Human Health Effects

There are over 20,000 pesticide products containing 620 active ingredients on the market. Each year, 1 billion pounds of active ingredients in conventional pesticides are applied in the United States. There are over 80,000 existing chemicals on the TSCA inventory and each year an additional 2,000 chemicals are added. Release of these chemicals into the environment through agricultural and nonagricultural application and other means poses serious risks to both human health and ecosystems (e.g., plant and wildlife). Humans are exposed to thousands of these agents either singly or in various combinations every day through air, drinking water, food, and dust. In order to accurately characterize risk from and appropriately regulate the manufacture and use of pesticides and other chemicals, EPA must conduct a cost-benefit analysis for each product. Data needed for such analyses are provided, for the most part, by the manufacturer. It is, however, the responsibility of the Agency to provide detailed data collection protocols. This is accomplished through the publication of test guidelines, which must be developed and periodically reviewed.

Scientific Questions:

• What methods can be used to detect, characterize and quantify adverse human health effects that result from exposure to pesticides and other toxic substances?

• What models can be developed to predict the human health effects of exposure to pesticides and other toxic substances?

• What data can we provide on the health effects of selected pesticides and toxic chemicals, alone or in combination?

Approach: NHEERL research is directly supporting the needs of the Agency related to the requirements of TSCA, FIFRA and the FQPA. We are evaluating existing test guidelines and developing new and improved test methods for incorporation in to the OPPTS test guidelines series, and we are developing mechanistically based models that will predict effects based on existing data, extrapolating to either other populations or to effects of other classes of chemical. Our research will improve directly the quality of the data received from manufacturers and registrants and indirectly the quality of risk management decisions for pesticides and industrial chemicals.

Recent Highlights:

• We demonstrated that the developing rat was more sensitive than the developing mouse to immunosuppressive effects of certain contaminants, which led to the recommendation to include the rat as a test species in immunotoxicity testing guidelines.