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Risk further documented children's greater susceptibility to the effects of certain carcinogenic and neurotoxic substances due to the immaturities in their developing systems. NRDC estimated that as many as 5,500 to 6,200 of the nation's preschoolers may develop cancer sometime during their lives solely as a result of preschooler exposure to eight pesticides or metabolites at levels commonly found in fruits and vegetables. In addition, NRDC predicted that at least 3 million of today's preschool children
may be receiving exposures to neurotoxic insecticides at levels
above those the federal government considers safe.
The greater exposure of children to toxic substances is further exemplified by current widespread exposures to lead and other heavy metals. The 1.8. Department of Health and Human Services recently estimated that despite dramatic reductions in lead in certain environmental media, notably air, 17% of
metropolitan children are being exposed to harmful lead levels. 18
Although many poor, inner-city children are at high risk, the problem affects large numbers of more affluent children as well. The largest single source of this exposure is peculiar to children alone: young children ingest lead in chipping interior paint, which is found in an estimated 21 million homes nationwide." As a result of their potential exposure to lead in paint alone, an estimated 12 million young children could suffer
18 Agency for Toxic substances and disease Registry, The Nature and Extent of Lead Poisoning in children in the united states: Report to congress (July 1988). 19 Ibid.
diminished intellectual capacity, behavioral problems and a variety of other serious mental deficiencies. 20 In addition, prenatal exposures to low levels of lead, primarily through contamination of drinking water, could endanger the normal development of over 400,000 fetuses each year. 21
Major changes affecting the global environment, such as stratospheric ozone depletion, may also disproportionately affect children. For instance, the young ar. ilkely to be at greater risk of developing skin cancers later in life from increased exposure during childhood to radiation penetrating the thinning ozone layer.22 The impacts of global warming will also disproportionately aftect the children of today and their children but for a differant reason: the worst effects are expected to be felt after the turn of the century. .
Children are at greater risk from the harmful effects of ambient pollutants both because they receive greater exposures to many environmental contaminants and also because physiological Inmaturities in their developing system can render than especially susceptible to the toxic effects of this exposure. Children receive greater exposure to ambient pollutants simply
22 Basal cell and squamous cell carcinoma of the skin and malignant melanoma have all been associated with excessive sun exposure with exposures during childhood and adolescence of particular concern. willian, M.L. and R.W. Sagabiol, X.D., isunburns, Melanoma, and the Pediatrician, commentaries, Pediatrics, 84:381-382 (1989).
because proportionate to their size they eat more food, breathe more air, and drink more water.
The young, for example, have twice the caloric needs of
children also ingest more drinking water. Infants (<1 year)
The young also have higher breathing rates. Approximately twice as much air passes through the lungs of a resting infant compared to a resting adult.” As a result, twice as much of any chemical in the atmosphere reaches the lungs of the infant. Children are also much more active than adults,
23 Beheman, R.E., M.D. and v.C. Baugham, III, M.D., Nelson Textbook of Pediatrics, 12th Edition, W.B. Saunders, co., 1983.
24 NRDC, Intolerable Bisk, supra, note 17.
National Academy of Sciences, Regulating Pesticides in Foodi The Delaney Paradox, Appendix B, Washington, D.C. 1987.
25 Saunders, s., Briefing Paper on the Tolerance Assessment System For Presentation to the FIFRA Science Advisory Panel, EPA, office of pesticide Programs, p. 32 (February 1987).
26 Ershow, A.G. and K.P. Cantor, Total Water and tapwater Intake In the United States: Population-Based Estimates of quantities and Sources, National Cancer Institute, Order 1263-MD 810264 (May 1989). Total water includes both tapwater and intrinsic water contained in foods and beverages at the time of purchase. Tapwater includes water consumed directly as beverage and also added to food and beverages during preparation. 27 World Health Organization, Environmental Health criteria 59. Principles for Evaluating Health Risks from Chemicals During Intancy and Early childhood: The Need for a special Approach. Geneva (1986).
with breathing rates and consequently exposure to any contaminates in the air increasing during activity. Finally, the young have proportfonately two and a half times the skin surface area of adults and so can incur greater exposure to contaminants absorbed through the skin while showering or bathing.
In addition to receiving greater exposure, immaturities in their physiological development can render the young more
susceptible to the toxic effects of certain environmental
For example, the human nervous system is still
developing rapidly for several years following birth and is not completely mature until adolescence.29 It is thought that this protracted period of maturation contributes to the sensitivity of the developing brain to various neurotoxins. 50 The young are also especially vulnerable to the effects of many carcinogens released into the environment, principally those that act at the initial stage in the cancer process. Cancer is a multi-stage
30 Reiter, L.W., "Age Related Effects of Chemicals on the Central Nervous System," in Hunt, V.R. et al., eds., Banbury Report lhe Environmental factors in Human Growth and Development, cold Spring Harbor Laboratory (1982). 31 Vesselinovitch, S.D., et al., "Aflatoxin By, a Hepatocarcinogen in the Infant Mouse," Cancer Res., 32:2289-2291 (1972). Vesselinovitch, 8.D., "Perinatal Hepatocarcinogenesis," Bie, Rese in Preg. and Perinatology. 4:22-25 (1983). Vesselinovitch, s.D., et al., "conditions Modifying Development of Tumors in Mice at various sites by Benzo(a)pyrene," Cancer Res., 35:2948-2953 (1975).
disease, and the first stop -- known as initiation -- typically occurs when a carcinogen interacts with genetic material causing a mutation. The young are particularly vulnerable to this first step because cells are dividing rapidly during infancy and early childhood. There is greater probability that a permanent mutation will occur and that the cancer process will begin during periods of rapid cell division. 52
The young are also more vulnerable to so-called "initiating" carcinogens simply because they have a long future life during
Vesselinovitch, S.D., et al., "Carcinogenicity of
Naito, M., et al., "Effect of Age at Treatment on the Incidence and Location of Neurogenic Tumors Induced in Wistar Rats by a Single Dose of N-ethyi-n-nitrosourea," Gann, 72:569-577 (1981).
Mulvihill, J.J., "Ecogenetic Origins of cancer in the Young: Environmental and Genetic Determinants," in Levine, A.S., ed., Cancer in the Young, Marson Publishing (1982).
32 Vesselinovitch, S.D., et al., "Neoplastic Response of Mouse Tissues During Perinatal Age Periods and Its significance in Chemical Carcinogenesis," Perinatal carcinogenesis, National Cancer Institute Monograph 51 (1979).
Chan, P. and T. L. Dao, "Effects of dietary fat on Age-dependent Sensitivity to Mammary carcinogenesis," cancer Letters, 18:245249 (1983).
Laib, R.J., et al., "The Rat Foci Bioassay: Age-Dependency of Induction by vinyl chloride of ATP-Deficient Foci, carcinogenesis, 6:65-68 (1985).
Chang, M.J., et al., "Interrelationships Between Cellular