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Arsenic

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*Also see our longer, updated article on arsenic, adapted from A Small Dose of Toxicology by Dr. Steven Gilbert.

 

Physical Information

Name: Arsenic

Use: wood preservative, Pesticides, semiconductor manufacturing

Source: coal combustion, drinking water, environment, medical drugs, seafood

Recommended daily intake: none (not essential)

Absorption: inhalation, intestine - inorganic high, organic low, skin

Sensitive individuals: children

Toxicity/symptoms: peripheral nervous system (tingling in hands and feet), skin cancer (ingestion), lung cancer (inhalation), hyperpigmentation (keratosis) of palms and soles; vascular complications

Regulatory facts:

  • EPA - drinking water 10 ug/L (0.01 ppm)
  • EPA - RfD - 0.3 ug/kg/ day
  • OSHA - Workplace air 10 ug/m3
  • ATSDR - MRL - 0.3 ug/kg/day

General facts: long history of use as medicine and poison

Environmental: global environmental contaminant, bioaccumulates in fish and shellfish (mostly in a form that is not harmful)

Recommendations: avoid, do not use treated lumber, test drinking water

Overview


Arsenic has long been known for its use as a poison. Cesare Borgia and his family used arsenic to consolidate power in 16th century Italy and it is rumored that Napoleon Bonaparte may have been poisoned with arsenic.

From emedicine:
Arsenic has been used as a medicinal agent, a pigment, a pesticide, and an agent of criminal intent. It is typically considered a heavy metal and shares many toxic characteristics with the other heavy Metals (eg, Lead, Mercury). Arsenic is primarily used in the production of glass and semiconductors. It is also found in certain water supplies and seafood.

Arsenic exposure today most often results from industrial practices such as the smelting process and overexposure to treated wood.

Chemical Description


Arsenic is a versatile metal, forming various compounds, inorganic or organic, with a complex chemistry. Inorganic arsenic is widely distributed in nature, usually in the trivalent form (As3+) bet also pentavalent arsenic (As5+). The trivalent forms include arsenic trioxide, sodium arsenite, and arsenic trichloride. Organic arsenic is much less toxic than inorganic and it is produced in a biomethylation process by many organisms including shellfish and humans. It bioaccumulates in fish and shellfish (mostly in a form that is not harmful).

Arsenic is also very similar to Phosphorous.

Arsenic in Drinking Water


Arsenic Poisoning from drinking water remains a very serious world health issue. Internationally, in West Bengal, India and Bangladesh more than 75 million people are exposed to arsenic-laden drinking water that threatens their health. Of those 75 million, it is estimated that 200,000 to 270,000 people will die from cancer each year (#Gilbert, 2004.

High levels of arsenic in drinking water often results from high levels of arsenic in nearby soil or rocks. The US EPA has recently taken a tougher stance on arsenic by lowering the standard from 50 ppm to 10 ppm.

Arsenic in the Environment


Arsenic is a ubiquitous element in the natural environment. It is a naturally occurring metal and its organic form, where it is combined with carbon or hydrogen, is not as common as inorganic arsenic, where arsenic is combined with one or more elements including oxygen, Chlorine, and sulfur. The amount of arsenic released from ore bodies is mush less than the amount of arsenic released due to human activity.

All rocks and soil contain some level of arsenic. Most rocks contain between 1-5 ppm or arsenic and this arsenic leaches into the soil. The rocks also leach arsenic into groundwater sources and depending on the type of rocks, arsenic can build up to critical levels in some sources. Up to 40 million people are at risk of drinking arsenic laden water in Bangladesh.

The majority of arsenic released into the environment is from the industrial smelting or coal burning processes. By burning arsenic-containing ores, smoke that is inundated with arsenic travels downwind and settles in the soil or water (#Roy and Saha, 2002).

Arsenic has been used as an herbicide and insecticide in the past so the areas where it was applied, most commonly orchards, possess elevated levels. Soil in areas surrounding gold, copper, and zinc mines are often have the highest concentrations of arsenic.

Uses


Insecticide
Different forms of arsenic have been used as Insecticides (lead hydrogen arsenate on fruit trees and later monosodium methyl arsenate). Using arsenic as an insecticide has caused elevated levels in the soil in areas where it was applied in the past.

Poison
Main article: Arsenic Poisoning
Arsenic also has been used in the past as a poison.

