Research to Address Cumulative Risks

A goal of the Human Health Research Program in EPA's Office of Research and Development is to develop and demonstrate the processes, tools, and data needed to understand better how we are affected by the chemical mixtures that we are exposed to in our daily lives.

Although the traditional approach has been to evaluate the risk of a single chemical from a single source (e.g., lead in drinking water), people, in fact, are exposed to mixtures of chemicals from multiple sources. Chemicals may travel from their sources to people by multiple pathways and may be taken into the body through multiple routes, including inhalation, ingestion, or uptake through the skin. A further complication is that chemicals in a mixture may interact with one another to produce effects different or more severe than they would alone. Alternatively, exposure to a mixture of chemicals or to a single chemical by multiple routes may produce an effect greater than would be predicted by simply adding the individual effects together-what could be termed a "synergistic" or "1 + 1 = 3" effect.

EPA scientists are studying how people are exposed to environmental contaminants; the magnitude and timing of these exposures; how exposures translate into tissue dose and relate to potential health effects; how biomarker of exposure results can be used by risk assessors and how exposure biomonitoring results can be used to demonstrate that the Agency's policies and regulatory actions have resulted in improved human health.

Research to Address Cumulative Risks

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