The environment in which a child lives can be defined in several different ways. Environmental science definitions recognize that children interact with multiple physical, chemical and biological factors. Sociocultural definitions also take into account demographic characteristics such as the home environment, race, ethnicity, rural/urban status, and poverty. CEHI recognizes that both definitions highlight factors that interact to determine the general health and well-being of children.
With increased industrialization, population growth, and technological innovation, the array of environmental contaminants that children are exposed to continues to grow. Children may be exposed to agricultural pesticides, groundwater contaminants, residues from chemical use, and air toxins from manufacturing facilities. The chemicals involved in these exposures may originate at one location and migrate great distances at rates and levels influenced by physical characteristics of the local environment. They may also include long-term historic residues. Exposures to environmental contaminants can also occur within the home environment. Such exposures include lead-based paint, allergen and asthma triggers, environmental tobacco smoke, and indoor pesticides. While exposures occurring within the home may have solutions that are within the direct control of the resident or homeowner, exposures outside the home environment are often beyond the control of individuals.
Although everyone, regardless of age, comes in contact with a multitude of environmental contaminants, the special vulnerabilities of children make their exposures of particular concern. The behavior patterns specific to children, such as hand-to-mouth activity or poor hand-washing, can result in their being exposed to more of toxicants than adults. Physiological characteristics, such as rate of chemical absorption and high consumption of food and water relative to body mass/volume, also result in children being more highly exposed to certain contaminates. In addition, the immature developmental status of children's respiratory, reproductive, immune, and nervous systems make them more likely to express toxic effects. These special vulnerabilities of children make it essential that research specifically address children's environmental health, as distinct from environmental health research more generally.
A variety of patterns and processes acts to combine environmental exposures in ways that make it difficult to disaggregate subsequent health effects on children. In addition, exposures to environmental contaminants may co-occur with social stressors. For example, a deprived home environment may exacerbate the effects of exposure to neurotoxins and other contaminants; while enriched, nurturing home environments may be protective against such effects. The extent to which this holds depends on the full suite of risk and mitigative factors, including the special vulnerabilities of the exposed individual, the severity of the exposure, and the particular environmental toxicant. In addition, a feedback loop may exist in that the psychosocial stress induced by symptoms of exposure and participation in a treatment regime may affect those aspects of the child's environment that might otherwise serve a protective role. For example, children exposed to lead place heavy burdens on caretakers and may overwhelm the personal, professional, and financial resources available to parents, significantly affecting their ability to provide a supportive home (and child care) setting.