changes in structure (#IUPAC)

asbestos abatement: Procedures to control fiber release from asbestos-containing materials in a building or to remove them entirely, including removal, encapsulation, repair, enclosure, encasement, and operations and maintenance programs.(1) (#CEHN)

asbestosis: Form of pneumoconiosis caused by inhalation of asbestos fibers
BT pneumoconiosis (#IUPAC)

ascaricide: Substance intended to kill roundworms (Ascaridae) (#IUPAC)

asphyxia: Condition resulting from insufficient intake of oxygen: symptoms include breathing difficulty, impairment of senses, and, in extreme, convulsions, unconsciousness and death (#IUPAC)

asphyxiant: Substance that blocks the transport or use of oxygen by living organisms (#IUPAC)

assay:
1. Process of quantitative or qualitative analysis of a component of a sample
2. Results of a quantitative or qualitative analysis of a component of a sample
(#IUPAC)

assessment of exposure: See NT biological assessment of exposure (#IUPAC)

asthenia: Weakness; lack or loss of strength (#IUPAC)

asthma: Chronic respiratory disease characterised by bronchoconstriction, excessive mucus secretion and oedema of the pulmonary alveoli, resulting in difficulty in breathing out, wheezing, and cough (#IUPAC)

astringent:
1. Adj. Causing contraction, usually locally after topical application
2. N. Substance causing cells to shrink, thus causing tissue contraction or stoppage of secretions and discharges; such substances may be applied to skin to harden and protect it
(#IUPAC)

ataxia: Unsteady or irregular manner of walking or movement caused by loss or failure of muscular coordination (#IUPAC)

atherosclerosis: Pathological condition in which there is thickening, hardening, and loss of elasticity of the walls of blood vessels, characterized by a variable combination of changes of the innermost layer consisting of local accumulation of lipids, complex carbohydrates, blood and blood components, fibrous tissue and calcium deposits. In addition, the outer layer becomes thickened and there is fatty degeneration of the middle layer (#IUPAC)

atrophy: Wasting away of the body or of an organ or tissue (#IUPAC)

ATSDR: See "Agency for Toxic Substances and Disease Registry." (#Glossary)

Attainment area: An area considered to have air quality as good as or better than the national ambient air quality standards as defined in the Clean Air Act. An area may be an attainment area for one pollutant and a non-attainment area for others. (#CEHN)

attenuation (in genetics): Regulation of gene expression in bacteria by premature termination of transcription of a biosynthetic operon (#IUPAC)

Attorney General's Office: See "New York State Department of Law." (#Glossary)

attractant: Substance used to attract animals with the aim of killing or sterilizing them
BT pheromone (#IUPAC)

attributable risk: Difference between the risk of exhibiting a certain adverse effect in the presence of a substance and the same risk in the absence of the substance
BT risk
Last, 1988 (#IUPAC)

autoimmune disease: Pathological condition resulting when an organism produces antibodies or specific cells which bind to constituents of its own tissues (autoantigens) and cause tissue injury: examples of such disease may include rheumatoid arthritis, myasthenia gravis, and scleroderma
RT allergy, antibody, antigen, hypersensitivity, immune response (#IUPAC)

autophagosome: Membrane-bound body (secondary lysosome) in which parts of the cell are digested (#IUPAC)

autopsy: Post-mortem examination of the organs and body tissue to determine cause of death or pathological condition
RT biopsy
SN necropsy (#IUPAC)

auxotroph: Organism unable to synthesize an organic molecule which is required for its growth: when the compound is given to the organism with the other nutrients it requires, growth of the organism may occur (#IUPAC)

auxotrophy: Inability of a micro-organism to synthesize a particular organic compound required for its growth
Nagel et al. (eds), 1989 (#IUPAC)

avicide: Substance intended to kill birds (#IUPAC)

axenic animal: See SN germ free animal (#IUPAC)

B


background level: A typical level of a chemical in the environment. Background often refers to naturally occurring or uncontaminated levels. Background levels in one region of the state may be different than those in other areas. (#Glossary)

back-mutation: Process which reverses the effect of a mutation which had inactivated a gene; thus it restores the wild phenotype.
RT phenotype. (#IUPAC)

bacteria: (Singular: bacterium) Microscopic living organisms that can aid in pollution control by metabolizing organic matter in sewage, oil spills or other pollutants. However, bacteria in soil, water or air can also cause human, animal and plant health problems. (#CEHN)

bactericide: Substance intended to kill bacteria. (#IUPAC)

bagassosis: Lung disease caused by the inhalation of dust from sugar-cane residues. (#IUPAC)

base pairing: Linking of the complementary pair of polynucleotide chains of nucleic acids by means of hydrogen bonds between complementary purine and pyrimidine bases, adenine with thymine or uracil, cytosine with guanine. (#IUPAC)

B-cell: See B lymphocyte. (#IUPAC)\
bedrock: The solid rock underneath surface soils (#Glossary)

benefit: Advantage to or improvement in condition of an individual or a population (#IUPAC)

benign:
1. Of a disease, producing no persisting harmful effects.
2.Tumor which does not invade other tissues (metastasize), having lost growth control but not positional control. (#IUPAC)

berylliosis: See SN beryllium disease (#IUPAC)

beryllium disease: Serious and usually permanent lung damage resulting from chronic inhalation of beryllium. (#IUPAC)

bias: Deviation of results or inferences from the truth, or processes leading to such deviation. Any trend in the collection, analysis, interpretation, publication, or review of data which can lead to conclusions which are systematically different from the truth. Among the ways in which deviation from the truth can occur are the following:
1. Systematic (one-sided) variation of measurements from the true values
SN systematic error.
2. Variation of statistical summary measures (means, rates, measures of association, etc.) from their true values as a result of systematic variation of measurements, other flaws in data collection, or flaws in study design or analysis.
3. Deviation of inferences from the truth as a result of flaws in study design, data collection, or the analysis or interpretation of results.
4. A tendency of procedures (in study design, data collection, analysis, interpretation, review or publication) to yield results or conclusions which depart from the truth.
5. Prejudice leading to the conscious or unconscious selection of study procedures which depart from the truth in a particular direction, or to one-sidedness in the interpretation of results.
Last, 1988 (#IUPAC)

biased sample: Any sample which is not a random sample.
AN random sample.
BT sample.
RT stratified sample, systematic sample. (#IUPAC)

bilirubin: Orange-yellow pigment (C33H36O6N4), a breakdown product of haem-containing proteins haemoglobin, myoglobin, cytochromes), which circulates in the blood plasma bound to albumin or as water soluble glucuronides, and is excreted in the bile by the liver. (#IUPAC)

bioaccumulation: Progressive increase in the amount of a substance in an organism or part of an organism which occurs because the rate of intake exceeds the organism's ability to remove the substance from the body.
PS bioconcentration, biomagnification. (#IUPAC)

bioaccumulation potential: Ability of living organisms to concentrate a substance obtained either directly from the environment or indirectly through its food.
IPCS, 1978 (#IUPAC)

bioaccumulants: Substances that increase in concentration in living organisms as they take in contaminated air, water, or food because the substances are very slowly metabolized or excreted. (See: biological magnification.) (#CEHN)

bioactivation: Any metabolic conversion of a xenobiotic to a more toxic derivative.
PS activation.
BT biotransformation. (#IUPAC)

bioassay: Procedure for estimating the concentration or biological activity of a substance (vitamin, hormone, plant growth factor, antibiotic etc.) by measuring its effect on an organism compared to an appropriate standard preparation.
Nagel et al. (eds), 1991
BT assay. (#IUPAC)

bioavailability:
1. Extent to which a substance to which the body is exposed (by ingestion, inhalation, injection, or skin contact) reaches the systemic circulation, and the rate at which this occurs.
SN biological availability, physiological availability.
2. Pharmacokinetic term relating systemic exposure from extravascular exposure (ev) to that following intravenous exposure (iv) by the equation:
F = AUCev*Div / AUCiv*Dev
where F is the bioavailability, AUCev and AUCiv are the areas under the plasma concentration time curve following extravascular and intravenous administration and Devand Div are the administered extravascular and intravenous doses. (#IUPAC)

biochemical mechanism: Reaction or series of reactions, usually enzyme-catalysed, associated with a specific physiological event in a living organism. (#IUPAC)

biochemical (biological) oxygen demand (BOD): Substance concentration of oxygen taken up through the respiratory activity of micro-organisms growing on organic compounds present when incubated at a specified temperature (usually 20° C) for a fixed period (usually 5 days). It is regarded as a measure of that organic pollution of water which can be degraded biologically but includes the oxidation of inorganic material such as sulfide and iron(II). The empirical test used in the laboratory to determine BOD also measures the oxygen used to oxidize reduced forms of Nitrogen unless their oxidation is prevented by an inhibitor such as allyl thiourea.
RT [chemical oxygen demand|http://sis.nlm.nih.gov/enviro/glossaryc.html#chemicaloxygendemand].
[Nagel et al. (eds), 1991|http://sis.nlm.nih.gov/enviro/annex3.html#NAGELB (#IUPAC)

biocid/e n., -al adj.: Substance intended to kill living organisms (#IUPAC)

bioconcentration: Process leading to a higher concentration of a substance in an organism than in environmental media to which it is exposed.
PS bioaccumulation, biomagnification.
After WHO, 1979 (#IUPAC)

bioconcentration factor (BCF): Measure of the tendency for a substance in water to accumulate in fish tissue or in issues of other organisms. The equilibrium concentration of a substance in fish can be estimated by multiplying the concentration of the substance in the surrounding water by the fish bioconcentration factor for that chemical. This parameter is an important determinant for human intake by the aquatic food ingestion route.
After USEPA, 1986 (#IUPAC)

bioconversion: See SN biotransformation. (#IUPAC)

biodegradation: Breakdown of a substance catalysed by enzymes in vitro or in vivo. This may be characterized for purposes of hazard assessment as:
1. Primary. Alteration of the chemical structure of a substance resulting in loss of a specific property of that substance.
2. Environmentally acceptable. Biodegradation to such an extent as to remove undesirable properties of the compound. This often corresponds to primary biodegradation but it depends on the circumstances under which the products are discharged into the environment.
3. Ultimate. Complete breakdown of a compound to either fully oxidised or reduced simple molecules (such as carbon dioxide/methane, nitrate/ammonium, and water. It should be noted that the products of biodegradation can be more harmful than the substance degraded.
RT biotransformation.
(International)
bio-elimination: Removal, usually from the aqueous phase, of a test substance in the presence of living organisms by biological processes supplemented by physico-chemical reactions (#IUPAC)

bio-equivalence.: Relationship between two preparations of the same drug in the same dosage form that have a similar bioavailability (#IUPAC)

biologic indicators of exposure study: A study that uses (a) biomedical testing or (b) the measurement of a substance (an analyte), its metabolite, or another marker of exposure in human body fluids or tissues to confirm human exposure to a hazardous substance (also see exposure investigation). (#ATSDR)

