National Environmental Health Association

Pesticides have long been used throughout the world in public health programs to control human diseases transmitted by vectors or intermediate hosts as well as in agriculture for crop protection. The use of pesticides has increased dramatically in the past 50 years; for example, in 1939, there were 32 pesticide products registered with the U.S. Department of Agriculture. By 1989, however, there were 729 active-ingredient pesticide chemicals mixed with other ingredients and formulated into 22,000 commercial products (1,2). In 1995, sales of pesticides in the United States alone totaled 1.25 billion pounds of active ingredients and $10.4 billion (3).

With increased use of pesticides comes the increased risk of both pesticide misuse and pesticide poisoning. According to Grossman (4), in 1993, 140,000 pesticide exposures, 93% of which involved home use, were reported to U.S. poison control centers. Of the reported exposures, 25% involved pesticide poisoning symptoms; over half of the exposures involved children under the age of 6.

The purpose of this position paper is to review current information on the status of pesticide use and surveillance with particular emphasis on the implications for environmental and public health. It is intended to be used as a basis for initiating discussions on the topic among environmental and public health practitioners and colleagues in related fields with policy makers at all levels—local, state, national, and world-wide.

According to the United Nation’s Food and Agriculture Organization (5), a pesticide is “any substance or mixture of substances intended for preventing, destroying, or controlling any pest, including vectors of human or animal disease, unwanted species of plants or animals causing harm during, or otherwise interfering with, the production, processing, storage, transport, or marketing of food, agricultural conditions, wood and wood products, or animal feedstuffs, or which may be administrant to animals for the control of insects, arachnids, or other pest in their bodies.” According to Grossman (4), over 70 million U.S. households make more than 4 billion pesticide applications per year from a home arsenal averaging three to four pesticide products, ranging from pest strips, bait boxes, and bug bombs to flea collars, pesticidal pet shampoos, aerosols, granules, liquids, and dusts. In the United States, approximately 60-70% of pesticides used are herbicides, 25-30% are insecticides, and 10-15% are fungicides; indeed, approximately 75% of all cropland and 70% of livestock are treated with pesticides, with almost 100% of some crops (corn, soybeans, cotton) treated with herbicides (6).

Pesticides are deliberately released into the environment to produce biological effects. Unfortunately, many pesticides cause unintentional effects, including human toxicity. According to Weisenburger (6), pesticide exposure may result in both acute and chronic health effects, including acute and chronic neurotoxicity, organ and organ system damage, irritation and chemical burns, and infant methemoglobinemia. In addition, a variety of cancers, particularly hematopoietic cancers, immunologic abnormalities, and adverse reproductive and developmental effects due to pesticide exposure have been reported. Table 1 contains a listing of human health effects seen following exposure to some common pesticides. In addition, although several sources of pesticide poisoning information—such as poison control centers and emergency rooms—exist, there is no comprehensive source for this information.

Also of concern are current pesticide use and disposal practices. Leftover products from home use, spray drift from application sites, runoff from agricultural fields, accidental spills, and other practices—including inappropriate or illegal use of pesticides or pesticide formulations—have made pesticide contamination ubiquitous in the environment (7). For example, in 1996 hundreds of homes were illegally sprayed with methyl parathion, a cotton pesticide, by applicators in Mississippi, Louisiana and Alabama resulting in the temporary relocation of over 1,100 persons. With respect to disposal, fully 6% of American households simply do not dispose of pesticides because they do not know how to safely. In a study of pesticide labels, Lockwood et al., (8) found that it requires an eleventh grade cognitive level to understand a pesticide label, which means that 40-50% of the general population cannot read and understand the directions on a pesticide product label, assuming they have the 20/30 visual acuity to read the fine print. As of the late 1980's an estimated 1 million households still stored products containing chlordane; 150,000 still had stored products with DDT; 70,000 had heptachlor; and 85,000 stored Silvex, which is 2,4,5-T or the herbicide that is known to contain 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as a contaminant (3).

