Air Pollutants and Bay Area School Children: Exposure and Risks Serena Chang Environmental Sciences, University of California at Berkeley Abstract Due to their unique vulnerabilities, children are at greater health risk from environmental exposures to pollutants than any other segment of the population. Characteristics such as physical stature and behavior increase their chances of exposure. For young children generally, the school and home microenvironments contribute most to their exposure to environmental pollutants. Thus, it is important to be aware of the health risks that children potentially face as a result of their exposures at school. The goal of this project was to perform crude risk assessments for Bay Area school children based on their exposure to air pollutants. Air quality monitoring data from the California Air Resources Board (CARB) and the Bay Area Air Quality Management District (BAAQMD) were applied to schools located within three miles of each monitor. These concentrations were compared with both cancer and noncancer benchmarks for various compounds derived from EPA reference values. The results show that all the students in the study are potentially at health risk due to their exposures to air toxics while at school. The probability of developing cancer from exposure to metals was low, less than three per one million. The highest total risk from exposure to volatile organic compounds was approximately 400 per million. Because the study only focused on a select group of pollutants, the actual risks faced by these children are likely to be higher. In the future, a more extensive monitoring network with a wider range of pollutants measured would greatly improve the accuracy and usefulness of this type of risk assessment.Introduction The history of the Clean Air Act indicates that Congress made the protection of public health the sole determinant of acceptable air pollution levels (Committee 1996). The Act mandates that national ambient air-quality standards be set low enough to protect the health of all sensitive groups with the exception of those requiring life-support systems. A sensitive group is defined as one that exhibits “a response to a pollutant at a lower level or to a greater degree than the average response of the general population” (Committee 1996). Sensitivity varies among different ethnic groups, genetic backgrounds, as well as age and childhood experience and development. Age-related differences have a significant effect on metabolism, physiology, developmental stage, behavior, and diet (Goldman 1995). Title III, Section 112 of the 1990 Clean Air Act Amendments (CAAA) defined a list of 189 hazardous air pollutants (HAPs), also called air toxics, (Kelly et al. 1994, Caldwell et al. 1998). They were designated as HAPs because they were known or suspected of causing cancer or other adverse human health effects or damage to ecosystems (Kyle et al. 1999). HAPs include certain volatile organic chemicals, pesticides, herbicides, and radionuclides and have been associated with effects impacting the neurological, reproductive, and developmental systems (Woodruff et al. 1998). They were listed by the EPA to identify source categories for which technology-based, toxic air emission reduction standards would be considered (US EPA 2000, elect. comm.) Title III required regulation of routine and accidental emissions of each HAP from large industrial sources and from small commercial sources (Kelly et al. 1994). The greatest contributor to air pollution in the majority of the United States is the motor vehicle. Compounds such as benzene, an air toxic, are present in gasoline and are emitted to the air when gasoline evaporates or passes through the engine as unburned fuel (US EPA 2000, elect. comm.). In addition to being emitted in unburned fuel, a significant amount of automotive benzene is also released from the incomplete combustion of other compounds in gasoline such as toluene and xylene. Formaldehyde, acetaldehyde, and 1,3-butadiene are not present in fuel but are by-products of incomplete combustion. Stationary point sources of air pollution include power production plants utilizing coal combustion, oil refineries, and industrial engineering facilities (Mott et al.1997). Small businesses such as dry cleaners, auto body shops, and metal recycling plants also emit pollutants into the atmosphere.As a group, children may be even more vulnerable than adults to deleterious health effects due to their unique exposures and susceptibilities (Goldman 1998). Their behavior patterns may put them in a position to receive greater exposures. Compared to adults, children are generally more active, with higher ventilation rates. Even at rest, due to their rapid growth, they have a higher resting metabolic rate and rate of oxygen consumption per unit body weight (International Programme 1986). Thus, even if concentrations of respiratory toxins in ambient air are low, the large quantity of air inhaled by a child may expose the child to large doses of the toxins (Gilliland et al. 1999). In addition, due to their physical stature and typical daily activity, young children generally spend more time close to the ground. Thus, they experience higher exposures to pollutants emitted near ground level such as car exhaust and pollutants with high densities (Mott et al.1997). The potential impacts of such exposure are exacerbated because growing lungs may be more vulnerable to permanent adverse effects (Gilliland et al. 1999). Children may also have decreased detoxification capacity for many chemicals because of metabolic enzyme differences present during development (Weaver et al. 1998). Furthermore, they often do not recognize the significance of respiratory symptoms and will not limit outdoor physical activity during periods of high ambient pollution (Mott et al. 1997). Thus, they are less likely to report exposure-related symptoms (Gilliland et al.1999). The physical locations of exposure should also be considered. With school-age children who often spend a significant amount of time at school, the school’s environment has a direct impact on their exposures. Due to economic reasons, schools are often built on relatively undesirable land where children may receive greater exposures to pollutants (Bearer 1995). The time of exposure may also be a factor; for example, children may receive a greater exposure to ozone due to the
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