*biological absorption(: See absorption, biological. (#IUPAC)

biological acclimatization: See acclimatization, biological. (#IUPAC)

biological assessment of exposure:
1. Assessment of exposure to a substance by the analysis of specimens taken in the environment such as foodstuffs, plants, animals, biological material in air or water samples, or biological material from exposed subjects. When human samples are analysed, they are usually urine and blood; other possible samples include expired air, faeces, saliva, bile, hair, and biopsy or autopsy material. When other organisms are being considered, the whole organism may be analysed as well as selected tissues such as fat in pigs or birds. In these samples, the content(s) of the substance(s) or metabolite(s) is determined and, on this basis, the exposure level (concentration in the air, absorbed amount of the substance) or the probability of health impairment due to exposure are derived.
2. Biochemical changes in the components of an organism, such as changes in enzyme activity or in the excretion of metabolic intermediates, can also be used for this purpose if they show a relationship to the exposure.
BT biological monitoring, monitoring. (#IUPAC)

biological cycle: Complete circulatory process through which a substance passes in the biosphere. It may involve transport through the various media (air, water, soil), followed by environmental transformation, and carriage through various ecosystems.
WHO, 1979
RT biosphere,ecosystemhttp://sis.nlm.nih.gov/enviro/glossarye.html#ecosystem]. (#IUPAC)

biological effect monitoring (BEM): Continuous or repeated measurement of early biological effects of exposure to a substance to evaluate ambient exposure and health risk by comparison with appropriate reference values based on knowledge of the probable relationship between ambient exposure and biological effects.
BT biological monitoring,environmental monitoring. (#IUPAC)

biological half-life or half-time (t1/2): Time required for the amount of a substance in a biological system to be reduced to one-half, predominantly by biological processes, when the rate of removal is approximately exponential.
Gold, Loening, McNaught and Sehmi, 1987 (#IUPAC)

biological magnification: The process whereby certain substances such as pesticides or heavy metals move up the food chain by working their way into rivers or lakes and being eaten by aquatic organisms such as fish, which in turn are eaten by large birds, animals or humans. The substances become concentrated in tissues or internal organs as they move up the chain. (See: bioaccumulative.) (#CEHN)

biological monitoring: Continuous or repeated measurement of potentially toxic substances or their metabolites or biochemical effects in tissues, secreta, excreta, expired air or any combination of these in order to evaluate occupational or environmental exposure and health risk by comparison with appropriate reference values based on knowledge of the probable relationship between ambient exposure and resultant adverse health effects.
NT biological effect monitoring
BT environmental monitoring, monitoring.
RT biological assessment of exposure. (#IUPAC)

biological oxygen demand: See SN biochemical oxygen demand. (#IUPAC)

biological preparation: Compound derived from living organisms and their products for use in medicine or as a pesticide etc. SN biological, biopreparation. (#IUPAC)

biological specimen:
1. Organ, tissue (including blood), secretion or excretion product taken from an organism as a sample reflecting the state of the whole organism.
2. Organism taken as a sample reflecting the state of a population or their environment. (#IUPAC)

biological uptake: The transfer of hazardous substances from the environment to plants, animals, and humans. This may be evaluated through environmental measurements, such as measurement of the amount of the substance in an organ known to be susceptible to that substance. More commonly, biological dose measurements are used to determine whether exposure has occurred. The presence of a contaminant, or its metabolite, in human biologic specimens, such as blood, hair, or urine, is used to confirm exposure and can be an independent variable in evaluating the relationship between the exposure and any observed adverse health effects. (#CEHN)

biomarker:
1. Parameter that can be used to identify a toxic effect in an individual organism and can be used in extrapolation between species.
2. Indicator signalling an event or condition in a biological system or sample and giving a measure of exposure, effect, or susceptibility. (#IUPAC)\\\
biomass:
1. Total amount of biotic material, usually expressed per unit surface area or volume, in a medium such as water.
WHO, 1979
2. Material produced by the growth of micro-organisms, plants or animals.
Nagel et al.(eds), 1991 (#IUPAC)

biomedical testing: Testing of persons to find out whether a change in a body function might have occurred because of exposure to a hazardous substance (#ATSDR)

biomineralization: Complete conversion of organic substances to inorganic derivatives by living organisms, especially micro-organisms (#IUPAC)

biomonitoring: See SN biological monitoring (#IUPAC)

biopsy: Excision of a small piece of living tissue for microscopic or biochemical examination; usually performed to establish a diagnosis.
RT autopsy (#IUPAC)

biosphere: Portion of the planet earth which supports and includes life (#IUPAC)

biostatic: Arresting the growth or multiplication of living organisms (#IUPAC)

biota: Plants and animals in an environment. Some of these plants and animals might be sources of food, clothing, or medicines for people (#ATSDR)

biotransformation: Any chemical conversion of substances that is mediated by living organisms or enzyme preparations derived there from.
Nagel et al. (eds), 1991 (#IUPAC)

blood substitution: See SN exchange transfusion (#IUPAC)

B lymphocyte: Type of lymphocyte which synthesizes and secretes antibodies in response to the presence of a foreign substance or one identified by it as foreign. The protective effect can be mediated to a certain extent by the antibody alone (contrast T lymphocyte)
RT immune response, lymphocyte, T lymphocyte (#IUPAC)

Body burden: The total amount of a substance in the body. Some substances build up in the body because they are stored in fat or bone or because they leave the body very slowly (#ATSDR)

bolus:
1. Single dose of a substance, originally a large pill
2. Dose of a substance administered by a single rapid intravenous injection
3. Concentrated mass of food ready to be swallowed
(#IUPAC)

brady-: Prefix meaning slow as in bradycardia or bradypnoea (#IUPAC)

bradycardia: Abnormal slowness of the heartbeat
AN tachycardia (#IUPAC)

bradypnoea: Abnormally slow breathing
AN tachypnoea (#IUPAC)

breathing zone: Space within a radius of 0.5 m from a person's face
IRPTC, 1982 (#IUPAC)

British anti-Lewisite (BAL): See SN 2,3-dimercaptopropan-1-ol (#IUPAC)

bronchoconstriction: Narrowing of the air passages through the bronchi of the lungs
AN bronchodilation (#IUPAC)

bronchodilation: Expansion of the air passages through the bronchi of the lungs
AN bronchoconstriction (#IUPAC)

bronchospasm: Intermittent violent contraction of the air passages of the lungs (#IUPAC)

brownfields: Abandoned, idled, or under-used industrial and commercial facilities where expansion or redevelopment is complicated by real or perceived environmental contamination. (#CEHN)

builder: Material which enhances or maintains the cleaning efficiency of a surfactant, in a detergent, principally by inactivating water hardness; complex phosphates (especially sodium tripolyphosphate, i.e., pentasodium triphosphate), sodium carbonate, and sodium silicate are the builders most commonly used (#IUPAC)

byssinosis: Pneumoconiosis caused by inhalation of dust and associated microbial contaminants and observed in cotton, flax, and hemp workers (#IUPAC)

bystander exposure: Liability of members of the general public to come in contact with substances arising from operations or processes carried out by other individuals in their vicinity (#IUPAC)

C


calcification: Process in which organic tissue becomes hardened by deposition of calcium salts within its substance (#IUPAC)

calibration material: See SN reference material (#IUPAC)

cancer (1): Disease resulting from the development of a malignancy.
RT carcinogen, carcinogenesis,carcinogenic, carcinogenicity,carcinoma, malignant, malignancy (#IUPAC)

cancer (2): Any one of a group of diseases that occur when cells in the body become abnormal and grow or multiply out of control (#ATSDR)
cancer risk: A theoretical risk for getting cancer if exposed to a substance every day for 70 years (a lifetime exposure). The true risk might be lower (#ATSDR)

CAP: see Community Assistance Panel. (#ATSDR)

carboxyhaemoglobin: Compound which is formed between carbon monoxide and haemoglobin in the blood of animals and which is incapable of transporting oxygen (#IUPAC)

Carcinogens n., -ic adj.: Agent (chemical, physical or biological) which is capable of increasing the incidence of malignant neoplasms; the induction of benign neoplasms may in some circumstances contribute to the judgement that an agent is carcinogenic.
IARC,1987 (#IUPAC)

carcinogenesis: Induction, by chemical, physical, or biological agents, of malignant neoplasms.
WHO,1989a (#IUPAC)

carcinogenicity, classification according to IARC: Classification based on the weight of the evidence and not on potency as follows.
1. Sufficient evidence. Causal relationship has been established between exposure to the agent and human cancer: a positive relationship has been observed between exposure to the agent and cancer in studies in which chance, bias and confounding could be ruled out with reasonable confidence.
2. Limited evidence. Positive association has been observed between exposure to the agent and cancer for which a causal interpretation is considered to be credible, but chance, bias or confounding could not be ruled out with reasonable confidence.
3. Inadequate evidence. Available studies are of insufficient quality, consistency or statistical power to permit a conclusion regarding the presence or absence of a causal association.
4. Evidence suggesting lack of carcinogenicity. There are several adequate studies covering the full range of doses to which human beings are known to be exposed, which are mutually consistent in not showing a positive association between exposure to the agent and any studied cancer at any observed level of exposure. A conclusion of "evidence suggesting lack of carcinogenicity" is inevitably limited to the cancer sites, circumstances and doses of exposure and length of observation covered by the available studies. In addition, the possibility of a very small risk at the levels of exposure studied can never be excluded.
5. Overall evaluation. Total body of evidence is taken into account; the agent is described according to the wording of one of the following categories, and the designated group is given. The categorization of an agent is a matter of scientific judgement, reflecting the strength of the evidence derived from studies in humans and in experimental animals and from other relevant data.

  • Group 1 - The agent is carcinogenic to humans. This category is used only when there is sufficient evidence of carcinogenicity in humans
  • Group 2 - This category includes agents for which, at one extreme, the degree of evidence of carcinogenicity in humans is almost sufficient, as well as agents for which, at the other extreme, there are no human data but for which there is experimental evidence of carcinogenicity. Agents are assigned to either 2A (probably carcinogenic) or 2B (possibly carcinogenic) on the basis of epidemiological, experimental and other relevant data
  • Group 2A - The agent is probably carcinogenic to humans. This category is used when there is limited evidence of carcinogenicity in humans and sufficient evidence of carcinogenicity in experimental animals. Exceptionally, an agent may be classified into this category solely on the basis of limited evidence of carcinogenicity in humans or of sufficient evidence of carcinogenicity in experimental animals strengthened by supporting evidence from other relevant data
  • Group 2B - The agent is possibly carcinogenic to humans.
    This category is generally used for agents for which there is limited evidence in humans in the absence of sufficient evidence in experimental animals. It may also be used when there is inadequate evidence of carcinogenicity in humans or when human data are nonexistent but there is sufficient evidence of carcinogenicity in experimental animals. In some instances, an agent for which there is inadequate evidence or no data in humans but limited evidence of carcinogenicity in experimental animals together with supporting evidence from other relevant data may be placed in this group
  • Group 3 - The agent is not classifiable as to its carcinogenicity to humans. Agents are placed in this category when they do not fall into any other group
  • Group 4 - The agent is probably not carcinogenic to humans. This category is used for agents which there is evidence suggesting lack of carcinogenicity in humans together with evidence suggesting lack of carcinogenicity in experimental animals. In some circumstances, agents for which there is inadequate evidence of or no data on carcinogenicity in humans but evidence suggesting lack of carcinogenicity in experimental animals, consistently and strongly supported by a broad range of other relevant data, may be classified in this group
    IARC,1987 (#IUPAC)

    carcinogenicity test: Long term (chronic) test designed to detect any possible carcinogenic effect of a test substance (#IUPAC)

    carcinoma: Malignant tumour of an epithelial cell.
    SN epithelioma (#IUPAC)

    cardiotoxic: Chemically harmful to the cells of the heart (#IUPAC)

    carry home exposures: Occupational exposures that are transported into the home environment via the clothes, shoes, skin, hair and cars of working parents and consequently become a source of exposure for children. (#CEHN)

    carry-over:
    1. Transfer in farming and agricultural processing of a component from one system such as soil or feed to another system such as a plant, animal or human being: carry-over is expressed as the concentration of a component in the second system divided by the concentration in the first.
    2. Process in analytical studies by which materials are carried into a reaction mixture in which they do not belong. (#IUPAC)

    CAS registry number: A unique number assigned to a substance or mixture by the American Chemical Society Abstracts Service (#ATSDR)
    case control study: A study which starts with the identification of persons with the disease (or other outcome variable) of interest, and a suitable control (comparison, reference) group of persons without the disease. The relationship of an attribute to the disease is examined by comparing the diseased and non-diseased with regard to how frequently the attribute is present or, if quantitative, the levels of the attribute, in the two groups (#IUPAC)

    SN case comparison study, case history study, case referent study, retrospective study.
    Last, 1988 (#IUPAC)

    catabolism:
    1. Reactions involving the oxidation of organic substrates to provide chemically available energy (for example ATP) and to generate metabolic intermediates.
    Nagel et al.(eds), 1990
    2. Generally, process of breakdown of complex molecules into simpler ones, often providing biologically available energy.
    AN anabolism (#IUPAC)

    catatonia: Schizophrenia marked by excessive, and sometimes violent, motor activity and excitement, or by generalised inhibition (#IUPAC)

    cathartic: See SN laxative. SN purgative (#IUPAC)

