EPA Defends Chemical Testing of Low-Dose Hormone Effects

The agency is responding to a report written by 12 scientists who criticized the governments decades-old strategy for testing the safety of many chemicals found in the environment and consumer products

Flickr/Victor Bayon

The U.S. Environmental Protection Agency has concluded that current testing of hormone-altering chemicals is adequate for detecting low-dose effects that may jeopardize health.

This comes in response to a report written last year by 12 scientists who criticized the governments decades old-strategy for testing the safety of many chemicals found in the environment and in consumer products.

The scientists specifically focused on a phenomenon called nonmonotonic dose response, which means that hormone-like chemicals often do not act in a typical way; they can have health effects at low doses but no effects or different effects at high doses. The EPA frequently evaluates the risks of chemicals with tests that expose lab animals to high doses, then extrapolating to lower doses that people and wildlife encounter.

Dozens of substances that mimic or block estrogen, testosterone or thyroid hormones are found in the environment, food, pesticides and consumer products. The idea that these chemicals harm people at tiny doses remains controversial.

The EPAs draft State of the Science report, completed last week, found that such low-dose responses do occur in biological systems but are generally not common.

There currently is no reproducible evidence that the low-dose effects seen in lab tests are predictive of adverse outcomes that may be seen in humans or wildlife populations for estrogen, androgen or thyroid endpoints, the agency report said. Therefore, current testing strategies are unlikely to mischaracterize...a chemical that has the potential for adverse perturbations of the estrogen, androgen or thyroid pathways.

The report was written by EPA officials with input from a team of scientists and managers from the Food and Drug Administration, the National Institute of Environmental Health Sciences and the National Institute of Child Health and Development that reviewed the science on endocrine-disrupting chemicals. It was signed by Robert Kavlock, the EPAs Deputy Assistant Administrator for Science.

The federal team was commissioned last June in response to the scientists report published a few months earlier by lead author Laura Vandenberg, a Tufts University researcher, and colleagues. Pete Myers, founder of Environmental Health News and chief scientist at Environmental Health Sciences, was the senior author of that report.

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EPA Defends Chemical Testing of Low-Dose Hormone Effects

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