Treated Wood
The compound used is the Pesticide chromated copper arsenate (CCM). CCM is a tonic of inorganic salts of chromium, Copper, and arsenate that is forced into the wood under intense pressure. This wood has traditionally been used in decks, playground equipment, outdoor furniture and fences, construction lumbar, pilings, poles, and other structures where wood will be exposed to the elements. A standard 8 foot 2 x 4 can have up to 15 grams of arsenic.

Though the health effects of treated wood have been debated by the government, environmental agencies, and the lumber industry, research has shown that treated wood can be a significant course of arsenic exposure. The biggest hazard is if one inhales sawdust from treated wood. Also, research has shown that the arsenic can leach from the wood or be rubbed off the surface. Therefore, children who are in contact with this wood are at a high risk as well.

Manufacturers of this wood reached an agreement with the Environmental Protection Agency to phase out residential use of treated wood but still use it for commercial purposes.

Medical Uses
Many different arsenic compounds have been used, some until quite recently, in medicine throughout the world. Potassium arsenite, arsenic iodide, and arsenic trichloride were used regularly to treat a range of illnesses and arsphenamine was the main drug used to treat syphilis. Arsenic trioxide was the main ingredient of the popular tonic of the 19th century, Fowler's Solution (#Roy and Saha, 2002).

Arsenic is still used in some places in India to control blood counts of patients with hematological malignancies and in many different herbal remedies in China (#Roy and Saha, 2002).

Toxicity


The Agency for Toxic Substances and Registry (ATSDR) of the United States ranked arsenic first in its list of the twenty most hazardous substances. Its toxicity is hard to investigate because of its ability to convert between oxidation states and organometalloidal forms (#Roy and Saha, 2002). The symptoms of exposure, both acute and chronic, are highlighted below.

Health Effects


Main Article: Arsenic Poisoning
The acute effects of inorganic Arsenic Poisoning are well known because of the high number of suicides and poisonings involving arsenic. Ingestion of 70-180 mgs of arsenic can be fatal, but the initial effects may be delayed for hours. The symptoms following oral ingestion include throat constriction and difficulty breathing and swallowing, severe intestinal pain, vomiting, diarrhea, muscle cramps, severe thirst, coma, and death.

The symptoms of chronic arsenic exposure are often associated with contaminated drinking water. The earliest sign of exposure are a garlic odor on the breath, extreme perspiration, muscle tenderness and weakness, and changes in skin pigmentation. More progressive signs include anemia, reduced sensation in the hands and feet from damage to the peripheral nervous system (stocking and glove syndrome), peripheral vascular disease, skin changes on palms and soles, and liver and kidney involvement. Changes in circulation can eventually lead to gangrenous afflictions. Hyperpigmentation and hyperkeratosis of palms and soles occurs in 3-6 months with repeated ingestion of 0.4 mg/kg per day. Therefore, repeated low levels of arsenic exposure can result in conditions similar to acute poisoning.

Classifying arsenic as a carcinogen has been difficult because it does not cause cancer in rodents, but has been shown to cause cell proliferation, chromosome abnormalities, and modification of gene expression (#Roy and Saha, 2002). Therefore its carcinogenicity was not able to independently verified in testing on lab animals, though studies on human cells and then observations of people who have been exposed to increased levels of arsenic (many in West Bengal, India and Bangladesh) have led to a widespread belief in the scientific community that arsenic is in fact a carcinogen (#Roy and Saha, 2002).

Precautions


There are many ways to reduce exposure to arsenic:

  • Wash hands and face and those of children after playing outside and before eating.
  • Clean surfaces in the home regularly using a damp mop or cloth.
  • Avoid bringing dirt into the house. Leave shoes at the door.
  • Brush pets often to minimize the dust they bring into the house.
  • Keep children's toys and play areas clean and discourage mouthing activities, such as eating dirt or sucking on dirty objects.
  • Wash all vegetables thoroughly and peel root crops.
  • Wear gloves and masks if digging or excavating.
  • Use water filters to limit the amount of arsenic in drinking water.
  • Reduce exposure to treated wood.
  • Do not burn treated wood.

Current Events


March 14, 2008
Arsenic-bearing children's drinks produced in United States find their way to Canadian store shelves. See full Ottawa Citizen article

September 14, 2006
Experts have testified to say arsenic has been shown to be a carcinogen. Article is from March 10, 2007 Baltimore Sun.

