Angeles area, many immigrant poor may be fishing in contaminated waters to supplement their source of protein.

The combined effect of poorer health status and of likely higher exposure to environmental toxicants suggests that the further burden of pesticide exposure could lead to toxic effects at levels that do not produce effects in other children. Therefore one might expect that adverse effects of pesticides, whether acute or chronic, might be magnified in this subpopulation.

Age-Dependent Toxicity

Traditional risk assessment methods generally do not make specific allowances for any unique features of infants and children. Species conversion of dietary intakes per unit of body weight are normally based on adult body weights and food consumption data (McColl, 1989).

Infants and children are unique in a number of ways (see Chapters 2 and 3). Babich and Davis (1981) noted that children may be hypersusceptible to food toxicants, especially heavy metals and pesticides. The realization that the process of atherosclerosis begins in childhood has led to recommendations that total fat intake of children over 2 years of age not exceed 30% of calories and that cholesterol intake not exceed 300 mg daily (American Health Foundation, 1989). Gaines and Linder (1986) estimated the LD50s for 57 pesticides in adult and weanling rats and found four cases (leptophos, methidathion, pyrazon, and sulfoxide) in which the weanlings were more sensitive than the adults several in which they were less sensitive.

Infants and children may be more or less susceptible to exposure to toxic chemicals than adults (see Chapters 2 and 3). Drugs such as amikacin and the aminoglycosides are less toxic to children than adults, whereas children seem to be more sensitive to salicylates than adults (Mendelson and Grisolia, 1975; Brown et al., 1982; Faden et al., 1982). Comparative analyses of the acute lethality of drugs (Goldenthal, 1971), chemotherapeutic agents (Glaubiger et al., 1982), insecticides acting through cholinesterase inhibition (Brodeur and DuBois, 1963), and pesticides (Gaines and Linder, 1986) indicate that infants and children may exhibit a higher or lower LD50 than adults.

Collectively, these data provide information on the magnitude of the effects of age on susceptibility to toxic chemicals. Specifically, Brodeur and Dubois (1963) observed that the LD50s for adult rats were 2 to 4 times greater than the corresponding LD50s for weanling rats for 15 of 16 insecticides examined.

Potential carcinogenic risks may depend on the unique physiological sensitivities of infants and children as well as the specific age at which



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement