excerpted from Failing Health, Pesticide Use in California Schools, by the California Public Interest Research Group Charitable Trust

Children are Less Tolerant to Toxic Chemicals

Children are not simply little adults. Early developmental stages of their organs, nervous systems, and immune systems, greater rates of cell division, and their lower body weight increase their susceptibility to pesticide exposure. Immature organs and other developing biological systems are particularly vulnerable to toxic contaminants. Furthermore, pesticides may become more concentrated in the fatty tissues of young children because their fat as a percentage of total body weight is lower than for adults.

A 1993 report by the National Research Council of the National Academy of Sciences has shown that children are more susceptible than adults to the health effects from low-level exposures to pesticides over the long-term .Animal studies also suggest that the young are more susceptible to the effects of toxic chemicals. A review of 269 drugs and toxic substances, including a number of pesticides, found that the lethal dose was lower in newborn rodents than in adult rodents in 86% of the cases.

Children Receive Relatively Greater Exposure

In addition to being more vulnerable to pesticide toxicity, children’s behavior and physiology make them more likely to receive greater pesticide exposures, relative to adults. For example, significant exposure to pesticides occurs through the skin – the largest organ in the human body – and children have much more skin surface for their size than adults.Similarly, children have a higher respiratory rate, enabling them to inhale airborne pesticides at a rate faster than adults.Children’s increased contact with floors, lawns and playgrounds also increases exposure. Very young children who put fingers and other objects in their mouths may face even greater exposure. Finally, the breathing zone for children is usually closer to the floor where pesticides are re-suspended into the air after floor surfaces are disturbed.

Children are Exposed to Pesticide Residues in Dust and Carpets

Although pesticides contaminate air, soil, food, water and surfaces, studies designed to examine children’s exposure to pesticides indicate that the largest number of chemicals and the highest concentrations are often found in household dust.

Carpets act as long-term reservoirs for pesticides that are sprayed indoors.A study assessing pesticide exposure from carpet dust in homes found that the average number of pesticides found in the carpet dust samples was 12, compared to 7.5 in air samples collected in the same residences. Moreover, in all residences sampled, 13 pesticides were found in carpet dust that were not detected in the air. Diazinon, a neurotoxic insecticide, was detected in nine of 11 carpets tested.Exposure may be further exacerbated when carpets are cleaned, allowing pesticides to become airborne again and available for inhalation.

Not all of the residues in dust stem from the indoor use of pesticides. One study showed residues of 2,4-D and dicamba can be tracked in from outside on shoes. Even areas which were not treated, including lawn area and carpets, showed levels of 2,4-D after the spraying – most likely the result of spray drift during application. Researchers estimated that residues of 2,4-D can persist in household carpet dust for as long as one year.

Children are Exposed to Pesticides through Ventilation Systems

A building’s ventilation system may also contribute to greater pesticide exposure. Some pesticides can become airborne and spread throughout heat and air conditioning systems, potentially causing a repeating source of exposure.

In 1994, the insecticide propoxur was evidently distributed through a California school via the building’s air conditioning system. A teacher’s aide entered the building immediately after application and became ill with nausea, headache, nose and eye irritation and breathing difficulty.

1. Wargo, J., Our Children’s Toxic Legacy: How Science and Law Fail to Protect Us From Pesticides, Yale University Press, New Haven, CT 1996.

2. National Research Council, Pesticides in the Diets of Infants and Children, National Academy Press, Washington, DC, 1993.

3. Wyatt, R., “Intolerable Risk: The Physiological Susceptibility of Children to Pesticides,” Journal of Pesticide Reform, Fall 1989.

4. Mott, L., Our Children at Risk: The Five Worst Environmental Threats to Their Health, Natural Resources Defense Council, November 1997, p. 5 citing Principles for Evaluating Health Risks from Chemicals during Infancy and Early Childhood. (no author or date provided), p. 56.

5. Mott, L., op. cit.

6. U.S. Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances, Questions and Answers: Chlorpyrifos, February 1997.

7. Schettler, T., Generations at Risk: How Environmental Toxins May Affect Reproductive Health in Massachusetts, Greater Boston Physicians for Social Responsibility and MASSPIRG, Boston, MA 1996, p. 51, citing Whitmore, R. et al., “Non-occupational exposures to pesticides for residents of two U.S. cities,” Archives of Environmental Contamination and Toxicology, Vol. 26, pp. 1-13, 1993. See also, Roberts, W. et al., “Development and Field Testing of a High Volume Sampler for Pesticides and Toxics in Dust,” Journal of Exposure Analysis and Environmental Epidemiology, Vol. 1, No. 2, 1991.

8. Simcox, N., et al., “Pesticides in Household Dust and Soil Exposure Pathways for Children of Agricultural Families”, Environmental Health Perspectives, Vol. 103, No. 12, December 1995, pp. 1126-1134.

9. Whitmore, R. W., et al., Non-Occupational Exposure to Pesticides, Archives of Environmental Contamination and Toxicology, Vol. 26, 1994, pp. 47-59.

10. Esteban, E., et al., “Association Between Indoor Residential Contamination with Methyl Parathion and Urinary Para-Nitrophenol”, Journal of Exposure Analysis and Environmental Epidemiology, 1996, p. 384.

11. Nishioka, M. et al., “Measuring Transport of Lawn-Applied Herbicide Acids from Turf to Home, Correlation of Dislodgeable 2,4-D Turf Residues with Carpet Dust and Carpet Surface Residues,” Environmental Science and Technology, Vol. 30, No. 11, 1996.

12. Mehler, L., Case Reports Received by the California Pesticide Illness Surveillance Program in Which Health Effects were Attributed to Pesticide Exposure Identified by the Word “School” in the Narrative Summary or by SIC Code 8211 and Including all Cases that Reference Cases so Identified: 1992-1994, California Environmental Protection Agency, Department of Pesticide Regulation, November 14, 1997. DPR staff would not disclose the name of the school.