September 3, 2006
South Bend, Indiana may face huge costs in removing arsenic from local waterway. See South Bend Tribune article

Regulations


Arsenic regulations were set in 1903 in England around at around 90 ppb though this level was decreased by half in the next century when the United States, England, and Bangladesh (see Arsenic Poisoning in Bangladesh for an overview of their arsenic-related problems) all set the arsenic level ceiling at around 50 ppb (#Harvard, 2007). Later this number was reduced again to around 10 ppb.

History


Arsenic has a long and diverse history of use. It is undoubtedly most well known as a poison, having been used since the Romans to the mid-19th century. Its lack of color, odor, and taste made it a favorite means of disposing of one's enemy by merely putting a few drops in a wine glass. When ingested in high quantities, it causes severe abdominal cramps, diarrhea and vomiting, and eventually death. But it can also be administered in small doses, making the victim look as if he/she is suffering from some chronic illness and thus disguising the assassin's intent. Arsenic poisoning was such a widespread concern, the Roman Consul Lucius Cornelious Sulla issued the Lex Cornelia in 82 B.C. outlawing poisoning.

Though Sulla was the first to make Arsenic Poisoning illegal, the Borgias, led by Cesere Borgia and his father Pope Alexander VI, assassinated numerous wealthy cardinals and popes and, by church law, received the deceased holdings and money. They used these practices to become some of the richest men in all of Italy, until they themselves succumbed to the poison.

Additionally, arsenic was used in many tonics and medicines. The most well-known tonic was [Fowler's Solution, which contained one-percent potassium arsenite and was widely used as cure-all through the 19th century. Arsenic was also briefly used as a chemical weapon. The Germans developed the blister agent lewescite, though it was never employed in battle.

Teaching Resources


Powerpoint presentation on Arsenic

External Links


European, Asian, and International Agencies



Non-Government Organizations


  • Arsenic Crisis Information Center - Arsenic in West Bengal & Bangladesh. Online. (accessed: 9 April 2003).
    Site has information and pictures related to arsenic poisoning in West Bengal and Bangladesh.
  • Harvard University. Online. (accessed: 9 April 2003).
    Site has information on health effects of chronic arsenic poisoning.
  • Arsenic: A Murderous History. Dartmouth toxic metals research program. (Accessed: June 30, 2003). A great historical look at the use of arsenic a poison.

References



Harvard Arsenic Foundation. "Chronic Arsenic Poisoning: History, Study and Remediation". Accessed 4-26-07.

Washington State Dept. of Health Report on Arsenic in the Environment.

University of Otago Geology Report on Arsenic int he Environment

Water Arsenic Exposure and Children's Intellectual Function in Araihazar, Bangladesh (2004) Gail A. Wasserman, X. Liu, F. Parvez, H. Ahsan, P Factor-Litvak, A. van Geen, V. Slavkovich, N. J. LoIacono, Z. Cheng, I. Hussain,5 H. Momotaj, and J. Graziano. Environ Health Perspect 112:1329-1333 (2004). EHP Online. (accessed: 14 December 2004)

Environmentally healthy homes and communities. Children's special vulnerabilities. (2001). Am Nurse, 33(6), 26-38; quiz 39-40.


Gilbert, Steven G. "A Small Dose of Toxicology: The Health Effects of Common Chemicals." New York: CRC Press, 2004.

Hall, A. H. (2002). Chronic arsenic poisoning. Toxicol Lett, 128(1-3), 69-72.

Jiang, J. Q. (2001). Removing arsenic from groundwater for the developing world--a review. Water Sci Technol, 44(6), 89-98.

Liu, J., Zheng, B., Aposhian, H. V., Zhou, Y., Chen, M. L., Zhang, A., & Waalkes, M. P. (2002). Chronic arsenic poisoning from burning high-arsenic-containing coal in Guizhou, China. Environ Health Perspect, 110(2), 119-122.

Pott, W. A., Benjamin, S. A., & Yang, R. S. (2001). Pharmacokinetics, metabolism, and carcinogenicity of arsenic. Rev Environ Contam Toxicol, 169, 165-214.


Pradosh Roy and Anupama Saha, A Human Carcinogen",
Current Science 82, (January 2002), p. 38-45.

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