The general population may be exposed to pesticides in several ways, according to the route of exposure, such as inhalation, ingestion of pesticides, or absorption through the skin (via clothing or direct contact). For example, residents living in proximity to farming areas may be exposed to pesticide sprays in the air and in contaminated food or water; people in urban areas may eat crops or animal products or drink water contaminated with pesticide residues (9). For example, in 1993 USDA’s Agricultural Marketing Service found that 39% of 7,328 samples tested had two or more pesticide residues. During an average day, most of us consume trace amounts of three to five pesticides. With respect to drinking water, approximately 24 million people are exposed to herbicides, the most common contaminant nationwide in drinking water, in the Midwest and Great Lakes Region (3). Additionally, there may be exposure via air, water, and food as a result of the use of pesticides in public health programs aimed at killing disease vectors in residential areas (9). Finally, in what has been termed the “circle of poison,” pesticides manufactured in the U.S. and shipped out to other countries may return on imported fruits and vegetables.

Most pesticide formulations contain a small amount of the active ingredient, the pesticide, and a much larger amount (up to 99+%) of other substances, referred to as “inert ingredients.” Typically these substances include carrier substances or solvents and compounds that improve absorption; however, these substances are not usually included in any discussion of the effects on health, even though their adverse effects may exceed those of the active ingredients (9). The adverse effects of pesticides may also be caused by impurities, such as dioxins in certain phenoxyacid herbicides, ethylene thiourea in ethylene bisdithiocarbamates, and isomalathion in malathion (9). According to Grossman (4), the EPA estimates that there are at least 1,700 chemical compounds collectively listed under the rubric “inert ingredients” on pesticide labels. Unfortunately, inert ingredients are low priority, accounting for under 1% of the Office of Pesticide Programs budget, as the EPA still has many older (pre-1972) active ingredients that need to be reregistered and evaluated for health effects under the Federal Insecticide, Fungicide, and Rodenticide Act (4). Also according to Grossman (4), EPA has no specific procedures or timeframes for ensuring that these inert substances are reviewed, according to the EPA’s Office of the Inspector General.

Many other authors have developed recommendations that address pesticides (1-3,10,11); what follows is a listing of new, as well as a compilation of old, recommendations.

• Discontinue registration of new high-risk pesticides. (Note: High-risk pesticides are those which fall within the “supertoxic” range; that is, they have an oral LD50 of <5 mg/kg or have a dermal LD50 of <20 mg/kg.)

• Make the transition to biointensive integrated pest management (IPM) the goal of national policy by encouraging the adoption of IPM on 75% of agricultural cropland by the year 2000. (Note: According to Benbrook et al. [3] “IPM is a systems approach to pest management that is based on an understanding of pest ecology. It relies on resistant varieties and promoting plant health, crop rotation, disrupting pest production, and the management of biological processes to diversify and build populations of beneficial organisms. Reduced risk pesticides should be used only as a last resort.”)

• Require mandatory reporting of all pesticide use, not just of pesticides classified for restricted use (exclusive of typical household consumer use).

• Require mandatory reporting of occupational pesticide-related incidents and illness.

• Make the existing industrial data bases on health surveillance of pesticide-exposed workers usable to the scientific community.

• Maximize the use of routinely collected data, such as doctor’s reports for Workers’ Compensation, to supplement descriptive studies.

• Modify and use national surveys of acute health effects (including the National Center for Health Statistics hospital survey, emergency room surveys, and the American Association of Poison Control Centers poisoning survey) so that they include standardized information on occupation, race, ethnicity, income, education, and circumstances of pesticide-related incidents.

• Collect information on occupation in emergency rooms at the time of the initial visit for a specific problem.

• Encourage additional research on pesticides and their health effects. (Note: It is quite obvious there is a dire need for all types of properly-designed research---on children, seasonal workers, adults, exposure scenarios/assessments, etc.)

• Accelerate the testing of banned and restricted products that still pose a threat to humans and wildlife because of their persistence and presence in human tissue.

• Assess the quality of information on people of color in routinely collected vital and medical records, census, and other data.

• Investigate cancer and the potential neurodevelopmental and neurobehavioral effects of pesticide exposure among children of farm workers, including leukemia, lymphoma, and primary brain cancer.

• Design and carry out studies that address reproductive outcomes in male and female workers and their offspring who are exposed to pesticides.

• Investigate the association, if any, between pesticide exposure and autoimmune disorders, with emphasis on determining the role of specific classes and types of pesticides.

• Develop inexpensive, short-term screening techniques to test new and old products for endocrine, nervous, and immune system disruptive capacity.

• Expand toxicity testing in animals to include evaluation of toxicity to infant and young animals.

• Increase public awareness of inequities in exposures to pollution/act to reduce these inequities.

