Pesticide Exposure and Health Effects

Many pesticides that have been banned or whose use has been severely restricted in industriidixed countries are still marketed and used in developing countries. These chemicals pose serious risks to the health of millions of farmers and ike environment. 

50% of all pesticide related illness and 72.5% of recorded fatal pesticide poisonings occur in developing countries, although these countries account for only 25% of the pesticides used world-wide. 

Chemical Pesticide Markets, Health Risks and Residues 

Some anecdotal accounts are included in the following examples of pesticide poisonings in order to supplement the comparatively scarce number of studies and official records and to cover as many countries as possible for some countries, anecdotal accounts were the only source of information that could be found. 

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In order to assess the potential extent of human exposures and health effects, members of dairy farm families who consumed raw dairy products known to be contaminated with heptachlor epoxide were studied (Stehr-Green et al. 1986). These individuals and an unexposed urban reference population were compared with regard to serum pesticide levels and liver toxicity. The farm family members had significantly higher mean serum levels of heptachlor epoxide (0.81 0.94 ppb), oxychlordane (0.70 0.75 ppb), and transnonachlor (0.79 0.60 ppb) than the unexposed population. This study is limited because exposure level, duration, and frequency of exposure are not known. There was no increase in prevalence of abnormal liver function tests in the dairy farm families... 

New Research. Regarding new research, the Department of Labor and the Environmental Protection Agency plan to co-sponsor a five-year study of the effects of pesticide exposure on the health of youths under sixteen years of age who are employed in agricultural operations. The study will be undertaken to determine a) actual pesticide exposure and physical effects of such exposure b) absorption rates of pesticides into the body, and c) acute and chronic health effects in relation to duration and level of exposure. 

Thoroughly referenced from a wide variety of sources, this book contains information on industrial solvents, pesticides, metals, air pollutants, and toxic gases and drugs, as well as other substances. The information presented for each chemical substance is concise yet thorough and does not require advanced training to comprehend. For each chemical, the author provides the CAS number, lUPAC name, molecular formula, synonyms, uses and exposures, toxicity and health effects, the exposure limits, and methods of proper storage and disposal. Tables and appendices are included where appropriate. 

The potential for human and environmental exposure to a pesticide product usually increases in a stepwise fashion as the product proceeds from discovery to commercial use. As pesticide exposure increases, so does the risk of adverse human health or environmental effects. Therefore, EPA s pesticide regulations are phased in as pesticide exposure, and potential risks, increase (Figure 1). 

Comparisons of farmers with long-term exposure to pesticides in rice production with farmers with no history of exposure showed that the magnitude of chronic health effects and health costs are directly related to pesticide exposure and that the net benefits of insecticide use aie negative. 

Over the last decades, several hundreds of pesticides have been marketed for intensive farming and domestic use. The widespread use of these compounds has resulted in contamination of environmental compartments, such as surface water, groundwater, soil, and air (Tariq et al. 2004 Femandez-Alvarez et al. 2008 Xue et al. 2005 Hamer et al. 2005). Studies focussing on the assessment of pesticide exposure and on the adverse effects of pesticides on both human health and the environment are a matter of a growing scientific and pubhc concern (Dorr et al. 2007 Ritter et al. 2006). 

Feller LJ and Griffin TG. 1988. Permethrin Exposure. EPA Environmental Chemistry Review Section Non-Dietary Exposure Branch Health Effects Division. Washington, DC US EPA Office of Pesticides and Toxic Substance. 

Hazard identification, step one, means identification of new chemicals or other factors that may cause harmful health effects. Previously, novel hazards were usually observed in case studies or after accidents or other excessive exposures, usually in occupational environments. Today, thorough toxicity studies are required on all pesticides, food additives, and drugs. New chemicals also have to be studied for their potential toxic effects. Thus, earlier hazards were in most cases identified after they had caused harmful effects in humans. Today, most chemical products have been evaluated for their toxicity with experimental animals. Therefore, hazard identification has become a preventive procedure based on safety studies conducted before a chemical compound or product reaches the market, and before individuals are exposed to it. ... 

Figure 3-5 graphically depicts the information that currently exists on the health effects of methyl parathion in humans and animals by various routes of exposure. The available literature reviewed concerning the health effects of methyl parathion in humans described case reports of longer-term studies of pesticide workers and case reports of accidental or intentional ingestion of methyl parathion. The occupational exposure is believed to be via the dermal and inhalation routes. The information on human exposure is limited in that the possibility of concurrent exposure to other pesticides or other toxic substances cannot be quantified. 

Children s Susceptibility. The information on health effects of endosulfan in humans is derived mainly from cases of accidental or intentional exposure of adults to high amounts of the pesticide, and the main adverse effect is neurotoxicity. No reports of adverse effects in endosulfan-exposed children were found, but it is reasonable to assume that children will exhibit similar signs and symptoms to those in adults under similar exposure conditions. Some studies in animals have provided evidence that young animals respond to endosulfan differently than adult animals (Kiran and Varma 1988 Lakshmana and Raju 1994 Sinha et al. 1995,1997 Zaidi et al. 1985), but there is no conclusive evidence to suggest that young animals are more susceptible than older ones. Further studies that evaluate a number of different end points in young as well as older organisms would provide valuable information. 

There is a significant amount of data from other countries on the effects on human health of large-scale pesticide production and use, in particular of OPPs and OCPs. Even one-time, accidental contact with some OCPs and OPPs such as dieldrin, malathion, and parathion, can lead to changes in the encephalogram (which remain for a year after exposure), disruptions of sleep patterns and memory, loss of libido, and difficulties in concentration [3]. Global practice shows that all pesticides are toxic to humans. 

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