Overview

The purpose of a pesticide is to destroy some form of life, most common types of pesticides are insecticides, herbicides, fungicides, rodenticides, antimicrobials.

Natural pesticides, isolated and harvested from plants possessing some desirable quality, have been used for centuries. Since World War II, a myriad of synthetic compounds have been developed to eliminate pests. The most widespread use of pesticides is in agriculture to produce greater yields, but they have many other uses as well.

Pharmacology and Metabolism

Pesticide use illustrates the basic principles of toxicology: dose-response and individual sensitivity. A small dose is fatal to an insect because of its small size and rate of metabolism. But the same dose will have little effect on a rodent, and an even smaller effect on humans. However, this is the same principle that makes children more vulnerable than adults.

Pesticides work by interfering with some basic biological function essential for life, and because living organisms share many biological mechanisms, pesticides are never specific to just one species. While killing true pest, pesticides also kill other organisms that are tertiary to the goal.

The pesticides are enter the subject, then spread rapidly through the blood system and cause adverse effects that kill or incapacitate the pest. Each pesticide has different qualities and should be looked at specifically to see the biological functions of each.

They can be absorbed in one of four ways. Either dermal, oral, inhalation, or eyes. By far the most exposures result from dermal exposure.

Uses and Benefits

Pesticides are used to control, kill, or mitigate pests. They are used in this manner for a number of reasons, most commonly to increase agricultural yield by eliminating those things which dampen production. They are also used to control the spread of diseases. Such is the case with DDT which eliminates mosquitoes that carry vector-borne diseases such as malaria and typhus.

One dollar spent on pesticides yields $4 of crops saved in return therefore, the $4 billion a year spent on pesticides saves $16 billion in crops. However, most studies do not take into effect the social, environmental, and health effects of pesticides. Many of these are hard to quantify (ie. How much is a human life who died from pesticide induced cancer worth?) but studies have placed what they can quantify at $8 billion a year. Actual costs to society are much greater, but are extremely difficult to quantify. When one considers these costs, the economic effectiveness of pesticides are called into question.

Health Effects

On Humans
A broad spectrum of adverse health effects accompany the use of pesticides. For information regarding a specific pesticide, search the [Pesticide List].

There are three important health-related issues of all pesticides: (1) Worker safety. (2) effects on children, (3) unintended effects on other species and the environment. The crutch of these problems are the common biological systems that many living things share and pesticides, no matter how well planned, cannot target one species and effect unintended organisms, including humans. The World Health Organization estimates that there are 3 million cases of pesticide poisoning each year with up to 220,000 deaths. Children are especially vulnerable to the harmful effects of pesticides.

The neurological effects of pesticide poisoning include memory loss, loss of coordination, reduced speed of response, reduced visual ability, altered or uncontrollable mood and general behavior, and reduced motor skills and such physical afflictions as asthma, allergies, and hypersensitivity. Chronic exposure to pesticides can result in additional neurological effects and increased risk of cancer.

The inert ingredients (ie. not active ingredients) in pesticides, that are easily absorbed through inhalation and the skin, are not thoroughly tested nor are they thoroughly disclosed on the products. Their effects are not known yet they are still widely used.

Health problems in humans arise mostly in farm workers and others that regularly handle pesticides, not consumers of pesticide-laden products.

On the Environment
The effects of pesticides are devastating to the natural world and often counter productive. Pesticide run-off into streams and lakes is a universal problem. The pesticides themselves devastate fish communities and kill anywhere from 6-14 million fish per year (this estimate is conservative because only 80% of the large scale fish deaths are investigated). They also can cause [algae blooms] which deprive the organisms of necessary oxygen.

Pesticides are similarly problematic in countless other organisms. Organochlorines such as DDT, Dioxin, and Agent Orange did perverse damage to everything from birds to other helpful insects to people.

Pesticides are also counterproductive. Though there is no argument that they do not increase yield and profit, there is a strong argument that when all the social and environmental costs are taken into account, the economic efficiency of pesticide use. See [______].

Types

• Insecticides
• Herbicides
• Fungicides
• Rodenticides
• Antimicrobials
  

List of Pesticides

Regulation

Pesticides are regulated on a case by case basis. The Environmental Protection Agency requires all pesticides to be tested and registered.

History

Pesticides have been used for over a thousand years to mitigate damage to crops. One of the first pesticides was sulfur, used by the Chinese in 1000 BC to control bacteria and mold. It is still used in the wine industry to control unwanted growth and yeast after barreling. The Chinese also began using arsenic-containing compounds as pesticides. Throughout the 1800s arsenic trioxide was used to control weed growth and lead arsenate was an important [insecticide], particularly on orchards. Some of the first concerns about pesticides were raised over lead arsenate residue on fruits and many orchards are still contaminated with the pesticide. Arsenic compounds are still being used today as herbicides or wood preservatives.

