The Unique Vulnerability of Infants and Children to Pesticides

Philip J. Landrigan, et al EHP v.107, Supp.3 Jun99

In addition to being proportionately more heavily exposed to pesticides than adults, infants and children are biologically more vulnerable to them. The NAS report, "Pesticides in the Diets of Infants and Children" (1), identified three biological bases for that vulnerability.

First, children's metabolic pathways, especially in the first months after birth, are immature compared to those of adults. In some instances, children are actually better able than adults to cope with environmental toxicants. They are unable, for example, to metabolize toxicants to their active form (34). More commonly, however, fetuses, infants, and children are less able to detoxify chemicals such as organophosphate pesticides and thus are more vulnerable to them (30,35,36).

Second, infants and children are growing and developing, and their delicate developmental processes are easily disrupted. Their immune system is immature. Many organ systems in infants and children undergo extensive growth and development throughout the prenatal period and the first months and years of extrauterine life. Thus, if cells in an infant's brain are destroyed by pesticides, if reproductive development is diverted by endocrine disrupters, or if development of the immune system is altered, the resulting dysfunction can be permanent and irreversible. Some of the biologic mechanisms responsible for these developmental vulnerabilities are discussed in detail in an accompanying report by Eskenazi et al. (37).

Third, because children have more future years of life than most adults, they have more time in which to develop chronic disease that may be initiated by early exposures. Exposures sustained early in life, including prenatal exposures, appear more likely to lead to disease than similar exposures encountered later. Also, deficits sustained early may persist lifelong (1). There is evidence, for example, that pre- and postnatal exposures to pesticides increase risk of childhood cancer (38), and concern has arisen that early exposure to neurotoxic pesticides may increase risk in later life of chronic neurologic diseases such as dementia, Parkinson's disease, and amyotropic lateral sclerosis (39 40).

Recent findings on the developmental toxicity of two pesticides commonly used in the inner-city environment, chlorpyrifos and certain pyrethroids, exemplify the special susceptibilities of infants and children. These data underscore the potential risks to children's health and development of exposures to these agents in early life.