age births are moderately associated with contaminated drinking water (i.e., trihalomethanes) (Bove et al., 2001). Oral clefts, cardiac defects, and complete nasal obstruction (choanal atresia) were found in studies evaluating trichloroethylene-contaminated drinking water (Bove et al., 2001). Food may also contain environmental teratogens. A well-known example is the epidemic of cerebral palsy that followed maternal consumption of fish contaminated with organic mercury in Minimata Bay, Japan (Harada, 1978).

Childhood Exposures

Characterization of exposures over time depends on developmental stage and the mechanism by which the agent produces its effect (EPA exposure guidelines, 2003). Multiple types of exposure may interact to produce their effect by the same mechanism, as for example the exposure to multiple insecticides that interfere with cholinesterases (National Research Council, 1993). Children have unique susceptibilities to chemical exposures (see Box 3-2).

Air Pollutants

Six outdoor air pollutants are regulated by the Clean Air Act: ozone, respirable particulate matter, lead, sulfur dioxide, carbon monoxide (CO), and nitrogen oxides. The effects of repeated or long-term exposure to outdoor air pollutants on the developing lungs of children are not well understood. Indoor air pollution, which is generally not regulated (one notable exception being laws prohibiting indoor smoking in public spaces), results primarily from (1) the products of combustion, such as CO, nitrogen dioxide, particulates, and sulfur dioxides; (2) volatile organic compounds, such as formaldehyde, benzene, and trichloroethylene; (3) the products of tobacco smoking (approximately 3,800 chemicals); and (4) molds.

Health effects from these diverse indoor air pollutants include respiratory irritation with cough and wheezing, exacerbation of asthma, allergic responses, cancer, and central nervous system effects (headache, nausea) (American Academy of Pediatrics, 2003). Exposure to asbestos, leading to lung cancer, is also a concern due to the prevalence of asbestos in schools and some homes (U.S. Environmental Protection Agency, 1987; American Academy of Pediatrics, 1987).

Water Pollutants

Some water pollutants are biological agents, some are chemical agents, and some are radionuclides (physical agents). Biological agents generally come from fecal contamination and include such bacteria as salmonella and E. coli, such viruses as hepatitis A and rotavirus, and such parasites as Cryptosporidium parvum. Chemicals in water include such metals as lead, mercury, and arsenic, such natu-



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