Natural pesticides, extracts from certain plants, were often very good pesticides. Natural defenses built u by plants to certain predators were isolated then applied to other plants. Nicotine, an extract from tobacco leaves, was used as early as the 17th century. The group of insecticides called pyrethrums were harvested and refined from crysanthemums. The plant nux vomica contains strychnine, which is still used occasionally as a rodenticide. Natural pesticides are effective, but eventually were overtaken by synthetic compounds because they were hard and costly to grow the plant then isolate and extract the necessary compounds.

The 1930s and 1940s were the "Golden Age" of pesticide creation because of the advances in synthetic chemistry. Organophosphorous compounds, including DDT were developed during World War II as potential chemical warfare agents. New herbicides were developed to increase food production and in 1946 the first [chlorine-based herbicides] were available for commercial use. Included in this group are the compounds 2,4-D, 2,4,5-T not particularly toxic themselves, but when those are mixed together, produce the well-known conaminant of Agent Orange. 2,4,5-T also contains a small amount of dioxin.

Regulation of pesticide use began in 1947 when Congress passed the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) which attempted to required that pesticides be safe and effective. Not until Rachel Carson's publishing of Silent Spring, which highlighted the negative effects of many pesticides most notably DDT, did any real change occur. In 1972, the US Environmental Protection Agency was created and a pesticide registry was created and some of the most devastating compounds were outlawed.

The world is completely dependent on pesticides. In 1997, the [EPA} reported that 4.6 billion pounds of pesticides were used in the US and worldwide estimates conclude 5.7 billion pounds were used at a cost of $37 billion.

Controversy and Opinion

The economic argument for pesticides is not nearly as strong as has been presented because a

Teaching Resources

[Powerpoint Presentation on Pesticides|^chp_6_sl_pesticide.ppt]

External Links

• Pesticide Gateway
  
  
• Pesticide Information Profile
  
  
• PAN Pesticides Database
  
  
• European Union - Chemical and Pesticide Information . (accessed: 4 April 2003).
  Site contains policy and other information on the use of pesticides in agriculture.
  
• World Health Organization - WHO Pesticide Evaluation Scheme (WHOPES)\ . (accessed: 4 April 2003).
  WHOPES is an "international programme which promotes and coordinates the testing and evaluation of new pesticides proposed for public health use."
  
• International Programme on Chemical Safety (IPCS). (accessed: 4 April 2003).
  "IPSC main roles are to establish the scientific basis for safe use of chemicals, and to strengthen national capabilities and capacities for chemical safety."
  
• U.S. National Library of Medicine's (NLM) Enviro-Health Links - Pesticide Exposure . (Accessed 21 May 2006).
  
• USDA - National Agricultural Statistics Service - Agricultural Chemical Use (Accessed 16 May 2005).
  
• Ontario College of Family Physicians Pesticides Paper (accessed: 16 June 2004). An extensive review of the health effects of pesticides.
  
• Health Canada - Pesticide Information (accessed: 9 April 2003).
  
• U.S. Environmental Protection Agency (EPA) - Office of Pesticides Programs (OPP). (accessed: 19 June 2004).
  OPP's mission is "to protect public health and the environment from the risks posed by pesticides and to promote safer means of pest control."
  
• U.S. Geological Survey - National Water-Quality Assessment (NAWQA) Program (accessed: 4 April 2003).
  NAWQA provides an assessment water use in the U.S. and of pesticides in the streams, rivers, and ground water of the United States.
  
• California Department of Pesticide Regulation (accessed: 4 April 2003).
  The mission of this Department is "to protect human health and the environment by regulating pesticide sales and use, and by fostering reduced-risk pest management."
  
• En espanol (Spanish Language) - Almacenar y Desechar - Pesticidas: Regulación de Pesticidas - (Storage and Disposal of Pesticides) - U.S. Environmental Protection Agency (EPA). (accessed: 19 June 2004).
  
• Washington State University - Pesticide Education Program: education with an emphasis on personal safety, environmental protection, and effective integrated pest management. (accessed: 04 April 2006).
  
• Scorecard Information on the use of pesticides and other chemicals. Produced by the Environmental Defense Fund. (accessed: 29 August 2004).
  
• Food News Consumer information about pesticides in food. Produced by the Environmental Working Group. (accessed: 29 August 2004).
  
