March 17, 2003

Endocrine Disruptor Screening Program: Proposed Chemical Selection Approach for Initial Round of Screening

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Endocrine Disrupter Screening Program: Proposed Chemical Selection Approach for Initial Round of Screening 

Stated Purpose:

To determine "whether certain substances may have an effect in humans that is similar to an effect produced by a naturally occurring estrogen, or such other endocrine effect as the [EPA] Administrator may designate."

Summary of RSP Comment:

Research has demonstrated that some chemicals, dubbed "endocrine disruptors," can interfere with animals’ hormone systems, potentially causing adverse health effects. EPA created the Endocrine Disruptors Screening Program (EDSP) to comply with a Food Quality Protection Act (FQPA) of 1996 requirement to screen all chemicals used in pesticides.

Because of the difficulty in replicating low-dose studies (those at exposure levels typical of the everyday environment), and the attendant uncertainty over whether they represent a real phenomenon, EPA does not intend to assess low-dose effects as part of the EDSP. Yet in terms of protecting public health, low-dose effects are the key issue. Human exposures to chemicals are typically hundreds to thousands of times lower than levels expected to be toxic based on "classical" toxicology studies. Thus, if there are no adverse low-dose effects, the EDSP is unlikely to generate new policy-relevant information, and the funds spent on the program (potentially billions of dollars) will have been wasted. At the same time, the EDSP has great potential to spuriously stigmatize chemicals that are genuinely safe, which could ultimately harm consumers by raising the costs of foods and other consumer products produced with the aid of the relevant chemicals. A large-scale chemical screening program would thus be useful only if the evidence suggests that low-dose effects exist.

Thus, EPA should limit the EDSP only to those chemicals for which testing is mandated, and include only those additional chemicals for which low-dose effects have been reported in at least one laboratory animal study in the peer-reviewed literature that used realistic routes of exposure. The first 50-100 chemicals should include a broad universe that samples a range of expected endocrine activity, biochemical modes of action, and toxicity. The selection process should also ensure inclusion of chemicals with widespread human exposure, but for which there are few or no toxicity data.

Though not mandated by statute, EPA would do a greater service to public health by focusing some resources on assessing whether low-dose effects actually occur in mammals and under what conditions and species, and, if so, whether the observed effects are adverse.