• Provide both the public and workers with access to relevant and understandable information on exposure to pesticides and the means of minimizing exposure through the use of work practices, protective equipment, and simple hygiene procedures, including soap and water.

• Develop more innovative methods of delivering information to the public, employers, and workers to promote the use of protective equipment and safer work practices. The language, format, and distribution of basic written information should assure that the materials are culturally relevant and appropriate. Heavy reliance on conventional written materials as the primary educational tool in populations with limited reading skills is not particularly effective. Use of standardized markings is strongly encouraged.

• Release exposure and health effects data to the public on public-use computer data tapes.

• Disseminate educational materials about resources for dealing with exposure through all communities.

• Keep the medical community better informed, so that clinicians are more alert to pesticide-related illness.

• Establish tolerances that protect children, taking into account the physiologic, developmental, and dietary differences between children and adults.

• Consider multiple pesticides that share a common mechanism of action and therefore may be additive or synergistic in their effects when determining residue tolerance levels.

• Enforce existing regulations and require additional provisions for basic levels of personal protection and washing facilities for all agricultural workers.

• Build the infrastructure necessary to promote the use of IPM in all markets.

• Promote smarter, more efficient regulation; that is, make more high-risk chemical pesticides more difficult to buy and more costly to use. In addition, federal regulations on household pesticides should encourage the use of household hazardous waste collection sites for disposal of used household pesticide containers.

• Extend the Occupational Safety and Health Act (OSHA) coverage to farm and field workers.

• Identify the specific obstacles and constraints on the EPA, the Department of Health and Human Services, and the Department of Labor (OSHA) that prevent them from conducting research, providing health services, and enforcing regulations to alleviate environmental inequities in exposure to toxic substances.

• Require industry to test all new products, their metabolites, intermediates, and byproducts for a) multigenerational immune, endocrine, reproductive, and nervous system effects in at least three animal species and b) their environmental fate in all media.

Upon adoption, the National Environmental Health Association should disseminate this paper as widely as possible by release to the membership, publication in the Journal of Environmental Health, provision of copies of this paper to affiliates to share with their members, and provision of copies of this paper to similar professional associations for their review. Affiliates and members should be encouraged to provide comments to legislators based upon the information contained herein, or by providing a copy of this document as augmentation to comments provided.

1. Moses M, Johnson ES, Anger WK, Burse VW, Horstman SW, Jackson RJ, et al. Environmental equity and pesticide exposure. Toxicol Ind Health 1993;9(5):913‑59.

2. Maroni M, Fait A. Health effects in man from long‑term exposure to pesticides. A review of the 1975‑1991 literature. Toxicol 1993;78(1‑3):1‑180.

3. Benbrook CM, Groth E, Halloran JM, Hansen MK, Marquardt S. Pest management at the crossroads. New York: Consumers Union, 1996.

4. Grossman J. What’s hiding under the sink: dangers of household pesticides. Environ Health Perspect 1995;103(6):550-4.

5. FAO International Code of Conduct on the Distribution and Use of Pesticides. Food and Agriculture Organization of the United Nations, Rome, 1986;28.

6. Weisenburger DD. Human health effects of agrichemical use. Hum Pathol 1993;24:571-6.

7. Wolfe MF, Seiber JN. Environmental activation of pesticides. Occup Med 1993;8(3):561‑73.

8. Lockwood JA, Wangberg JK, Ferrell MA, Hollon JD. Pesticide labels: proven protection or superficial safety?. J Am Optometric Assoc 1994;65(1):18‑26.

9. Al-Saleh IA. Pesticides: a review article. J Environ Pathol Toxicol Oncol 1994;13(3):151-61.

11. Colborn T. Pesticides—how research has succeeded and failed to translate science into policy: endocrinological effects on wildlife. Environ Health Perspect 1995;103(Suppl 6):81-6.

12. Extoxnet. Extension Toxicology Network. 1993. Http://ace.ace.orst.edu/info/extoxnet/

13. Foster WG. The reproductive toxicology of Great Lakes contaminants. Environ Health Perspect 1995;103(9):63-9.

14. Vial T, Nicolas B, Descotes J. Clinical immunotoxicity of pesticides. J Toxicol Environ Health 1996;48:215-29.

15. Lu FC. A review of the acceptable daily intakes of pesticides assessed by WHO. Reg Toxicol Pharmacol 1995;21:352-64.

16. Fleming LE, Timmeny W. Aplastic anemia and pesticides—an etiologic association? JOM 1993;35(11):1106-16.

17. Murphy SD. Toxic effects of pesticides. In: Klassen CD, Amdur MO, Doull J, eds. The basic science of poisons. Casarett and Doull’s Toxicology, New York: Macmillan, 1986:519-81.