    CDC: See "Centers for Disease Control." (#Glossary)

    ceiling value (CV): U.S. term in occupational exposure indicating the airborne concentration of a potentially toxic substance which should never be exceeded in a worker's breathing zone (#IUPAC)

    cell line: Defined unique population of cells obtained by culture from a primary implant through numerous generations (#IUPAC)

    cell-mediated hypersensitivity: State in which an individual reacts with allergic effects caused by the reaction of antigen-specific T-lymphocytes following exposure to a certain substance (allergen) after having been exposed previously to the same substance or chemical group.
    RT allergy, antigen, immunoglobulin E-mediated hypersensitivity (#IUPAC)

    cell-mediated immunity: Immune response mediated by antigen-specific T-lymphocytes (#IUPAC)

    cell strain: Cells having specific properties or markers derived from a primary culture or cell line (#IUPAC)

    censored data: Sample observations for which the complete distribution is not known: for example, a cohort study in which some persons cannot be followed to the predetermined end of the study ("right-censored data") or environmental assay data in which some results are less than the sample detection limit ("left-censored data").
    After Last, 1988 (#IUPAC)

    Centers for Disease Control and Prevention (CDC or CDCP): The CDC, part of the U.S. Department of Health and Human Services, provides federal leadership in the prevention and control of diseases. The CDC includes many programs that conduct research and provide information on public health issues such as occupational health, AIDS, cancer, infectious diseases and other diseases (#Glossary)

    central nervous system: The part of the nervous system that consists of the brain and the spinal cord (#ATSDR)

    CERCLA: see Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (#ATSDR)

    certified reference material: Reference material provided by a certifying body such as a National Standards Organization or Metrological Laboratory or by an international body which confirms its purity and analytical values by technically valid procedures and provides a certificate detailing the relevant information.
    BT reference material (#IUPAC)

    chain of custody: Sequence of responsibility for a substance from the manufacturer to the distributor, to the user, or to the person(s) ultimately responsible for waste disposal. This term is also used in controlled transmission of samples from collection to analysis, especially of samples of materials used for medico-legal or forensic purposes (#IUPAC)

    chelation therapy: Treatment with a chelating agent to enhance the elimination or reduce the toxicity of a metal ion (#IUPAC)

    chemical aetiologic agent: See SN toxic substance (#IUPAC)

    chemical conversion: Change from one state or chemical structure to another.
    PS conversion (#IUPAC)

    chemical oxygen demand (COD): Substance concentration of available oxygen (derived from a chemical oxidizing agent) required to oxidize the organic (and inorganic) matter in waste water.
    After Nagel et al. (eds), 1991
    RT [biochemical oxygen demand|http://sis.nlm.nih.gov/enviro/glossaryb.html#biochemicalbiologicaloxygendemand] (#IUPAC)

    chemical safety: Practical certainty that there will be no exposure of organisms to toxic amounts of any substance or group of substances: this implies attaining an acceptably low risk of exposure to potentially toxic substances.
    Duffus, 1986
    RT practical certainty (#IUPAC)

    chemical species: Set of chemically identical atomic or molecular structural units in a solid array or of chemically identical molecular entities that can explore the same set of molecular energy levels on the time scale of the experiment (#IUPAC)
  • For example, two conformational isomers may interconvert sufficiently slowly to be detectable by separate nuclear magnetic resonance spectra and hence be considered to be separate chemical species on a time scale governed by the radiofrequency of the spectrometer used. On the other hand, in a slow chemical reaction the same mixture of conformers may behave as a single chemical species, i.e., there is a virtually complete equilibrium population of the total set of molecular energy levels belonging to the two conformers. Except where the context requires otherwise, the term is taken to refer to a set of molecular entities containing isotopes in their natural abundance. (#IUPAC)

    The wording of the definition given is intended to embrace both cases such as graphite, sodium chloride, or a surface oxide where the basic structural units are not capable of a separate existence as well as those cases where they are.
    Gold, Loening, McNaught and Sehmi, 1987 (#IUPAC)

    chemical toxicology: See BT toxicology (#IUPAC)

    chemobiokinetics: See NT toxicokinetics (#IUPAC)

    chemophobia: Irrational fear of chemicals (#IUPAC)

    chemosis: Chemically induced swelling around the eye caused by oedema of the conjunctiva (#IUPAC)

    chemosterilizer: Substance used to sterilize mites, insects, rodents or other animals (#IUPAC)

    chloracne: Acne-like eruption caused by exposure to certain chlorinated organic substances such as polychlorinated biphenyls or 2,3,7,8-tetrachlorodibenzo-p-dioxin (#IUPAC)

    cholinomimetic: See SN parasympathomimetic (#IUPAC)

    cholinesterase inhibitor: Substance which inhibits the action of acetylcholinesterase (EC 3.1.1.7) and related enzymes which catalyse the hydrolysis of choline esters: such a substance causes hyperactivity in parasympathetic nerves (#IUPAC)

    chromatid: Either of two filaments joined at the centromere which make up a chromosome (#IUPAC)

    chromatin: Stainable complex of DNA and proteins present in the nucleus of a eukaryotic cell.
    RT eukaryote (#IUPAC)

    chromosomal aberration: Abnormality of chromosome number or structure(#IUPAC)

    chromosome: Self-replicating structure consisting of DNA complexed with various proteins and involved in the storage and transmission of genetic information; the physical structure that contains the genes.
    Nagel et al. (eds), 1991
    RT chromatid (#IUPAC)

    *chronic *: Occurring over a long time (compare with acute). (#ATSDR)

    chronic effect: Consequence which develops slowly and has a long-lasting course (often but not always irreversible).
    After WHO, 1979
    AN acute effect (#IUPAC)

    chronic exposure: Continued exposures occurring over an extended period of time, or a significant fraction of the test species' or of the group of individuals', or of the population's life-time.
    AN acute exposure. chronic toxicity:
    1. Adverse effects following chronic exposure.
    2. Effects which persist over a long period of time whether or not they occur immediately upon exposure or are delayed.
    IRIS, 1986
    AN acute toxicity (#IUPAC)

    chronic toxicity test: Study in which organisms are observed during the greater part of the life span and in which exposure to the test agent takes place over the whole observation time or a substantial part thereof.
    WHO, 1978a
    AN acute toxicity test.
    SN long term test (#IUPAC)

    chronotoxicology: Study of the influence of biological rhythms on the toxicity of substances (#IUPAC)

    circulation of substances in the environment: Movement of xenobiotic substances in the environment with air flow, river current, soil, water, etc.
    RT biological cycle.
    IRPTC, 1982 (#IUPAC)

    Cirrhosis:
    1. Liver disease defined by histological examination and characterized by increased fibrous tissue, abnormal physiological changes such as loss of functional liver cells, and increased resistance to blood flow through the liver portal hypertension).
    2. Interstitial fibrosis of an organ.
    (#IUPAC)

    clastogen: Agent causing chromosome breakage and/or consequent gain, loss or rearrangement of pieces of chromosomes (#IUPAC)

    clastogenesis: Occurrence of chromosomal breaks and/or consequent gain, loss or rearrangement of pieces of chromosomes (#IUPAC)

    clearance:
    1. Volume of blood or plasma or mass of an organ effectively cleared of a substance by elimination (metabolism and excretion) in a given time interval: clearance is expressed in units of volume or mass per unit of time. Total clearance for a component is the sum of the clearances of each eliminating organ or tissue for that component.
    2. In pulmonary toxicology, clearance refers specifically to removal of any inhaled substance which deposits on the lining surface of the lung: lung clearance is expressed in volume or mass of lung cleared per unit time.
    3. In renal toxicology, clearance refers to the quantification of the removal of a substance by the kidneys by the processes of filtration and secretion: clearance is calculated by relating the rate of renal excretion to the plasma concentration.
    RT elimination (#IUPAC)

    *clone.:
    1. Population of genetically identical cells or organisms having a common ancestor.
    2. To produce such a population.
    3. Recombinant DNA molecules all carrying the same inserted sequence.
    Nagel et al. (eds), 1991

    clonic: Pertaining to alternate muscular contraction and relaxation in rapid succession.
    RT tonic.
    IRIS, 1986 (#IUPAC)

    cluster investigation: A review of an unusual number, real or perceived, of health events (for example, reports of cancer) grouped together in time and location. Cluster investigations are designed to confirm case reports; determine whether they represent an unusual disease occurrence; and, if possible, explore possible causes and contributing environmental factors (#ATSDR)
    cluster sampling:
    1. A method of sampling in which the population is divided into aggregates (or clusters) of items bound together in a certain manner. A sample of these clusters is taken at random and all the items which constitute them are included in the sample.
    2. A sampling method in which each unit selected is a group of persons (all persons in a city block, a family, etc.) rather than an individual.
    WHO,1989a
    (#IUPAC)

    cocarcinogen: Chemical, physical or biological factor which intensifies the effect of a carcinogen (#IUPAC)

    codex alimentarius: Collection of internationally adopted food standards drawn up by the Codex Alimentarius Commission, the principal body implementing the joint FAO/WHO Food Standards Programme.
    IPCS, 1978 (#IUPAC)

    cohort: Component of the population born during a particular period and identified by period of birth so that its characteristics (such as causes of death and numbers still living) can be ascertained as it enters successive time and age periods. The term "cohort" has broadened to describe any designated group of persons followed or traced over a period of time, as in the term cohort study (prospective study).
    Last, 1988 (#IUPAC)

    cohort analysis: Tabulation and analysis of morbidity or mortality rates in relationship to the ages of a specific group of people (cohort), identified by their birth period, and followed as they pass through different ages during part or all of their life span. In certain circumstances such as studies of migrant populations, cohort analysis may be performed according to duration of residence in a country rather than year of birth, in order to relate health or mortality experience to duration of exposure. Last, 1988 (#IUPAC)

    cohort study: Method of epidemiological study in which subsets of a defined population can be identified who are, have been, or in the future may be exposed or not exposed, or exposed in different degrees, to a factor or factors hypothesized to influence the probability of occurrence of a given disease or other outcome. Alternative terms for such a study - follow-up, longitudinal, and prospective study - describe an essential feature of the method, observation of the population for a sufficient number of person-years to generate reliable incidence or mortality rates in the population subsets. This generally means studying a large population, study for a prolonged period (years), or both.
    SN concurrent study, follow-up study, incidence study, longitudinal study, prospective study.
    Last, 1988 (#IUPAC)

    combined effect of poisons: Simultaneous or successive effect of two or more poisons on the organism by the same route of exposure.
    RT additive effect,antagonism, independent effects of poisons, potentiation, summation, synergism.
    IRPTC,1982 (#IUPAC)

    cometabolism: Process by which a normally non-biodegradable substance is biodegraded only in the presence of an additional carbon source.
    RT analogue metabolism. (#IUPAC)

    Community Assistance Panel (CAP):
    A group of people from a community and from health and environmental agencies who work with ATSDR to resolve issues and problems related to hazardous substances in the community. CAP members work with ATSDR to gather and review community health concerns, provide information on how people might have been or might now be exposed to hazardous substances, and inform ATSDRon ways to involve the community in its activities (#ATSDR)

    comparison group: See SN control group (#IUPAC)

    community health investigation:
    Medical or epidemiologic evaluation of descriptive health information about individual persons or a population of persons to evaluate and determine health concerns and to assess the likelihood that they may be linked to exposure to hazardous substances. (#CEHN)

    community Right-to-Know reporting requirements: Part of the Emergency Planning and Community Right-to-Know Act of 1986 (EPCRA), the Community Right-to-Know Reporting Requirements (Sections 311-312) establish reporting requirements which provide the public with important information on the hazardous chemicals in their communities. The purpose is to increase community awareness of chemical hazards and to facilitate emergency planning. (#CEHN)

    comparison value (CV): Calculated concentration of a substance in air, water, food, or soil that is unlikely to cause harmful (adverse) health effects in exposed people. The CV is used as a screening level during the public health assessment process. Substances found in amounts greater than their CVs might be selected for further evaluation in the public health assessment process. (#ATSDR)

    compartment: Part of the body considered as an independent system for purposes of assessment of distribution and clearance of a substance. The body is composed of a large number of organs, tissues, cells, cell organelles and fluids, any one of which could be referred to as a compartment. In kinetic considerations, a compartment often refers collectively to the organs, tissues, cells, and fluids for which the rates of uptake and subsequent distribution and elimination are sufficiently similar to preclude kinetic resolution.
    WHO, 1979 (#IUPAC)

