Exposure Science Digest

Journal of Exposure Science and Environmental Epidemiology doi:10.1038/jes.2011.1; published online 12 January 2011

Protecting Children From Pesticides and Other Toxic Chemicals

Philip J Landrigana and Lynn R Goldmanb

  1. aDepartment of Preventive Medicine, Mount Sinai School of Medicine, New York, New York, USA
  2. bSchool of Public Health and Health Services, George Washington University, Washington, DC, USA

Correspondence: Philip J. Landrigan, phil.landrigan@mssm.edu

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Abstract

A key 1990s breakthrough in exposure science was the first recognition by policy makers of the unique exposures and exquisite vulnerabilities of fetuses, infants, and children to pesticides and other toxic chemicals. The result was legislation and other actions that significantly improved protections for children against environmental hazards.

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BACKGROUND

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Pesticides in the Diets of Infants and Children, a report issued by the National Academy of Sciences in 1993, outlined four principles that characterize children's vulnerability:

Children have greater exposures to toxic chemicals on a body-weight basis than that of adults. As compared with an adult, a 6-month-old formula-fed infant drinks seven times more water. Children have three to four times more caloric intake. Moreover, children have unique food preferences; for example, an average 1-year-old drinks 21 times more apple juice and 11 times more grape juice than an adult does. The air intake per pound of a resting infant is two times greater than that of an adult. The consequence is that children have proportionately greater intake of toxic chemicals in water, food, and air. Children's hand-to-mouth behavior and their play close to the ground further magnify their exposures.

Children's metabolic pathways are immature. Children's ability to metabolize and excrete toxic chemicals is different from adults’. In some instances, infants are at lower risk because they cannot convert chemicals to their toxicologically active forms. More commonly, however, they are more vulnerable.

Children are undergoing rapid growth and development. Research in pediatrics has identified “windows of vulnerability,” i.e., critical stages in early development when toxic exposures can cause devastating injury. Examples include phocomelia (from thalidomide), vaginal adenocarcinoma (from diethylstilbestrol), and brain injury (from methylmercury). More recently, prenatal exposures to certain endocrine-disrupting chemicals have been shown to produce profound effects on the developing brain at very low doses. These windows of susceptibility exist only in early development. They have no counterpart in adult life.

Children have more time than adults to develop chronic diseases that may be triggered by harmful exposures in the environment. Many diseases triggered by toxic chemicals are now understood to evolve through multistage, multiyear processes. Because children have more future years of life, they are at greater risk of developing disease resulting from early exposures.

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IMPACT AND IMPLICATIONS FOR EXPOSURE SCIENCE

The core insights and recommendations of the NAS report were incorporated into the 1996 Food Quality Protection Act (FQPA), the federal pesticide law. It was the first national environmental statute to contain explicit provisions for protecting children.

In the regulatory arena, the FQPA forced reexamination of pesticide standards (“tolerances”). It reduced agricultural use of organophosphates. It also led to bans on residential applications of two very widely used organophosphate insecticides: chlorpyrifos and diazinon. These bans were triggered by recognition of the compounds’ neurodevelopmental toxicity and documentation of their long residence time in indoor environments.

The FQPA changed risk assessment. It forced development of child-protective approaches that explicitly consider children's exposures and susceptibilities. It also requires the use of child-protective safety factors. It was the first legislation to mandate realistic consideration of exposures to multiple pesticides via multiple routes, including diet and drinking water, in order to assess potentially synergistic effects. In addition, it mandates consideration of exposures to chemicals that impact the endocrine system. The challenge before the US Environmental Protection Agency (EPA) today is to use these approaches rigorously and frequently.

The FQPA enabled the EPA to mandate a new assay that permits accurate assessment of the toxicity of carbamate pesticides such as aldicarb, a potent insecticide used in agriculture since 1970. With this test, the concentration of aldicarb legally allowed in food was found to be 1.2 times greater than the adult limit for acute toxicity and 3.2 times higher than the limit for acute toxicity in children. When drinking-water exposures were considered, the legally permitted levels were found to be 5 times the adult toxicity limit and 16 times the pediatric limit (EPA, 2010). The result was that the EPA announced a phaseout of aldicarb in 2010, a significant benefit for the health of all Americans, especially for children.

The recognition of children's exposures and susceptibilities embodied in the FQPA has had consequences that extend beyond pesticide regulation. It led to establishment of the Office of Children's Health Protection within the EPA. It catalyzed a Presidential Executive Order requiring agencies of the federal government to consider children's special exposures and susceptibilities in all policy and rule making (Clinton, 1997). It stimulated creation of a White House Task Force on Children's Health and Safety, and it led to passage in 2002 of the Best Pharmaceuticals for Children Act, which requires that drugs labeled for use in children undergo scientific studies to specifically examine children's susceptibilities.

Recognition of children's susceptibility has stimulated substantial increases in research in exposure science and children's environmental health. These initiatives include:

  • A national network of federally funded Centers for Children's Environmental Health and Disease Prevention Research and a global network of Pediatric Environmental Health Specialty Units (Spivey, 2007; Wilborne-Davis et al., 2007)
  • Fellowship training programs in environmental pediatrics in leading medical institutions (Landrigan et al., 2007)
  • The National Children's Study, a prospective epidemiologic study that will follow a nationally representative sample of 100,000 children from early pregnancy to age 21 to assess environmental influences on health and development (Landrigan et al., 2006)

These new initiatives may be expected to increase still further our knowledge of children's unique susceptibilities to toxic chemicals in the environment and thus to guide the future of risk assessment and exposure science.

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References

  1. Clinton W.J. Presidential Executive Order 13045: Protection of Children from Environmental Health Risks and Safety Risks, 21 April, 1997: http://yosemite.epa.gov/ochp/ochpweb.nsf/
    content/whatwe_executiv.htm
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  2. EPA. US Environmental Protection Agency Office of Chemical Safety and Pollution Prevention. Aldicarb: Revised Acute Probabilistic Aggregate Dietary (Food and Drinking Water) Exposure and Risk Assessment Incorporating Revised FQPA Factor. Washington, DC, 4 August, 2010.
  3. Landrigan P.J., Trasande L., Thorpe L.E., Gwynn C., Lioy P.J., and D’Alton M.E., et al. The National Children's Study: a 21-year prospective study of 100,000 American children. Pediatrics 2006: 118: 2173–2186. | Article | PubMed | ISI
  4. Landrigan P.J., Woolf A.D., Gitterman B., Lanphear B., Forman J., and Karr C., et al. The ambulatory pediatric association fellowship in pediatric environmental health: a 5-year assessment. Environ Health Perspect 2007: 115: 1383–1387. | PubMed | ISI |
  5. National Research Council. Pesticides in the Diets of Infants and Children. Washington, DC: National Academy Press, 1993.
  6. Spivey A. Children's health centers: past, present, and future. Environ Health Perspect 2007: 115: A192–A194. | Article | PubMed | ISI
  7. Wilborne-Davis P., Kirkland K.H., and Mulloy K.B. A model for physician education and consultation in pediatric environmental health—the Pediatric Environmental Health Specialty Units (PEHSU) program. Pediatr Clin North Am 2007: 54: 1–13, vii. | Article | PubMed | ISI