Science Wednesday: EPA Risk Assessments, the Best Possible Science

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By Paul T. Anastas, Ph.D.

A dedicated team of scientists in EPA’s Integrated Risk Information System (IRIS) program works to assess the hazards that chemicals pose to human health. The assessments they produce, known as IRIS assessments, are not regulations. However, the information they contain is an important basis for regulatory decisions that impact the health of all Americans.

The importance of this hazard information—such as whether or not a chemical is likely carcinogenic—cannot be overstated.
Because some assessments focus on chemicals that are widely used in industry, members of the regulated community, environmental groups, the media, and the public have shown keen interest in the IRIS program. Their interest is legitimate. All Americans should be armed with the best possible scientific information on chemical hazards and feel confident that EPA is striving for continuous improvement.

EPA also solicits feedback on draft IRIS assessments from independent scientific experts. While their feedback has been largely positive, when issues are identified, we act to address them. This is precisely the reason EPA submits draft assessments for independent review. This means the scientific process is working.

This summer, EPA announced a set of improvements to the IRIS program in direct response to recommendations from the National Academies of Science and other independent experts. These changes make IRIS assessments clearer, more concise, and make our methods and scientific assumptions more transparent to readers. We have already begun to phase-in these changes to assessments in the IRIS pipeline.

Of the 50 chemicals currently in the IRIS pipeline, several are exceedingly complex. For example, the IRIS assessment of trichloroethylene (TCE), a widely used industrial solvent, has been under development for more than a decade. The assessment is of high interest because of its potential implications for industry and public health. After extensive independent review, it has been determined that any issues have been adequately addressed.

The TCE IRIS assessment is being released today. It concludes that TCE is carcinogenic to people and poses a human health hazard to the central nervous system, kidney, liver, immune system, male reproductive system, and the developing fetus. This information will be useful to communities, businesses, and government leaders across the country as they make important decisions that impact human health and the environment.

While we know that the goal of perfection is impossible, we will continue to strive for it. We will continue to release IRIS assessments that are scientifically strong. We will continue to pursue the best science with integrity and a mission to protect the health of the American people.

About the author: Paul T. Anastas, Ph.D. is the assistant administrator for EPA’s Office of Research and Development and the science advisor to the Agency.

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