    compensation: Adaptation of an organism to changing conditions of the environment (especially chemical) is accompanied by the emergence of stresses in biochemical systems which exceed the limits of normal (homeostatic) mechanisms. Compensation is a temporary concealed pathology which later on can be manifested in the form of explicit pathological changes (decompensation).
    SN pseudoadaptation.
    RT acclimatization, adaptation. (#IUPAC)

    competent authority: In the context of European Communities Directive 79/831/EEC, the Sixth Amendment to the European Community's Directive 67/548/EEC relating to the Classification, Packaging and Labelling of Dangerous Substances, official government organization or group receiving and evaluating notifications of new substances. (#IUPAC)

    competent bacteria: Culture of bacteria (or yeast) treated in such a way that their ability to take up DNA molecules without transduction or conjugation has been enhanced (#IUPAC)

    completed exposure pathway: see exposure pathway. (ATSDR)
    complete mineralization: Complete breakdown of a complex organic compound to carbon dioxide, water, oxides and oxidative inorganic products such as nitrate or sulfate (#IUPAC)

    composite sample: A sample which is made by combining samples from two or more locations. The sample can be of water, soil or another medium (Glossary)
    comprehensive effect of poisons: Simultaneous or successive effect made on an organism by poisons entering from different media, from air, from water, from food or through the skin (#IUPAC)\\\
    Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980 (CERCLA)
    CERCLA, also known as Superfund, is the federal law that concerns the removal or cleanup of hazardous substances in the environment and at hazardous waste sites. ATSDR, which was created by CERCLA, is responsible for assessing health issues and supporting public health activities related to hazardous waste sites or other environmental releases of hazardous substances. This law was later amended by the Superfund Amendments and Reauthorization Act (SARA). (#ATSDR)
    concentration (amount-of-substance concentration) c = n/v: Derived kind-of-quantity defined as the amount of substance (thumbs down) of a component specified by an elementary entity divided by the volume (V) of the system containing the component. The fundamental unit is mol m-3 but practical units are mol dm-3 or mol L-1 (not molarity).
    After Gold, Loening, McNaught and Sehmi, 1987
    RT absolute lethal concentration, lethal concentration, maximum tolerable concentration, median effective concentration, median lethal concentration, median narcotic concentration, minimum lethal concentration, threshold concentration. (#IUPAC)

    concentration-effect curve: Graph of the relation between exposure concentration and the magnitude of the resultant biological change.
    RT dose-effect curve.
    SN exposure effect curve (#IUPAC)

    concentration-effect relationship: Association between exposure concentration and the magnitude of the resultant continuously graded change, either in an individual or in a population.
    RT dose-effect relationship (#IUPAC)

    concentration-response curve: Graph of the relation between exposure concentration and the proportion of individuals in a population responding with a quantal effect.
    RT dose-response curve, response ((#IUPAC)

    concentration-response relationship: Association between exposure concentration and the incidence of a defined biological effect in an exposed population.
    RT dose-response relationship, response (#IUPAC)

    *concordance.: Pairs or groups of individuals of identical phenotype: in twin studies, a condition in which both twins exhibit or fail to exhibit a trait under investigation.
    Last, 1988
    RT phenotype (#IUPAC)

    concurrent study: See SN cohort study (#IUPAC)

    concurrent validity: Measurement and its criterion refer to the same point in time: an example would be a visual inspection of a wound for evidence of infection validated against bacteriological examination of a specimen taken at the same time.
    Last, 1988 (#IUPAC)

    confounding:
    1. Situation in which the effects of two processes are not distinguishable from one another: the distortion of the apparent effect of an exposure on risk brought about by the association of other factors which can influence the outcome.
    2. Relationship between the effects of two or more causal factors as observed in a set of data, such that it is not logically possible to separate the contribution which any single causal factor has made to an effect.
    3. Situation in which a measure of the effect of an exposure on risk is distorted because of the association of exposure with other factor(s) which influence the outcome under study.
    Last, 1988 (#IUPAC)

    confounding variable: Changing factor that can cause or prevent the outcome of interest, is not an intermediate variable, and is not associated with the factor under investigation: such a variable must be controlled in order to obtain an undistorted estimate of the effect of the study factor on risk.
    SN confounder.
    Last, 1988 (#IUPAC)

    congener: Substance which by structure, function or origin is similar to another (#IUPAC)

    conjugate:
    1. Derivative of a substance formed by its combination with compounds such as acetic acid, glucuronic acid, glutathione, glycine, sulfuric acid etc.
    RT phase 2 reaction.
    2. Material produced by attaching two or more substances together, for example - conjugates of antibody with fluorochromes, radio-isotopes or enzymes.
    (International)
    conjunctiva: Mucous membrane which covers the eyeball and lines the under-surface of the eyelid (#IUPAC)

    conjunctivitis: Inflammation of the conjunctiva (#IUPAC)

    conservative assessment of risk: Assessment of risk which assumes the worst possible case scenario and therefore gives the highest possible value for risk: risk management decisions based on this value will maximize safety (#IUPAC)

    construct validity: Extent to which the measurement corresponds to theoretical concepts (constructs) concerning the phenomenon under study; for example, if on theoretical grounds, the phenomenon should change with age, a measurement with construct validity would reflect such a change.
    Last, 1988 (#IUPAC)

    Consumer Product Safety Commission (CPSC): The CPSC, a federal commission, protects the public from injury caused by consumer products. The CPSC evaluates products, investigates the causes of product-related injuries and issues and enforces safety standards. For example, the CPSC has banned certain products containing asbestos. The CPSC also regulates the lead content of paints. (#Glossary)

    contact dermatitis: Inflammatory condition of the skin resulting from dermal exposure to an allergen (sensitizer) or an irritating (corrosive, defatting) substance (#IUPAC)

    containment: Process by which possible release, discharge or spill of a toxic substance during normal use or after an accident is prevented by appropriate action (#IUPAC)

    contaminant:
    1. Minor impurity present in a substance.
    2. Extraneous material inadvertently added to a sample prior to or during chemical or biological analysis.
    3. In some contexts, as in relation to gas cleaning equipment, used as a synonym for "pollutant", especially on a small scale.
    4. Unintended component in food that may pose a hazard to the consumer. PS pollutant.
    (#IUPAC)

    content validity: Extent to which the measurement incorporates the domain of the phenomenon under study; for example, a measurement of functional health status should embrace activities of daily living, occupational, family, and social functioning, etc.
    Last, 1988 (#IUPAC)

    contraindication: Any condition which renders some particular line of treatment improper or undesirable (#IUPAC)

    control group: Selected group, identified as a rule before a study is done, which comprises humans, animals, or other species who do not have the disease, intervention, procedure or whatever is being studied, but in all other respects is as nearly identical to the test group as possible.
    After Last, 1988
    SN comparison group (#IUPAC)

    control, matched: Control (individual or group or case) selected to be similar to a study individual or group, or case, in specific characteristics: some commonly used matching variables are age, sex, race and socio-economic status.
    After WHO, 1989a (#IUPAC)

    conversion: See NT chemical conversion, biotransformation (#IUPAC)

    core grade: Quality rating, based on standard evaluation criteria established by the US Office of Pesticide Programs regulatory agencies, given to toxicological studies after submission by registrants.
    IRIS, 1986 (#IUPAC)

    corrosive: Causing a surface-destructive effect on contact; in toxicology, this normally means causing visible destruction of the skin, eyes, or the lining of the respiratory tract or the gastrointestinal tract (#IUPAC)

    count mean diameter: Mean of the diameters of all particles in a population.
    WHO, 1989a (#IUPAC)

    count median diameter: Calculated diameter in a population of particles in a gas or liquid phase above which there are as many particles with larger diameters as there are particles below it with smaller diameters.
    WHO, 1989a (#IUPAC)

    CPSC: See "Consumer Product Safety Commission" (#Glossary)

    crackles: See SN crepitations (#IUPAC)

    crepitations: Abnormal respiratory sounds heard on auscultation of the chest, produced by passage of air through passages which contain secretion or exudate or which are constricted by spasm or a thickening of their walls; more usually referred to as crepitations or rhonchi (auscultation is the process of listening for sounds within the body by ear unassisted or using a stethoscope).
    SN crackles, râles (#IUPAC)

    criterion: Validated set of data used as a basis for judgement.
    WHO, 1989a (#IUPAC)

    criterion validity: Extent to which the measurement correlates with an external criterion of the phenomenon under study.
    Last, 1988 (#IUPAC)

    critical concentration (for a cell or organ): Concentration of a potentially toxic substance at which undesirable (or adverse) functional changes, reversible or irreversible, occur in the cell or organ (#IUPAC)

    critical effect: For deterministic effects, the first adverse effect which appears when the threshold (critical) concentration or dose is reached in the critical organ. Adverse effects, such as cancer, with no defined threshold concentration are often regarded as critical. Decision on whether an effect is critical is a matter of expert judgment.
    After WHO, 1989a (#IUPAC)

    critical end-point: Toxic effect used by the USEPA as the basis for a reference dose.
    RT //sis.nlm.nih.gov/enviro/glossaryr.html.
    Barnes and Dourson, 1988 (#IUPAC)

    critical group: Part of a target population most in need of protection because it is most susceptible to a given toxicant.
    WHO,1979 (#IUPAC)

    critical organ:
    1. In toxicology. Organ which first attains the critical concentration (of a potentially toxic substance) under specified circumstances of exposure and for a given population.
    2. In radiation biology. Organ the damage of which (by radiation) results in the greatest injury to the individual (or his/her descendants). The injury may result from inherent radiosensitivity or indispensability of the organ, or from high dose, or from a combination of all three.
    ICRP, 1965
    (International)
    critical organ concentration (of a substance): Mean concentration in the critical organ at the time the most sensitive type of cell reaches the critical concentration.
    RT critical concentration, critical organ (#IUPAC)

    critical period (of development): Stage of development of an organism that is of particular importance in the life cycle if the normal full development of some anatomical, physiological, metabolic, or psychological structure or function is to be attained: such a period may be associated with very high susceptibility to specific potentially toxic substances (#IUPAC)

    critical study: Investigation yielding the no-observed adverse effect level that is used by the EPA as the basis of the reference dose.
    Barnes and Dourson, 1988
    RT reference dose (#IUPAC)

    cross-product ratio: See SN odds ratio (#IUPAC)

    cross-sectional study (of disease prevalence and associations): Study which examines the relationship between diseases (or other health-related characteristics) and other variables of interest as they exist in a defined population at one particular time. Disease prevalence rather than incidence is normally recorded in a cross-sectional study and the temporal sequence of cause and effect cannot necessarily be determined
    SN disease frequency survey, prevalence study
    RT morbidity survey
    After Last, 1988 (#IUPAC)

    *cumulative effect8: Overall adverse change which occurs when repeated doses of a harmful substance or radiation have biological consequences which are mutually enhancing.
    SN functional accumulation (#IUPAC)

    cumulative exposure: The summation of exposures of an organism to a chemical over a period of time. (#CEHN)

    cumulative incidence, cumulative incidence rate: Number and proportion of a group of people who experience the onset of a health-related event during a specified time interval; this interval is generally for all members of the group, but, as in lifetime incidence, it may vary from person to person without reference to age
    Last, 1988 (#IUPAC)

    cumulative incidence ratio: Value obtained by dividing the cumulative incidence rate in the exposed population by the cumulative incidence rate in the unexposed population
    Last,1988 (#IUPAC)

    cumulative median lethal dose: Estimate of the total administered amount of a substance which is associated with the death of half a population of animals when the substance is administered repeatedly in doses which are generally fractions of the median lethal dose. The estimate may vary with the chosen size of the fraction (0.1, 0.2 etc.) and with the period of time over which effects are observed. It is a calculated quantity generally obtained by interpolation of available dose-response data relating the total administered amount to the response in the corresponding group of experimental animals
    BT[ median lethal dose|http://sis.nlm.nih.gov/enviro/glossarym.html#medianlethaldose] (#IUPAC)

    cutaneous: Pertaining to the skin
    SN dermal (#IUPAC)

    cyanogenic: Compounds able to produce Cyanide; examples are the cyanogenic glycosides such as amygdalin in peach and apricot stones (#IUPAC)

    cyanosis: Bluish coloration, especially of the skin and mucous membranes and fingernail beds, caused by abnormally large amounts of reduced haemoglobin in the blood vessels as a result of deficient oxygenation (#IUPAC)

    cytochrome: Haemoprotein whose characteristic mode of action involves transfer of reducing equivalents associated with a reversible change in oxidation state of the haem prosthetic group: strictly, the cytochrome P450 family are not cytochromes but haem-thiolate proteins.
    Palmer and Reedijk, 1991 (#IUPAC)

    cytochrome P-420: Inactive derivative of cytochrome P-450 found in microsomal preparations.
    RT cytochrome P-448, cytochrome P-450, endoplasmic reticulum, microsome, mono-oxygenase, phase 1 reactions (#IUPAC)

    cytochrome P-450: Haemoproteins which form the major part of the enzymes concerned with the mono-oxygenation of many endogenous and exogenous substrates. The term includes a large number of iso-enzymes which are coded for by a superfamily of genes. Endogenous substrates of these enzymes include cholesterol, steroid hormones and the eicosenoids; the exogenous substrates are xenobiotics. Strictly, the cytochrome P450 family are not cytochromes but are haem-thiolate proteins.
    SN mixed-function oxidase.
    RT cytochrome P-420, cytochrome P-448, endoplasmic reticulum, microsome, mono-oxygenase, phase 1 reactions, xenobiotics.
    Guengerich, 1988 (#IUPAC)

    cytogenetics: Branch of genetics which correlates the structure and number of chromosomes as seen in isolated cells with variation in genotype and phenotype.
    RT phenotype (#IUPAC)

    cytoplasm: Fundamental substance or matrix of the cell (within the plasma membrane) which surrounds the nucleus, endoplasmic reticulum, mitochondria and other organelles (#IUPAC)

    cytotoxic: Causing damage to cell structure or function (#IUPAC)

