Exposure to environmental toxicants can occur through contact with contaminated soil, food, water, or air. Examples throughout the Variations in Susceptibility With Developmental Stages section reflect the special exposure susceptibilities by age group. Table 4 summarizes common sources of contamination for different environmental media, by route; however, it is not exhaustive. Although many potential sources of exposure to environmental toxicants exist, this section will focus on take-home sources of exposure because these sources are an often overlooked, yet important, source of exposure.
The transmission of potentially toxic quantities of industrial chemicals from occupational settings to homes and residences is referred to as take-home contamination. Sometimes thought of as paraoccupational exposure, take-home contamination has been more vividly called "fouling one's own nest." Unlike the types of environmental contamination that might impact many individuals and large geographic areas (e.g., air pollution, spills of industrial chemicals, and accumulations of toxic wastes), take-home contamination most often affects the immediate exposed families of the involved workers.
Take-home contamination can occur even when appropriate precautions seem to be in place. For example, it is not enough that contaminated workers change clothing and shoes before returning home. Because some exposure risks are associated with laundering contaminated work clothes, such clothing should not be brought home to be cleaned. Instead, these clothes should be professionally laundered, preferably as part of the employer's occupational safety program. The hazards of seemingly casual exposure should also be recognized. In addition to laundering clothing at work, showering at work might also be necessary in some work settings to ensure that contaminants are removed from hair and skin.
The most direct form of take-home contamination results when industrial chemicals are carried from the workplace to the home on clothing, tools, shoes, skin, and hair (Chisolm 1978). The nature of the chemical and individual variables (e.g., age and activities) determine which family members are most at risk for developing adverse health effects from exposure. Small children are often most susceptible. For example, numerous reports document
lead contamination among the children of lead workers (Watson et al. 1978; Etzel and Balk 1999). In such cases, preschool children might have blood lead levels equal to or greater than those found in the parent or parents who work with or around lead. Similarly, take-home contamination by mercury-exposed workers involved in thermometer manufacturing has led to the greatest blood levels of mercury documented in young children (Schreiber 2001) and in elevated mercury levels in children whose parents worked in a mercury thermometer plant (Hudson 1987).
A less obvious form of take-home exposure results from industrial chemicals in breast milk. Because human milk contains high levels of fat (about 4%), lipophilic compounds are preferentially taken up into breast milk (Schreiber 2001). For some industrial chemicals, breast milk concentrations are threefold to tenfold greater than corresponding maternal blood levels. Very few instances of harm have occurred in a nursing baby because of the baby ingesting chemicals found in his or her mother's milk. The many benefits to the infant provided by breastfeeding greatly outweigh the risk from possible contaminants in breast milk. Good resources discussing breast milk contaminants and breastfeeding are the AAP Handbook of Pediatric Environmental Health (Etzel and Balk 1999) chapter on human milk and Schreiber (2001).
Workplace asbestos has been linked to asbestosis and mesothelioma in family members of asbestos workers (Anderson et al. 1979; Etzel and Balk 1999). Among spouses of asbestos workers (who may have laundered contaminated clothing) and children at home, radiographic abnormalities consistent with asbestos exposure were almost seven times more frequent than expected. Asbestos take-home contamination can also be persistent. It has been found in the homes of former asbestos workers 20 years after the workers stopped working at the plant.
Chloracne has occurred in the children of workers exposed to trichlorophenol, dioxins, and other polycyclic halogenated compounds (Jensen 1972; Yoshimura 1974; Mocarelli et al. 1991). Contact with the parent's or caregiver's contaminated work clothing was the likely cause of this chloracne. Gynecomastia and breast discomfort occurred in children of workers employed in the manufacture of synthetic estrogens (Budzynska et al. 1967). Children of agricultural workers might have increased exposure to pesticides. In another example, a toddler suffered status epilepticus-type seizures after chewing plastic pellets that had adhered to her mother's work boots (Woody et al. 1986). The pellets contained an explosive compound used in munitions and rockets that were manufactured at the mother's workplace.
