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Recently, intense attention has been given to children's health issues, particularly in the use of consumer products. Because of this attention, researchers have been planning and initiating studies specifically aimed at developing both toxicology data and exposure data directed to improve our understanding of industrial and consumer product chemical impacts on children's health. To ensure that this research is focused on the highest priority chemicals, we present a methodology for determining and prioritizing the higher hazard chemicals and scenarios for which children could be disproportionately or highly exposed. This tiered approach includes a screening step for initial chemical selection, a hazard assessment based on no- or lowest-observed-adverse-effect levels, and a margin of exposure (MOE) calculation. The initial chemical screen focuses on the chemical presence in specific media that are special to children, such as foods children regularly eat and drink, residential or school air, products children use, and soil and dust in and around residences. Data from the literature or from models serve as the initial exposure estimate. This methodology would allow us to focus on those chemicals to which children are most exposed that are also associated with, potentially, the highest risk. Use of the MOE calculation allows for comparison among chemicals, prioritization of chemicals for evaluation and testing, and identification of significant data gaps.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD or dioxin), a highly publicized environmenta l contaminant, was shown to be chemoprotective against breast cancer in both rats and mice in bioassays conducted in the late 1970s. This nding went largely unnoticed as investigators focused on animal tumors that were increased by dioxin. The position that dioxin causes human tumors remains a subject for debate; however, recent epidemiological studies of a population highly exposed to dioxin in 1976 as a result of an industrial accident suggest that women with higher dioxin body burdens may have a lower incidence of breast cancer. With the growth of new knowledge about the molecular basis of dioxin actions in humans and animals, it is clear that most of the responses produced by this agent are initiated by a speci c recognition protein (designated the Ah receptor) found in almost all animal and human tissues and organs. The recognition event between the Ah receptor and environmental agents like dioxin is due to the formation of a complex. We have observed that in the presence of dioxin, the Ah receptor turns off proliferation in tumor cells and suppresse s the ability of these cells to invade normal tissue. We believe that these ndings provide a molecular and biochemica l basis for understandin g the chemoprotective mechanism s suggested by the ndings of rodent bioassays and could lead to the developmen t of novel therapeutic agents targeting the Ah receptor.

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Recendly, intense attention has been given to children's health issues, particularly in the use of consumer products. Because of this attention, researchers have been planning and iniiai studies specifial med at developing both toxicology data and exposure data directed to improve our understanding of industial and consumer product chemical impacts on chidren's health. To ensure that this research is focused on the highest prioriy chemicals, we present a methodology for determining and prioritizingdthe higher hazard, chem;icals and scenarios for which children could be disproportionately or highly exposed. This tiered approach indudes a screening step for initial chemical selection, a hazard assessment based on no-or lowest-observed-adverse-effect levels, and a margin of exposure (MOE) calculation. The initial chemical screen focuses on the chemical presence in specific media that are special to cildren, such as foods children regularly eat and drink, residential or school air, products children use, and soil and dust in and around residences, Data from the literature or from models serve as the initial sexpoure estimate. This methodology would allow us to focus on those chemicals to which children are most exposed that are also associated with, potentially, the highest risk Use ofthe MOE calculation allows for comparison among chemicals, prioritization of chemicals for evluation and testin& and identification of significant data gaps. Key work assessment, chemical, children, exposure, exposure factors,