D


death rate: Estimate of the proportion of a population which dies during a specified period. The numerator is the number of persons dying during the period; the denominator is the size of the population, usually estimated as the mid-year population. The death rate in a population is generally calculated by the formula:
10n (Number of deaths during a specified period) / (Number of persons at risk of dying during the period)
This rate is an estimate of the person-time death rate, the death rate per 10n person-years: usually n = 3. If the rate is low, it is also a good estimate of the cumulative death rate. This rate is also called the crude death rate
Last, 1988
PS mortality, mortality rate (#IUPAC)

DEC: See "New York State Department of Environmental Conservation." (#Glossary)

decompensation: Explicit pathophysiological changes following compensation for adverse effects (#IUPAC)

decontamination: Process of rendering harmless (by neutralization, elimination, removal etc.) a potentially toxic substance in the natural environment, laboratory areas, the workplace, other indoor areas, clothes, food, water, sewage etc (#IUPAC)

defoliant: Substance used for removal of leaves by its toxic action on living plants (#IUPAC)

dehydrogenase: Enzyme which catalyses oxidation of compounds by removing hydrogen (#IUPAC)

delayed effect: Consequence occurring after a latent period following the end of exposure to a toxic substance or other harmful environmental factor (International)
SN latent effect
denaturation:
1. Addition of methanol or acetone to alcohol to make it unfit for drinking
2. Change in molecular structure of proteins so that they cannot function normally, often caused by splitting of hydrogen bonds following exposure to reactive substances or heat
(International)
denitrification: Reduction of nitrates to nitrites, nitrous oxides or dinitrogen (N2) catalysed by facultative aerobic soil bacteria under anaerobic conditions
Nagel et al. (eds),1990 (#IUPAC)

dental fluorosis: Variety of tooth enamel malformations due to excessive fluoride exposure during dental development (#IUPAC)

deoxyribonucleic acid (DNA): Constituent of chromosomes which stores the hereditary information of an organism in the form of a sequence of purine and pyrimidine bases: this information relates to the synthesis of proteins and hence it is a determinant of all physical and functional activities of the cell, and consequently of the whole organism
RT ribonucleic acid (RNA) (#IUPAC)

dependence:
1. A psychic craving for a drug or other substance which may or may not be accompanied by a physical dependency
2. Reliance on a drug or other substance to maintain health
PS addiction
(International)
depilatory: Substance causing loss of hair (#IUPAC)

deposition:
1. Process by which a substance arrives at a particular organ or tissue site, for example the deposition of particles on the ciliated epithelium of the bronchial airways.
2. Process by which a substance sediments out of the atmosphere or water and settles in a certain place
PS accumulation
(#IUPAC)

dermal: Pertaining to the skin
SN cutaneous (#IUPAC)

dermal contact: Contact with (touching) the skin (see route of exposure). (#ATSDR)

dermal irritation: Skin reaction resulting from a single or multiple exposure to a physical or chemical entity at the same site, characterised by the presence of inflammation; it may result in cell death (#IUPAC)

dermatitis: Inflammation of the skin: contact dermatitis is due to local exposure and may be caused by irritation, allergy or infection (#IUPAC)

descriptive epidemiology: Study of the occurrence of disease or other health-related characteristics in populations, including general observations concerning the relationship of disease to basic characteristics such as age, sex, race, occupation, and social class; it may also be concerned with geographic location. The major characteristics in descriptive epidemiology can be classified under the headings: individuals, time and place
IPCS, 1978 (#IUPAC)

desensitization: Suppression of sensitivity of an organism to an allergen to which the organism has been exposed previously (#IUPAC)

desiccant:
1. Drying agent
2. In agriculture, a substance used for drying up plants and facilitating their mechanical harvesting.
(International)
desorption: Opposite of adsorption; a decrease in the amount of adsorbed substance
Gold, Loening, McNaught and Sehmi, 1987 (#IUPAC)

desquamation: Shedding of an outer layer of skin in scales or shreds (International)
detection limit: The lowest concentration of a chemical that can reliably be distinguished from a zero concentration (#ATSDR)

detoxification:
1. Process, or processes, of chemical modification which make a toxic molecule less toxic
2. Treatment of patients suffering from poisoning in such a way as to promote physiological processes which reduce the probability or severity of harmful effects
(#IUPAC)

detoxification by haemosorption perfusion: Passage of a patient's blood through a set of columns filled with a haemosorbent (activated charcoal, ion-exchange resin, etc.): the purpose of the operation is to remove a toxic substance from the organism, particularly in an emergency
RT haemoperfusion, haemosorption (#IUPAC)

detriment: Estimated measure of the expected harm or loss associated with an adverse event, usually in a manner chosen to facilitate meaningful addition over different events. It is generally the integrated product of arbitrary values of risk and hazard and is often expressed in terms such as costs in US dollars, loss in expected years of life or loss in productivity, and is needed for numerical exercises such as cost-benefit analysis (#IUPAC)

developmental disorders/effects: Adverse effects such as altered growth, structural abnormality, functional deficiency, or death observed in a developing organism.(1) (#CEHN)

developmental toxicity: Adverse effects on the developing organism (including structural abnormality, altered growth, or functional deficiency or death) resulting from exposure prior to conception (in either parent), during prenatal development, or postnatally up to the time of sexual maturation.
IRIS, 1986
RT embryotoxicity, teratogenicity (#IUPAC)

DHHS: See "U.S. Department of Health and Human Services." (#Glossary)

diaphoresis: Profuse perspiration (#IUPAC)

diaphoretic: Causing profuse perspiration
SN sudorific (#IUPAC)

2,3-dimercaptopropan-1-ol: Metal chelator which has been used in the treatment of arsenic, antimony, gold, mercury and lead poisoning
SN British anti-Lewisite, dimercaprol (#IUPAC)

dimercaprol: See SN 2,3-dimercaptopropan-1-ol

diploid: Chromosome state in which the chromosomes are present in homologous pairs. Normal human somatic (non-reproductive) cells are diploid (they have 46 chromosomes), whereas reproductive cells, with 23 chromosomes, are haploid
RT haploid, meiosis, mitosis (#IUPAC)

discharge: See SN emission (#IUPAC)

discharge (effluent, emission) standard or release limit: Maximum amount of a pollutant released from a given source to a specified medium which is acceptable under specified circumstances
WHO, 1979 (#IUPAC)

discordance (genetic): Any difference in a character between individuals due to genetic differences such as may occur in dizygotic twins, or between matched pairs in a case cohort study
AN concordance (#IUPAC)

disease: Literally, dis-ease, lack of ease; pathological condition that presents a group of symptoms peculiar to it and which establishes the condition as an abnormal entity different from other normal or pathological body states

discontinuous effect: See SN intermittent effect (International)
disease prevention: Measures used to prevent a disease or reduce its severity (#ATSDR)

disease registry: A system of ongoing registration of all cases of a particular disease or health condition in a defined population (ATSDR)
disposition: Natural tendency shown by an individual or group of individuals, including any tendency to acquisition of specific diseases, often due to hereditary factors (#IUPAC)

dissipation: Reduction in the amount of a Pesticide or other compound which has been applied to plants, soil etc. (used when it is not clear whether this is by mineralization degradation, binding, or leaching) (#IUPAC)

distributed source: See SN area source
RT point source (#IUPAC)

distribution:
1. Dispersal of a substance and its derivatives throughout the natural environment.
2. Dispersal of a substance within an organism, including metabolism, storage and excretion.
3. Final location of a substance within an organism after dispersal.
(#IUPAC)

diuresis: Excretion of urine, especially in excess (#IUPAC)

diuretic: Agent which increases urine production
SN micturitic (International)
DOD : United States Department of Defense (#ATSDR)

DOE: United States Department of Energy (#ATSDR)

dosage: Dose expressed as a function of the organism being dosed and time, for example mg/(kg body weight)/day
See dose (#IUPAC)

dose: Total amount of a substance administered to, taken or absorbed by an organism
NT absolute lethal dose,

  • cumulative median lethal dose,
  • lethal dose,
  • maximum tolerable dose,
  • median effective dose,
  • median lethal dose,
  • median narcotic dose,
  • minimum lethal dose,
  • non-effective dose,
  • organ dose,
  • threshold dose,
  • toxic dose (#IUPAC)

    dose (for chemicals that are not radioactive): The amount of a substance to which a person is exposed over some time period. Dose is a measurement of exposure. Dose is often expressed as milligram (amount) per kilogram (a measure of body weight) per day (a measure of time) when people eat or drink contaminated water, food, or soil. In general, the greater the dose, the greater the likelihood of an effect. An "exposure dose" is how much of a substance is encountered in the environment. An "absorbed dose" is the amount of a substance that actually got into the body through the eyes, skin, stomach, intestines, or lungs. (#ATSDR)

    dose (for radioactive chemicals): The radiation dose is the amount of energy from radiation that is actually absorbed by the body. This is not the same as measurements of the amount of radiation in the environment. (#ATSDR)

    dose-effect curve: Graph of the relation between dose and the magnitude of the biological change produced measured in appropriate units
    RT concentration-effect curve (#IUPAC)

    dose-effect relationship: Association between dose and the magnitude of a continuously graded effect, either in an individual or in a population or in experimental animals
    RT concentration-effect relationship (#IUPAC)

    dose-related effect: Situation in which the magnitude of a biological change is related to the dose
    AN non-dose-related effect (#IUPAC)

    dose-response curve: Graph of the relation between dose and the proportion of individuals in a population responding with an all-or-none effect
    RT concentration-response curve, response (#IUPAC)

    dose-response relationship: Association between dose and the incidence of a defined biological effect in an exposed population
    RT concentration-response relationship, response (#IUPAC)

    draize test: Evaluation of materials for their potential to cause dermal or ocular irritation and corrosion following local exposure; generally using the rabbit model (almost exclusively the New Zealand White) although other animal species have been used (#IUPAC)

    drug: Any substance which when absorbed into a living organism may modify one or more of its functions. The term is generally accepted for a substance taken for a therapeutic purpose, but is also commonly used for abused substances
    SN medicine, pharmaceutical
    After WHO, 1978a (#IUPAC)

    duplicate portion sampling method (diet/food): Method frequently used for the same purposes as the total diet study technique. Test persons consume their ordinary diet but for each meal, they prepare for subsequent analysis a duplicate portion of all food as prepared, served and consumed
    SN duplicate diet study (#IUPAC)

    duplicate (replicate) samples (in chemistry): Two (or multiple) samples taken under the same or comparable conditions
    PAC, 1990 (#IUPAC)

    dysarthria: Imperfect articulation of speech due to neuromuscular damage (#IUPAC)

    dysfunction: Abnormal, impaired, or incomplete functioning of an organism, organ, tissue or cell (#IUPAC)

