Like most regulatory agencies, EPA relies heavily on animal studies for assessing the potential health risk from a particular chemical. Various strains of rats and mice are dosed with various concentrations of a chemical and the effect assessed; using well established toxicological principles, implications for risk to humans can be drawn from the test results. However, this process has been criticized. As noted in a 2008 GAO report [http://www.gao.gov/products/GAO-08-743T], a combination of changing scientific methods, bureaucratic gamesmanship, and a reluctance to move forward on evaluations meant that many studies did not happen, had to be repeated, or were accomplished only after the passage of much time.
Thus, EPA recently took the lead in commissioning the National Research Council (NRC) of the National Academies of Science to develop a long-range vision for toxicity testing and risk assessment. Their 2007 report, Toxicity Testing in the 21st Century: a Vision and a Strategy [see http://books.nap.edu/openbook.php?record_id=11970], envisioned a transformation that focused on identifying and evaluating "toxicity pathways," i.e., cellular response pathways responsible for adverse health effects when sufficiently perturbed by environmental agents under realistic exposure conditions.
To build upon the changes advocated in the NRC study, EPA established a workgroup under the auspices of its internal Science Policy Council. This workgroup produced The U.S. Environmental Protection Agency's Strategic Plan for Evaluating the Toxicity of Chemicals that provides a framework for EPA to comprehensively move forward to incorporate this new scientific paradigm into future toxicity testing and risk assessment practices. A copy of the Plan can be found at http://www.epa.gov/OSA/spc/toxicitytesting/docs/toxtest_strategy_032309.pdf.
This “new paradigm” has the potential to address increasingly complex issues that EPA faces in evaluating environmental contaminants for risks to human health and the environment. For example, it is expected to create more efficient and cost-effective means to screen and prioritize for further assessment the tens of thousands of chemicals that are already found in the environment. It should [emphasis on should] facilitate evaluating the susceptibility of different life-stages and genetic variations in the population, understanding the mechanisms by which toxicity occurs, and considering the risks of concurrent, cumulative exposure to multiple and diverse chemicals, while at the same time significantly reducing reliance on animal testing for assessing human risk.
This Plan is centered on three interrelated components: (1) the use of toxicity pathways identification and use of this information in screening and prioritization of chemicals for further testing; (2) the use of toxicity pathways information in risk assessment; and, (3) the institutional transition necessary to implement such practices across EPA. This Plan describes an ambitious and substantive improvement in the efficiency and effectiveness of the process by which environmental pollutants are evaluated for toxicity and risk. According to the NRC, the strategic plan will require funding of up to $100 million per year for 10-20 years in order to have a reasonable chance of success.