Pesticides, including herbicides, insecticides, and other pest control chemicals, can cause a variety of short-term (acute) and long-term (chronic) health effects. Possible acute symptoms of exposure include headache, nausea, diarrhea, dizziness, skin irritation, and respiratory irritation.¹ Many acute symptoms can appear similar to those of common illnesses, such as the "flu," often resulting in misdiagnosis. 

Scientific studies link certain pesticides to cancer, birth defects, nervous system disorders, reproductive problems, endocrine (hormone) disruption, and immune deficiency. Cancer rates in the United States, including childhood cancer, have increased in the last 30 years, and many scientists and researchers attribute part of the increase to pollution in the environment, including pesticides.² Certain classes of insecticides have known effects on the nervous system, specifically on children.³ An increasing amount of evidence shows that certain chemicals, including many pesticides, can mimic or block the action of naturally occurring hormones in the body, resulting in reproductive problems and birth defects in wildlife, as well as declining sperm counts, increasing cancer rates, and birth defects in humans.⁴ These chronic effects can take many years to appear, making it difficult to connect them to past exposures.

Asthma

Asthma is at epidemic levels in the United States, and is now the most common chronic disease among children. According to the American Lung Association, "close to 6.3 million children under 18 currently have asthma," (based on the 2001 National Health Interview Survey) with an estimated 131,704 children in Washington state suffering from pediatric asthma.⁵

Vital new research on the environmental causes of asthma is just now being done. For example, a new survey assessing childhood asthma concluded that "exposures to herbicides, pesticides, and the farm environment in the first year of life may increase the risk for early onset persistent asthma, a subtype of asthma associated with long-term morbidity."⁶ The authors found that "children exposed to any pesticide or herbicide in the first year of life were at 2.53 times higher risk of asthma compared to children who were never exposed to either." These significant findings, among many others, open the door for much more exploration into the contributions of pesticide exposure to rapidly rising asthma rates in our children.

Some insects, such as cockroaches, can also exacerbate asthma, but in trying to solve these problems, we must avoid introducing chemicals that can also play a role in asthma.

Learning Disabilities

It is estimated that 5% to 10% of children in public schools in the United States are living with some type of learning disability.⁷ Research has shown that some types of pesticides, particularly organophosphate insecticides, have serious impacts on the developing brain and nervous system, particularly from exposure during the latter stages of pregnancy.³ The pesticide chlorpyrifos was recently cancelled by the U.S. government for many uses due to concern over its impacts to children's nervous system development, among other things, but many similar-acting chemicals remain on the market. Studies conducted by Dr. Elizabeth Guillette in the Yaqui Valley of Mexico found significant neurodevelopmental impacts on children who had high pesticide exposures compared with a control group.⁷ 

Much more research needs to be done to fully understand the links between pesticide exposures and their impacts on the development of the nervous system. As physician Ted Schettler wrote, "neurodevelopmental data are lacking for the large majority of known or suspected neurotoxicants. Regulatory agencies have generally failed to require neurodevelopmental testing of chemicals before they are marketed."⁸ He added that "residual uncertainties, however, can not be an excuse for avoiding precautionary action when available evidence establishes the plausibility of harm."

Exposure Rates

The risk of harm from pesticides depends on the amount of exposure and the individual's susceptibility, in addition to the inherent toxicity of the material. Since children's bodies are still developing, they are more susceptible to the risks from pesticide exposure. At the same time, their exposures are greater. Children have more skin surface and breathe more air than adults relative to their body weight, meaning their exposure to pesticides can be much higher. Contact with lawns and playgrounds can also lead to increased exposure. The tendency of kids to put their hands and objects into their mouth dramatically increases the risk of exposure to pesticide residue. 

Children are also exposed to pesticide residues found indoors, particularly in carpets. Studies have found that pesticide residues detected indoors are not exclusively from applications made inside. Rather, pesticides can be tracked in from applications made out of doors or elsewhere. A study conducted on the lawn-application pesticides 2,4-D and dicamba - chemicals used by many school districts in our Washington survey - found they were easily tracked indoors, and use on lawns leads to exposure significantly higher than pre-application levels.⁹

Many of these health concerns have been discovered long after pesticides were allowed for use, since risk assessments conducted for pesticide registration by the federal government have assumed health impacts from pesticide exposure on adults, not on small children. Because there are significantly fewer studies on the impacts of exposure to children, and children's size and vulnerability to exposure are not taken into full account in pesticide registration, it is likely that we will continue to discover new health impacts as pesticides are used around children.

References

1. J.R. Reigart, and J.R. Roberts. Recognition and Management of Pesticide Poisonings (Washington, D.C.: Environmental Protection Agency, 1999).
2. J.L. Daniels, A.F. Olshan, and D.A. Savitz, "Pesticides and Childhood Cancers." Environmental Health Perspectives 105, 10 (1997): 1068-1077.
3. T. Schettler, et al. In Harm's Way: Toxic Threats to Child Development (Boston, Mass.: Greater Boston Physicians for Social Responsibility, 2000).
4. T. Colburn, F.S. vom Saal, and A.M. Soto, "Developmental Effects of Endocrine-Disrupting Chemicals in Wildlife and Humans." Environmental Health Perspectives 101, 5(1993): 378-384.
5. American Lung Association, "Estimated Prevalence and Incidence of Lung Disease by Lung Association Territory." Epidemiology and Statistic Unit, Research and Scientific Affairs, September 2003.
6. Salam, M., et al., "Early Life Environmental Risk Factors for Asthma: Findings from the Children's Health Study." Environmental Health Perspectives Online (In-Press), 9 Dec. 2003.
7. Guilette, E., et al. "An anthropological approach to the evaluation of preschool children exposed to pesticides in Mexico." Environmental Health Perspectives 106: 347-353. 1998.
8. Schettler, Ted. "Toxic Threats to Neurologic Development of Children." Environmental Health Perspectives 106(sup. 6) (2001).
9. Nishioka, M., et al., "Distribution of 2,4-D in Air and on Surfaces inside Residences after Lawn Applications: Comparing Exposure Estimates from Various Media for Young Children." Environmental Health Perspectives 109(11) (2001).