    [dysplasia[: Abnormal development of an organ or tissue identified by morphological examination (#IUPAC)

    dyspnoea: Difficult or laboured breathing (#IUPAC)

E


ecogenetics: Study of the influence of hereditary factors on the effects of xenobiotics on individual organisms
PS pharmacogenetics, toxicogenetics
RTpolymorphism (#IUPAC)

ecology: Branch of biology which studies the interactions between living organisms and all factors (including other organisms) in their environment: such interactions encompass environmental factors which determine the distributions of living organisms
IPCS, 1978 (#IUPAC)

ecosystem: Grouping of organisms (micro-organisms, plants, animals) interacting together, with and through their physical and chemical environments, to form a functional entity
IPCS, 1978 (#IUPAC)

ecotoxicology: Study of the toxic effects of chemical and physical agents on all living organisms, especially on populations and communities within defined ecosystems; it includes transfer pathways of these agents and their interactions with the environment (#IUPAC)

ectohormone: See SN pheromone (#IUPAC)

ectoparasiticide: Substance intended to kill parasites living on the exterior of the host
IRIS, 1986 (#IUPAC)

eczema: Acute or chronic skin inflammation with erythema, papules, vesicles, pustules, scales, crusts or scabs, alone or in combination, of varied aetiology (#IUPAC)

edema: See SN oedema (#IUPAC)

effective concentration (EC): Concentration of a substance that causes a defined magnitude of response in a given system: EC50 is the median concentration that causes 50 % of maximal response
RT lethal concentration (#IUPAC)

effective dose (ED): Dose of a substance that causes a defined magnitude of response in a given system: ED50 is the median dose that causes 50 % of maximal response
BT dose
RT lethal dose (#IUPAC)

effluent: Fluid, solid or gas discharged from a given source into the external environment
RT emission (#IUPAC)

Electric and Magnetic Fields (EMFs): EMFs consist of low-frequency radiation that is generated when electric current flows through a high-tension wire. EMFs have been associated with an increased incidence of leukemia in children and brain cancer in adults.(6) (#CEHN)

elimination: Expulsion of a substance or other material from an organism (or a defined part thereof), usually by a process of extrusion or exclusion, sometimes after metabolic transformation
RT clearance
WHO, 1979 (#IUPAC)

elimination half-life or half time: Period taken for the plasma concentration of a substance to decrease by half
BT biological half-life or half-time (t1/2) (#IUPAC)

eliminator (of a poison): Substance that contributes to the elimination of a poison from an organism (#IUPAC)

embryo:
1. Stage in the developing mammal at which the characteristic organs and organ systems are being formed: for humans, this involves the stages of development from the second to the eighth week (inclusive post conception)
2. In birds, the stage of development from the fertilization of the ovum up to hatching
3. In plants, the stage of development within the seed
(#IUPAC)

embryotoxicity:
1. Production by a substance of toxic effects in progeny in the first period of pregnancy between conception and the fetal stage
2. Any toxic effect on the conceptus as a result of prenatal exposure during the embryonic stages of development: these effects may include malformations and variations, malfunctions, altered growth, prenatal death, and altered postnatal function
After USEPA, 1989
RT developmental toxicity, teratogenicity
(International)
embryotropic effect: Change in the embryo and the regulation of its development (#IUPAC)

emesis: Vomiting (#IUPAC)

emission: Release of a substance from a source, including discharges to the wider environment
SN discharge, effluent, release
RT immission (#IUPAC)

emission and exposure control: Technical and administrative procedures and specifications applied for the monitoring, reduction or elimination of emissions from a source or exposure to a target
After WHO, 1989a (#IUPAC)

emission standard: Quantitative limit on the emission or discharge of a substance from a source, usually expressed in terms of a time-weighted average concentration or a ceiling value
PS discharge standard
RT limit value (#IUPAC)

endemic: Present in a community or among a group of people; said of a disease prevailing continually in a region (#IUPAC)

endocrine: Pertaining to hormones or to the glands that secrete hormones directly into the bloodstream (#IUPAC)

endocrine disruptors: Synthetic chemicals and natural plant compounds that may affect the endocrine system (the communication system of glands, hormones and cellular receptors that control the body's internal functions). Many of these substances have been associated with developmental, reproductive and other health problems in wildlife and laboratory animals. Some experts suggest these compounds may affect humans in similar ways. (#CEHN)

endoplasmic reticulum: Intracellular complex of membranes in which proteins and lipids, as well as molecules for export, are synthesized and in which the biotransformation reactions of the mono-oxygenase enzyme systems occur: may be isolated as microsomes following cell fractionation procedures
RT cytochrome P-420, cytochrome P-448, cytochrome P-450, microsome, mono-oxygenase, phase 1 reactions (#IUPAC)

endothelial: Pertaining to the layer of flat cells lining the inner surface of blood and lymphatic vessels, and the surface lining of serous and synovial membranes (#IUPAC)

enteritis: Intestinal inflammation (#IUPAC)

enterohepatic circulation: Cyclical process involving intestinal re-absorption of a substance that has been excreted through the bile followed by transfer back to the liver, making it available for biliary excretion again
After WHO, 1979 (#IUPAC)

environment: Aggregate, at a given moment, of all external conditions and influences to which a system under study is subjected
ISO, 1975 (#IUPAC)

environmental damage: Adverse effects to the natural environment (#IUPAC)

environmental exposure level (EEL): Level (concentration or amount or a time integral of either) of a substance to which an organism or other component of the environment is exposed in its natural surroundings (#IUPAC)

environmental fate: Destiny of a chemical or biological pollutant after release into the natural environment (#IUPAC)

environmental health: Human welfare and its influence by the environment, including technical and administrative measures for improving the human environment from a health point of view
PS environmental medicine, environmental hygiene
RT occupational hygiene
After WHO, 1989a (#IUPAC)

environmental health impact assessment: Estimate of the adverse health effects or risks likely to follow from a proposed or expected environmental change or development (#IUPAC)

environmental health criteria documents: Critical publications of IPCS containing reviews of methodologies and existing knowledge - expressed, if possible, in quantitative terms - of selected substances (or groups of substances) on identifiable, immediate, and long-term effects on human health and welfare.
IPCS, 1978 (#IUPAC)

environmental hygiene: Practical control measures used to improve the basic environmental conditions affecting human health, for example clean water supply, human and animal waste disposal, protection of food from biological contamination, and housing conditions, all of which are concerned with the quality of the human environment
After WHO, 1979
SN environmental sanitation (#IUPAC)

environmental impact assessment (EIA): Appraisal of the possible environmental consequences of a past, ongoing, or planned action, resulting in the production of an environmental impact statement or "finding of no significant impact (FONSI)"
RT environmental impact statement (#IUPAC)

environmental impact statement (EIS): Report resulting from an environmental impact assessment
RT environmental impact assessment (#IUPAC)

environmental justice: The fair treatment of people of all races, cultures, incomes, and educational levels with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies. Fair treatment implies that no population should be forced to shoulder a disproportionate share of the negative environmental impacts of pollution or environmental hazards due to a lack of political or economic strength.(5) (#CEHN)

environmental media: Soil, water, air, biota (plants and animals), or any other parts of the environment that can contain contaminants (#ATSDR)

environmental media and transport mechanism: Environmental media include water, air, soil, and biota (plants and animals). Transport mechanisms move contaminants from the source to points where human exposure can occur. The environmental media and transport mechanism is the second part of an exposure pathway. (#ATSDR)

environmental monitoring: Continuous or repeated measurement of agents in the environment to evaluate environmental exposure and possible damage by comparison with appropriate reference values based on knowledge of the probable relationship between ambient exposure and resultant adverse effects.
RT biological effect monitoring, biological monitoring, reference value (#IUPAC)

environmental protection:
1. Actions taken to prevent or minimize adverse effects to the natural environment
2. Complex of measures including monitoring of environmental pollution, development and practice of environmental protection principles (legal, technical, and hygienic), including risk assessment, risk management and risk communication
(#IUPAC)

environmental quality objective (EQO): Overall state to be aimed for in a particular aspect of the natural environment, for example, "water in an estuary such that shellfish populations survive in good health". Unlike an environmental quality standard, the EQO is usually expressed in qualitative and not quantitative terms
RT environmental quality standard (#IUPAC)

environmental quality standard (EQS): Amount concentration or mass concentration of a substance that should not be exceeded in an environmental system, often expressed as a time-weighted average measurement over a defined period
SN ambient standard
RT limit value (#IUPAC)

environmental sanitation: See SN environmental hygiene ((#IUPAC)

Environmental Tobacco Smoke (ETS): Second hand smoke; tobacco smoke inhaled by someone in proximity to a smoker. (#CEHN)

environmental transformation: Chemical transformation of substances resulting from interactions in the environment (#IUPAC)

enzootic: Present in a community or among a group of animals; said of a disease prevailing continually in a region (#IUPAC)

EPA: United States Environmental Protection Agency (#ATSDR)

epidemiology: Study of the distribution and determinants of health-related states or events in populations and the application of this study to control of health problems
Last, 1988 (#IUPAC)

epidemiologic surveillance: (see Public health surveillance) (#ATSDR)

epigastric: Pertaining to the upper-middle region of the abdomen. epigen/esis n., -etic adj.: Changes in an organism brought about by alterations in the expression of genetic information without any change in the genome itself: the genotype is unaffected by such a change but the phenotype is altered
RT mutation, phenotype, transformation, tumour (#IUPAC)

epileptiform: Occurring in severe or sudden spasms, as in convulsion or epilepsy (#IUPAC)

epithelioma: Any tumour derived from epithelium
NT carcinoma (#IUPAC)

epithelium: Cells covering the internal and external surfaces of the body (#IUPAC)

epitope: Any part of a molecule that acts as an antigenic determinant: a macromolecule can contain many different epitopes each capable of stimulating production of a different specific antibody.
Nagel et al. (eds), 1991 (#IUPAC)

*equivalent diameter *(of a particle): Diameter of a spherical particle of the same density as a particle under investigation that, relative to a given phenomenon or property, would behave in the same way as the particle under investigation
RT aerodynamic diameter
ISO, 1979 (#IUPAC)

erythema: Redness of the skin produced by congestion of the capillaries (#IUPAC)

eschar: Slough or dry scab on an area of skin that has been burnt (#IUPAC)

estimated daily intake (EDI): Prediction of the daily intake of a residue of a potentially harmful agent based on the most realistic estimation of the residue levels in food and the best available food consumption data for a specific population: residue levels are estimated taking into account known uses of the agent, the range of contaminated commodities, the proportion of a commodity treated, and the quantity of home-grown or imported commodities. The EDI is expressed in mg residue per person
WHO, 1989b (#IUPAC)

estimated exposure concentration (EEC): Measured or calculated amount or mass concentration of a substance to which an organism is likely to be exposed, considering exposure by all sources and routes (#IUPAC)

estimated exposure dose (EED): Measured or calculated dose of a substance to which an organism is likely to be exposed, considering exposure by all sources and routes
IRIS, 1986 (#IUPAC)

estimated maximum daily intake (EMDI): Prediction of the maximum daily intake of a residue of a potentially harmful agent based on assumptions of average food consumption per person and maximum residues in the edible portion of a commodity, corrected for the reduction or increase in residues resulting from preparation, cooking, or commercial processing. The EMDI is expressed in mg residue per person
WHO, 1989b (#IUPAC)

etiology: See aetiology (#IUPAC)

eukaryote: Cell or organism with the genetic material packed in a membrane-surrounded structurally discrete nucleus and with well-developed cell organelles. The term includes all organisms except archaebacteria, eubacteria and cyanobacteria (until recently classified as cyanophyta or blue-green algae)
AN prokaryote
Nagel et al. (eds), 1991 (#IUPAC)