18. Sittig M. Handbook of toxic and hazardous chemicals and carcinogens. Park Ridge, NJ: Noyes Publications, 1985.

19. Arena JM, Drew RH, eds. Poisoning: toxicology, symptoms, treatments. Springfield, IL: Charles C. Thomas, Publisher, 1986.

(Original paper prepared by Ginger L. Gist, Ph.D., DAAS, Senior Environmental Health Scientist, Agency for Toxic Substances and Disease Registry)

The committee foresees the only fiscal impact on NEHA with the adoption of this paper to be the cost of making and mailing copies. The fiscal impact of the problem will be felt mainly by state and federal authorities with responsibilities in pesticide regulation.

Table 1.—Health effects of selected pesticides (1,12-19).

Pesticide	Evidence of Health Effects		Produces Malformations in Pregnancy	Alters Fertility	Potentially Immunotoxic	Potential Endocrine Disrupter
	Known	Suspected
2,4-D	Chloracne (TCDD)	Cancers: soft-tissue sarcoma, lymphatic and hematopoietic, stomach, colon, prostate; liver dysfunction; teratogenesis	Yes		Yes	Yes
2,4,5-T	Chloracne; porphyria	Cancers: soft-tissue sarcoma, lymphatic and hematopoietic, stomach, colon, prostate; liver dysfunction; teratogenesis	Yes			Yes
Aldrin	Neurotoxic effects	Cancer	Yes	Yes		Yes
Arsenicals	Lung cancer; liver disease; pancytopenia; arsenical keratoses; peripheral neuropathy	Aplastic anemia
Captan		Cancer	Possibly	Yes
Carbaryl	Neurotoxic effects	Chromosome aberrations; cancer; kidney damage	Yes	Possibly	Yes	Yes
Chlordane/ Heptachlor	Neurotoxic effects; liver damage; kidney damage	Myelolymphoproliferative disorders; brain cancer; liver cancer		Yes	Possibly	Yes
Chlordecone (Kepone)	Neurotoxic effects	Liver disease; liver cancer		Yes		Yes
Diazinon	Neurotoxic effects		Yes
Dibromo- chloropropane	Cancer; liver disease; kidney failure			Yes		Yes
Dichlorvos	Neurotoxic effects	Cancer; lung damage; liver damage	Possibly	Possibly	Yes
DDT	Chloracne; cerebral dysfunction; liver damage; kidney damage	Chromosome aberrations; high cholesterol and triglyceride levels; tremors, muscular weakness; pancreatic cancer; aplastic anemia; thyroid damage		Yes	Yes	Yes
Dieldrin	Neurotoxic effects	Cancer	Yes	Yes	Yes	Yes
Diquat dibromide	Corrosive; gastrointestinal tract damage; kidney damage; liver damage; neurotoxic effects; cataracts			Possibly	Yes
Endrin	CNS depression		Yes		Yes
Ethylene dibromide	CNS depression; severe eye and skin irritation; cancer; lung damage		Possibly	Yes
Hexachloro- benzene	Porphyria	Liver cancer; thyroid cancer; neurotoxic effects; lung damage	Yes	Possibly	Yes
Lindane	Aplastic anemia; heart damage; neurotoxic effects	Liver cancer; liver damage; leukemia; kidney damage		Yes	Yes	Yes
Maneb	Hemolytic anemia; kidney damage; irritant; heart damage	Cancer; thyroid hyperplasia	Yes	Yes	Yes	Yes
Methyl parathion	Neurotoxic effects	Liver damage; inflammation of the stomach; respiratory stress	Yes	Possibly	Yes
Mirex		Liver cancer		Yes	Yes	Yes
Paraquat	Lung damage; kidney failure; liver damage; skin, eye, and mucosal irritant; damage to the heart, adrenal glands, and digestive system	Parkinson’s disease; cancer	Yes	Possibly	Yes
Pentachloro- phenol	Liver damage; kidney damage; neurotoxicity; chloracne	Aplastic anemia; cancer	Possibly	Possibly	Yes	Yes

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