• Pesticide Action Network North America (PANNA). (accessed: 4 April 2003).
  "PANNA works to replace pesticide use with ecologically sound and socially just alternatives." See their recent report - "Chemical Trespass - Pesticides in our bodies and corporate responsibility"
  
• Pesticide Action Network International (PANI) (accessed: 4 April 2003).
  "PANI is a network of over 600 participating nongovernmental organizations, institutions and individuals in over 60 countries working to replace the use of hazardous pesticides with ecologically sound alternatives (English, French, Spanish)."
  
• Pesticide Database site - by Pesticide Action Network North America (PAN). (accessed: 4 April 2003). //
  "The PAN Pesticide Database brings together a diverse array of information on pesticides from many different sources, providing human toxicity (chronic and acute), ecotoxicity and regulatory information for about 5,400 pesticide active ingredients and their transformation products, as well as adjuvants and solvents used in pesticide products."
  
• National Pesticide Telecommunications Network (NPTN). (accessed: 4 April 2003).
  NPTN is based at Oregon State University and is cooperatively sponsored by the University and EPA. NPTN serves as a source of objective, science-based pesticide information on a wide range of pesticide-related topics, such as recognition and management of pesticide poisonings, safety information, health and environmental effects, referrals for investigation of pesticide incidents and emergency treatment for both humans and animals, and cleanup and disposal procedures.//
  
• Beyond Pesticides Online. (accessed: 4 April 2003).
  "Beyond Pesticides is a national network committed to pesticide safety and the adoption of alternative pest management strategies which reduce or eliminate a dependency on toxic chemicals."
  
• EXTOXNET InfoBase Online. (accessed: 4 April 2003).
  EXTOXNET provides a variety of information about pesticides, including - the Pesticide Information Profiles (PIPs) for specific information on pesticides and the Toxicology Information Briefs (TIBs) contain a discussion of certain concepts in toxicology and environmental chemistry.
  
• [Washington Toxics Coalition (WTC).] (accessed: 4 April 2003).
  WTC provides information on model pesticide-policies, alternatives to home pesticides, and much more.
  
• The Northwest Coalition for Alternatives to Pesticides (NCAP) NCAP works to protect people and the environment by advancing healthy solutions to pest problems. (accessed: 3 July 2004).
  
• Monsanto Company (accessed: 4 April 2003). Site contains information on Monsanto company pesticides and agricultural products.
  Integraed Pest Management
  
• [Integrated Pest Management (IPM)] U.S. EPA - Integrated Pest Management (IPM) | http://www.epa.gov/ebtpages/pestpestmintegratedpestmanagementip.html\]\\- Extensive information on pest management and pesticides.
  
• University of Minnesota's electronic textbook of Integrated Pest Management
  "We plan to assemble a large number of "chapters" relating to the theory and implementation of Integrated Pest Management (IPM). Our goal for this Web page is to eventually have hundreds of chapters relating to integrated pest management in the broad sense (not just insect pest management)."
  
• The Consortium for International Crop Protection (CICP), working for a quarter of a century to implement effective and environmentally-sensitive crop protection worldwide.
  
• The NSF Center for Integrated Pest Management (CIPM) - North Carolina Pest Management Information.
  {King County, Washington State, IPM program and information | http://www.govlink.org/hazwaste/interagency/ipm/index.cfm\] - excellent basic information, with section on school programs.
  
  
  

References

Gilbert, Steven G. A Small Dose of Toxicology. CRC Press, 2004.

Kamel F and Hoppin JA. Association of pesticide exposure with neurologic dysfunction and disease. Environ Health Perspect. 2004 Jun;112(9):950-8. Available online at EHPonline. (accessed: 30 June 2004).

MMWR (1999). Farm worker illness following exposure to carbofuran and other pesticides - Fresno County, California, 1998. February 19, 1999, 48(6), 113-116. (accessed: 5 July 2003).

Dean, S. R., & Meola, R. W. (2002). Effect of diet composition on weight gain, sperm transfer, and insemination in the cat flea (Siphonaptera: Pulicidae). J Med Entomol, 39(2), 370-375.

Dryden, M. W., & Gaafar, S. M. (1991). Blood consumption by the cat flea, Ctenocephalides felis (Siphonaptera: Pulicidae)

Pimentel, David, H. Acquay, M. Biltonen, P. Rice; M. Silva, J. Nelson, V. Lipner; S. Giordano, A. Horowitz, M. D'Amore. [Environmental and Economic Costs of Pesticide Use|
Environmental and Economic Costs of Pesticide Use
+]. BioScience (Vol. 42, No. 10 (Nov., 1992), pp. 750-760). Retreived on 12-6-06.