European Inventory of Existing Chemical Substances (EINECS): List of all substances supplied either singly or as components in preparations to persons in a Member State of the European Community on any occasion between 1 January 1971 and 18 September 1981 (#IUPAC)

eutrophic: Describes a body of water with a high concentration of nutrient salts and a high or excessive rate of biological production (#IUPAC)

eutrophication: Adverse change in the chemical and biological status of a body of water following depletion of the oxygen content caused by decay of organic matter resulting from high primary production as a result of enhanced input of nutrients (#IUPAC)

excess lifetime risk: Additional or excess risk incurred over the lifetime of an individual by exposure to a toxic substance
BT risk
RT hazard
IRIS, 1986 (#IUPAC)

excess rate: See SN rate difference (#IUPAC)

exchange transfusion: Method of active artificial elimination of toxicity consisting in complete replacement of blood of the patient by donor blood (#IUPAC)

excipient: Any more or less inert substance added to a drug to give suitable consistency or form to the drug
RT vehicle (#IUPAC)

excretion: Discharge or elimination of an absorbed or endogenous substance, or of a waste product, and/or their metabolites, through some tissue of the body and its appearance in urine, faeces, or other products normally leaving the body. Excretion of chemical compounds from the body occurs mainly through the kidney and the gut. Volatile compounds may be largely eliminated by exhalation. Excretion by perspiration and through hair and nails may also occur. Excretion by the gastrointestinal tract may take place by various routes such as the bile, the shedding of intestinal cells and transport through the intestinal mucosa
After WHO, 1989a
RT clearance, elimination (#IUPAC)

excretion rate: Amount of substance (and/or its metabolites) or fraction that is excreted per unit time. It should be noted that according to this definition excretion does not include the passing of a substance through the intestine without absorption. When discussing the total amount of a substance in faeces (including the unabsorbed part), it is preferable to speak about faecal substance content (mol/kg) or mass content (kg/kg) (#IUPAC)

exogenous: Resulting from causes or derived from materials external to an organism
AN endogenous (#IUPAC)

exogenous substance: See SN xenobiotic (#IUPAC)

experimental model ecosystem: See SN microcosm (#IUPAC)

explant: Living tissue removed from its normal environment and transferred to an artificial medium for growth (#IUPAC)

exposed: Subject to a factor that is under study in the environment, for instance an environmental hazard
AN non-exposed, unexposed (#IUPAC)

exposed group (sometimes abbreviated to exposed) in epidemiology: Group whose members have been exposed to a supposed cause of a disease or health state of interest, or possess a characteristic that is a determinant of the health outcome of interest
Last, 1988 (#IUPAC)

exposure:
1. Concentration, amount or intensity of a particular physical or chemical agent or environmental agent that reaches the target population, organism, organ, tissue or cell, usually expressed in numerical terms of substance concentration, duration, and frequency (for chemical agents and micro-organisms) or intensity (for physical agents such as radiation)
2. Process by which a substance becomes available for absorption by the target population, organism, organ, tissue or cell, by any route
(International)
exposure assessment: Process of measuring or estimating concentration (or intensity), duration and frequency of exposures to an agent present in the environment or, if estimating hypothetical exposures, that might arise from the release of a substance, or radionuclide, into the environment
RT risk assessment (#IUPAC)

exposure control: See BT emission and exposure control (International)
exposure-dose reconstruction
A method of estimating the amount of people's past exposure to hazardous substances. Computer and approximation methods are used when past information is limited, not available, or missing ATSDR)
exposure-effect relationship: See NT concentration-effect relationship, dose-effect relationship (#IUPAC)

exposure investigation: The collection and analysis of site-specific information and biologic tests (when appropriate) to determine whether people have been exposed to hazardous substances (#ATSDR)

exposure limit: General term defining an administrative substance concentration or intensity of exposure that should not be exceeded
IPCS, 1978
RT discharge limit (#IUPAC)

exposure pathway: The route a substance takes from its source (where it began) to its end point (where it ends), and how people can come into contact with (or get exposed to) it. An exposure pathway has five parts: a source of contamination (such as an abandoned business); an environmental media and transport mechanism (such as movement through groundwater); a point of exposure (such as a private well); a route of exposure (eating, drinking, breathing, or touching), and a receptor population (people potentially or actually exposed). When all five parts are present, the exposure pathway is termed a completed exposure pathway (#ATSDR)

exposure ratio: In a case control study, value obtained by dividing the rate at which persons in the case group are exposed to the risk factor (or to the protective factor) by the rate at which persons in the control group are exposed to the risk factor (or to the protective factor) of interest
After Last, 1988 (#IUPAC)

exposure registry: A system for collecting and maintaining in a structured record information on persons with documented environmental exposure(s). The exposure registry evolved from the need for fundamental information concerning the potential impact on human health of long-term exposure to low and moderate levels of hazardous substances.(2) (#CEHN)

exposure-response relationship: See RT concentration-response relationship, dose-response relationship (#IUPAC)

exposure test: Determination of the level, concentration or uptake of a potentially toxic compound and/or its metabolite(s) in biological samples from an organism (blood, urine, hair etc.) and the interpretation of the results to estimate the absorbed dose or degree of environmental pollution; or the measuring of biochemical effects, usually not direct adverse effects of the substance, and relating them to the quantity of substance absorbed, or to its concentration in the environment
RT biological monitoring, biological assessment of exposure
IRPTC, 1982 (#IUPAC)

external validity: Generalizability of the results of a particular study, beyond the limits of the population actually studied
BT validity
IPCS, 1978 (#IUPAC)

extra risk: Probability that an agent produces an observed response, as distinguished from the probability that the response is caused by a spontaneous event unrelated to the agent
IRIS, 1986
BT risk (#IUPAC)

extraneous residue limit (ERL): Refers to a Pesticide residue or contaminant arising from environmental sources (including former agricultural uses) other than the use of a pesticide or contaminant substance directly or indirectly on the commodity. It is the maximum concentration of a pesticide residue or contaminant that is recommended by the Codex Alimentarius Commission to be legally permitted or recognized as acceptable in or on food, agricultural commodity or animal feed. The mass content is expressed in milligrams of pesticide residue or contaminant per kilogram of commodity
After Codex Alimentarius Commission, 1986 (#IUPAC)

extrapolation: Calculation, based on quantitative observations in exposed test species or in vitro test systems, of predicted dose-effect and dose-response relationships for a substance in humans and other biota including interspecies extrapolations and extrapolation to susceptible groups of individuals: the term may also be used for qualitative information applied to species or conditions that are different from the ones in which the original investigations were carried out (#IUPAC)

F


FDA: See "U.S. Food and Drug Administration". (#Glossary)

feasibility study: A study by EPA to determine the best way to clean up environmental contamination. A number of factors are considered, including health risk, costs, and what methods will work well. (#ATSDR)

fecundity:
1. Ability to produce offspring frequently and in large numbers.
2. In demography, the physiological ability to reproduce.
(International)
feromone: See SN pheromone (#IUPAC)

fertility: Ability to conceive and to produce offspring: for litter- bearing species the number of offspring per litter is used as a measure of fertility. Reduced fertility is sometimes referred to as subfertility.
USEPA, 1989
RT fecundity (#IUPAC)

fertility toxicant: Produces abnormalities of male or female reproductive functions or impairs reproductive capacity.
RT developmental toxicity, reproductive toxicant.
USEPA, 1986 (#IUPAC)

fertilizer: Substance applied to soil or hydroponic systems for improving the root nutrition of plants with the aim of increasing crop yields and/or controlling production (#IUPAC)

fetotoxicity: Toxicity to the fetus.
RT embryotoxicity,teratogenicity (#IUPAC)

fetus (often incorrectly foetus): Young mammal within the uterus of the mother from the visible completion of characteristic organogenesis until birth: in humans, this period is usually defined as from the third month after fertilisation until birth (prior to this, the young mammal is referred to as an embryo).
RT embryo.
Oxford English Dictionary, 1991 (#IUPAC)

fibrosis: Abnormal formation of fibrous tissue (#IUPAC)

fiducial limit: Form of confidence limit given as a stated probability, for example P = 0.95: in toxicology the terms fiducial limits and confidence limits are generally considered to be synonymous.
Brown, 1988 (#IUPAC)

first-pass effect: Biotransformation of a substance in the liver after absorption from the intestine and before it reaches the systemic circulation (#IUPAC)

fixed dose procedure: Acute toxicity test in which a substance is tested initially at a small number (3 or 4) predefined doses to identify which produces evident toxicity without lethality: the test may be repeated at one or more higher or lower defined discriminating doses to satisfy the criteria.
NT limit test (#IUPAC)

fluorosis: Adverse effects of fluoride, as in dental or skeletal fluorosis (#IUPAC)

foci (singular focus): Small groups of cells distinguishable, in appearance or histochemically, from the surrounding tissue: indicative of an early stage of a lesion that may lead to the formation of a neoplastic nodule (#IUPAC)

foetus: See fetus (#IUPAC)

follow-up study: Investigation in which individuals or populations, selected on the basis of whether they have been exposed to risk, have received a specified preventive or therapeutic procedure, or possess a certain characteristic, are followed to assess the outcome of exposure, the procedure, or effect of the characteristic, for example, occurrence of disease.
SN cohort study.
Last, 1988 (#IUPAC)

food additive: Any substance not normally consumed as a food by itself and not normally used as a typical ingredient of the food, whether or not it has nutritive value, the intentional addition of which to food for a technological (including organoleptic) purpose in the manufacture, processing, preparation, treatment, packing, packaging, transport or holding of such food results, or may be reasonably expected to result (directly or indirectly) in it or its byproducts becoming a component of or otherwise affecting the characteristics of such foods. The term does not include "contaminants" or substances added to food for maintaining or improving nutritional qualities.
Codex Alimentarius Commission, 1983 (#IUPAC)

food allergy: Hypersensitivity reaction to substances in the diet to which an individual has previously been sensitised.
BT allergy, hypersensitivity.
RCP, 1984
(#IUPAC)

food chain: Sequence of transfer of matter and energy in the form of food from organism to organism in ascending or descending trophic levels.
WHO, 1979 (#IUPAC)

food intolerance: Physiologically based reproducible, unpleasant (adverse) reaction to a specific food or food ingredient that is not immunologically based.
RCP, 1984
RT food allergy (#IUPAC)

food web: Network of food chains (#IUPAC)

forced diuresis: Method of stimulating diuresis based on performing hydrational therapy, sometimes with parallel introduction of diuretics, with the aim of achieving increased clearance of a toxic substance in rine (#IUPAC)

foreign substance (foreign compound): See SN xenobiotic (#IUPAC)

frame-shift mutation: Point mutation involving either the deletion or insertion of one or two nucleotides in a gene: by the frame shift mutation, the normal reading frame used when decoding nucleotide triplets in the gene is altered.
After Nagel et al. (eds), 1991 (#IUPAC)

fumigant: Substance that is vaporized in order to kill or repel pests (#IUPAC)

fungi: (Singular: Fungus) Molds, mildews, yeasts, mushrooms, and puffballs. A group of organisms lacking in chlorophyll (i.e., are not photosynthetic) and which are usually non-mobile, filamentous, and multicellular. Some grow in soil, others attach themselves to decaying trees and other plants which they obtain nutrients. Some are pathogens, others stabilize sewage and digest composted waste.(1) (#CEHN)

fungicide: Substance intended to kill fungi (#IUPAC)

fungus preparation: Substance obtained from fungi that has an insecticidal effect reflecting the pathogenicity of the fungi for insects.
IRPTC, 1982 (#IUPAC)

G


gamete: Reproductive cell (either sperm or egg) containing a haploid set of chromosomes.
RT zygote (#IUPAC)

gametocide: Substance intended to kill gametes (#IUPAC)

gastrointestinal: Pertaining or communicating with the stomach and intestine (#IUPAC)

gavage: Administration of materials directly into the stomach by oesophageal intubation (#IUPAC)

gene: Structurally a basic unit of hereditary material; an ordered sequence of nucleotide bases that encodes one polypeptide chain (following transcription to mRNA).
SN cistron (#IUPAC)

gene amplification: Production of extra copies of a chromosomal sequence found either as intra- or extra-chromosomal DNA; with respect to a plasmid, it refers to the increase in the number of plasmid copies per cell induced by a specific treatment of transformed cells (#IUPAC)

genetic polymorphism: Condition in which a genetic character occurs in more than one form, resulting in the coexistence of more than one morphological type in a given population (#IUPAC)

genetic toxicology: Study of substances that can produce adverse heritable changes (#IUPAC)

genome: Complete set of chromosomal and extrachromosomal genes of an organism, a cell, an organelle, or a virus: complete DNA component of an organism.
Nagel et al. (eds), 1991 (#IUPAC)

genotoxicity: Ability to cause damage to genetic material. Such damage may be mutagenic and/or carcinogenic (#IUPAC)

genotype: Genetic constitution of an organism as revealed by genetic or molecular analysis; the complete set of genes, both dominant and recessive possessed by a particular organism, cell, organelle or virus.
After Nagel et al. (eds), 1991 (International)
[Geographic Information System (GIS): A mapping system that uses computers to collect, store, manipulate, analyze, and display data. For example, GIS can show the concentration of a contaminant within a community in relation to points of reference such as streets and homes. (ATSDR)
germ-free animal: Animal grown under sterile conditions in the period of postnatal development: such animals are usually obtained by Caesarean operation and kept in special sterile boxes in which there are no viable micro-organisms (sterile air, food and water are supplied).
SN axenic animal.
BT gnotobiont, gnotobiote.
IRPTC, 1982 (#IUPAC)

germinal aplasia: Complete failure of gonad development (#IUPAC)

glomerular: Pertaining to a tuft or cluster, as of a plexus of capillary blood vessels or nerve fibres, especially referring to the capillaries of the glomeruli of the kidney (#IUPAC)

