Oxygen consumption. Because children have a larger surface-to-volume ratio, they also have a higher metabolic rate and greater oxygen consumption (twice as much for a 6-month-old child as an adult) and minute ventilation, which is volume times respiratory rate (more than three times greater for a newborn than an adult). Exposure to any air pollutant is therefore greater on a weight-adjusted basis. For example, if radon is present, a 6-month-old child will receive twice the exposure of an adult (World Health Organization, 1986.) The increased respiratory exchange is also associated with increased vulnerability to CO poisoning.
Quantity and quality of food and water consumed. Children need to consume more calories and water per pound of body weight than adults given their higher metabolic rate. An average infant consumes 5 ounces of formula per kilogram of body weight (equivalent to an adult drinking 30 12-oz cans of soda a day). If the food or liquid contains a contaminant, children may receive more of it relative to their size than adults, making them particularly vulnerable to pollutants in water. Even the most natural of foods, breast milk, whose salutary benefits have been universally acknowledged (World Alliance for Breastfeeding Action, 1992), is affected by environmental pollutants (Ong et al., 1985; Pluim et al., 1994; Rogan et al., 1986). The diet of children is less diverse and contains more milk products and certain fruits and vegetables than the typical adult diet, and, as a result, children may be exposed to more dangerous levels of pesticides and other chemical residues than adults (Zeise et al., 1991; National Research Council, 1993).
Normal behavioral development. Children’s normal behavioral development also influences environmental exposures. Children typically pass through a stage of intense oral exploratory behavior from about age 6 months to 2 years. This also places children at risk in environments with high levels of lead dust, such as houses painted with lead-based paint (Chao and Kikano, 1993), wood used in playground equipment that is treated with arsenic and creosote (Kosnett, 1990), and toxic ingredients in sand or arts and crafts materials. Given their exploratory nature, ambulatory children may wander into unusual situations for play, such as used drums, mud puddles, and empty lots, environments that have the potential for dangerous exposures. As they become adolescents, they gain more and more freedom from parental authority, often having their physical strength and stamina peak before they acquire the ability to think abstractly (Campbell, 1976). Adolescents often misjudge or ignore risks (Perry and Silvis, 1987), which may result in their placing themselves in situations with greater risk than an adult would willingly face.
water was found to be the cause of lead poisoning in several infants whose blood lead exceeded 10 mcg/dl (Baum and Shannon, 1997; Shannon and Graef, 1992).
Food contaminants can be broadly categorized as either pathogenic or toxic. Pathogenic agents include bacteria, viruses or parasites, bacterial toxins, aquatic organisms that elaborate toxins, and toxins that accumulate in the food chain,