"glue sniffing": Solvent abuse using plastic cement or other solvent-based adhesives.
BT "solvent sniffing".
RT addiction, dependence, solvent abuse (#IUPAC)

gnotobiont: See SN gnotobiote.
NT germ-free animal (#IUPAC)

gnotobiota: Specifically and entirely known microfauna and microflora of a specially reared laboratory animal.
RT gnotobiote (#IUPAC)

gnotobiote: Specially reared laboratory animal whose microflora and microfauna are specifically known in their entirety.
NT germ-free animal (#IUPAC)

gonadotropic: Pertaining to effects on sex glands and on the systems that regulate them (#IUPAC)

good agricultural practice (GAP) in the use of pesticides: Nationally authorised safe uses of pesticides under actual conditions necessary for effective and reliable pest control. It encompasses a range of levels of pesticide applications up to the highest authorized use, applied in a manner that leaves a residue which is the smallest amount practicable. Authorized safe uses include nationally registered or recommended uses, that take into account public and occupational health and environmental safety considerations. Actual conditions include any stage in the production, storage, transport, distribution, and processing of food commodities and animal feed.
Codex Alimentarius Commission, 1989 (#IUPAC)

good laboratory practice (GLP) principles: Fundamental rules incorporated in national regulations concerned with the process of effective organization and the conditions under which laboratory studies are properly planned, performed, monitored, recorded, and reported.
RT quality assurance, quality control (#IUPAC)

good manufacturing practice (GMP) principles: Fundamental rules incorporated in national regulations concerned with the process of effective organization of production and ensuring standards of defined quality at all stages of production, distribution and marketing; minimization of waste and its proper disposal are part of this process (#IUPAC)

graded effect: Consequence that can be measured on a graded scale of intensity or severity and its magnitude related directly to the dose or concentration of the substance producing it.
After WHO, 1989a
AN all-or-none effect, quantal effect.
RT stochastic effect (#IUPAC)

gradient: The change in a property over a certain distance. For example, lead can accumulate in surface soil near a road due to automobile exhaust. As you move away from the road, the amount of lead in the surface soil decreases. This change in the lead concentration with distance from the road is called a gradient. (#Glossary)

grand rounds: Training sessions for physicians and other health care providers about health topics (#ATSDR)

granuloma: Granular growth or tumor, usually of lymphoid and epithelial cells (#IUPAC)

greenhouse effect: The warming of the Earth's atmosphere attributed to a build-up of carbon dioxide or other gases; some scientists think that this build-up allows the sun's rays to heat the Earth, while infrared radiation makes the atmosphere opaque to a counterbalancing loss of heat.(1) (#CEHN)

groundwater: Water beneath the earth's surface in the spaces between soil particles and between rock surfaces (compare with surface water) (ATSDR)
ground treatment of plants: Dusting or spraying of plants with pesticides by hand, by special machines, or by apparatus fixed to tractors or driven by them.
IRPTC, 1982 (#IUPAC)

guideline for exposure limits: Scientifically judged quantitative value (a concentration or number) of an environmental constituent that ensures aesthetically pleasing air, water or food and from which no adverse effect is expected concerning noncarcinogenic endpoints, or that gives an acceptably low estimate of lifetime cancer risk from those substances which are proven human carcinogens or carcinogens with at least limited evidence of human carcinogenicity. (#IUPAC)

guideline value: Quantitative measure (a concentration or a number) of a constituent of an environmental medium that ensures aesthetically pleasing air, water, or food and does not result in a significant risk to the user. (#IUPAC)

guides to air quality: Sets of atmospheric concentrations and exposure times that are associated with specific effects of varying degrees of pollution on man, animals, vegetation, and the environment in general.
WHO, 1979 (#IUPAC)

guides to environmental quality: Sets of concentrations, numbers and exposure times that are associated with the specific effects of factors in environmental media on man, animals, vegetation, and the environment in general.
After WHO, 1979 (#IUPAC)

guinea-pig maximisation test (Magnusson and Kligman test): Widely used skin test for screening possible contact allergens: considered to be a useful method to identify likely moderate and strong sensitizers in humans (#IUPAC)

H


haematemesis: Vomiting of blood (#IUPAC)

haematoma: Localised accumulation of blood, usually clotted, in an organ, space, or tissue, due to a failure of the wall of a blood vessel (#IUPAC)

haematuria: Presence of blood in the urine (#IUPAC)

haemodialysis: Use of an artificial kidney to remove toxic compounds from the blood by passing it through a tube of semipermeable membrane. The tube is bathed in a dialysing solution to restore the normal chemical composition of the blood while permitting diffusion of toxic substances from the blood. (#IUPAC)

haemoglobinuria: Presence of free haemoglobin in the urine (#IUPAC)

haemolysin: Substance that damages the membrane of erythrocytes causing the release of haemoglobin (#IUPAC)

haemolysis: Release of haemoglobin from erythrocytes, and its appearance in the plasma (#IUPAC)

haemoperfusion: Passing blood through a column of charcoal or adsorbent resin for the removal of drugs or toxins (#IUPAC)

haemosiderin: Iron-containing pigment that is formed from haemoglobin released during the disintegration of red blood cells and that accumulates in individuals who have ingested excess iron (#IUPAC)

half-life (half-time) (t1/2): Time in which the concentration of a substance will be reduced by half, assuming a first order elimination process or radioactive decay (#IUPAC)

haploid (monoploid): State in which a cell contains only one set of chromosomes.
RT diploid, gamete, meiosis (#IUPAC)

hapten: Low-molecular-weight molecule that contains an antigenic determinant (epitope) that may bind to a specific antibody but which is not itself antigenic unless complexed with an antigenic carrier such as a protein or cell; once bound it can cause the sensitization of lymphocytes, possibly leading to allergy or cell-mediated hypersensitivity.
After Nagel et al. (eds), 1991
RT allergy, antigen, antibody, cell-mediated hypersensitivity, epitope (#IUPAC)

harm: Damage or adverse effect to a population, species, individual organism, organ, tissue or cell.
SN adverse effect (#IUPAC)

harmful occupational factor: Component of the work environment the effect of which on a worker under certain conditions leads to ill health or reduction of working ability (#IUPAC)

harmful substance: Substance that, following contact with an organism can cause ill health or adverse effects either at the time of exposure or later in the life of the present and future generations.
SN noxious substance (#IUPAC)

hazard: Set of inherent properties of a substance, mixture of substances or a process involving substances that, under production, usage or disposal conditions, make it capable of causing adverse effects to organisms or the environment, depending on the degree of exposure; in other words, it is a source of danger.
RT risk (#IUPAC)

hazard assessment: Determination of factors controlling the likely effects of a hazard such as the dose-effect and dose-response relationships, variations in target susceptibility, and mechanism of toxicity.
RT exposure assessment, hazard evaluation, hazard identification, risk assessment, risk characterization, risk estimation, risk evaluation, risk identification, risk perception (#IUPAC)

hazard communication standard: US OSHA standard requiring all employers to inform employees of the hazard of substances in the workplace and the steps necessary to avoid harm (#IUPAC)

hazard evaluation: Establishment of a qualitative or quantitative relationship between hazard and benefit, involving the complex process of determining the significance of the identified hazard and balancing this against identifiable benefit: this may subsequently be developed into a risk evaluation.
RT exposure evaluation, hazard assessment, hazard identification, risk assessment, risk characterization, risk estimation, risk evaluation, risk identification,[ risk perception|http://sis.nlm.nih.gov/enviro/glossaryr.html#riskperception] (#IUPAC)

hazard identification: Determination of substances of concern, their adverse effects, target populations, and conditions of exposure, taking into account toxicity data and knowledge of effects on human health, other organisms and their environment.
WHO, 1988 (#IUPAC)

hazard quotient (HQ): Ratio of toxicant exposure (estimated or measured) to a reference value regarded as corresponding to a threshold of toxicity: if the total hazard quotient from all toxicants to a target exceeds unity, the combination of toxicants may produce (will produce under assumptions of additivity) an adverse effect.
RT hazard, pollutant, toxic substance (#IUPAC)

hazardous production factor: Production factor the effect of which on a worker under certain conditions results in injury or some impairment of health.
SN hazard at work, hazardous occupational factor.
IRPTC, 1982 (#IUPAC)

Hazardous Substance Release and Health Effects Database (HazDat): The scientific and administrative database system developed by ATSDR to manage data collection, retrieval, and analysis of site-specific information on hazardous substances, community health concerns, and public health activities. (#ATSDR)

hazardous waste: Potentially harmful substances that have been released or discarded into the environment (#ATSDR)

hazardous waste landfill: An excavated or engineered site where hazardous waste is deposited and covered.(1) (#CEHN)

health:
1. State of complete physical, mental and social well-being, and not merely the absence of disease or infirmity.
WHO, 1978b
2. State of dynamic balance in which an individual's or a group's capacity to cope with the circumstances of living is at an optimal level.
3. State characterized by anatomical, physiological and psychological integrity, ability to perform personally valued family, work and community roles; ability to deal with physical, biological, psychological and social stress; a feeling of wellbeing; and freedom from the risk of disease and untimely death.
Last, 1988
(International)
health-based exposure limit: Maximum concentration or intensity of exposure that can be tolerated without significant effect (based on only scientific and not economic evidence concerning exposure levels and associated health effects).
de Koning, 1987, ACGIH 1975 (International)
health consultation: A review of available information or collection of new data to respond to a specific health question or request for information about a potential environmental hazard. Health consultations are focused on a specific exposure issue. Health consultations are therefore more limited than a public health assessment, which reviews the exposure potential of each pathway and chemical (compare with public health assessment). (#ATSDR)

health education: Programs designed with a community to help it know about health risks and how to reduce these risks (#ATSDR)

health effects studies related to contaminants: Studies of the health of people who may have been exposed to contaminants. They include, but are not limited to, epidemiological studies, reviews of health status of people in exposure or disease registries, and doing medical tests. (#Glossary)

health hazard: Any factor or exposure that may adversely affect health.
Last, 1988 (#IUPAC)

health investigation: The collection and evaluation of information about the health of community residents. This information is used to describe or count the occurrence of a disease, symptom, or clinical measure and to evaluate the possible association between the occurrence and exposure to hazardous substances. (#ATSDR)

health promotion: The process of enabling people to increase control over, and to improve, their health (#ATSDR)

health statistics review: The analysis of existing health information (i.e., from death certificates, birth defects registries, and cancer registries) to determine if there is excess disease in a specific population, geographic area, and time period. A health statistics review is a descriptive epidemiologic study. (#ATSDR)

health surveillance: Periodic medico-physiological examinations of exposed workers with the objective of protecting health and preventing occupationally related disease.
Berlin, Yodaiken, and Henman, 1984
RT biological monitoring, biomarker, monitoring (#IUPAC)

healthy worker effect: Epidemiological phenomenon observed initially in studies of occupational diseases: workers usually exhibit lower overall disease and death rates than the general population, due to the fact that the old, severely ill and disabled are ordinarily excluded from employment. Death rates in the general population may be inappropriate for comparison, if this effect is not taken into account.
WHO, 1989a (#IUPAC)

heavy metals: Metallic elements with high atomic weights, e.g., mercury, chromium, cadmium (cd), arsenic, and lead; can damage living things at low concentrations and tend to accumulate in the food chain.(1) (#CEHN)

hepatic: Pertaining to the liver (#IUPAC)

hepatotoxicp

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