Low Dose Effects / Non-Monotonic Responses of Endocrine Disruptors
October 24, 2014
Searle Center Lecture Hall, Duke University
ABSTRACT: The publication of “Our Stolen Future” helped to spur research on endocrine disrupting contaminants (EDCs) and investigating their potential affects on human health and development. In the 1990s, the Environmental Protection Agency developed an Endocrine Disruptor Screening Program to evaluate pesticides and chemicals in commerce for their ability to disrupt the endocrine system. In classical toxicology research, it is often assumed that increased exposures will correlate with an increase in effect or toxicity. However, some research studies have challenged this dogma, suggesting that some EDCs can have greater effects at low doses relative to high doses, an effect known as a non-monotonic dose response (NMDR). Interpretation of these results is challenging, particularly within regulatory landscapes and risk assessment frameworks that operate under the assumption of a linear relationship between exposure dose and adverse effect. In 2013, EPA charged a group of scientists to review the published scientific literature and write a paper on the state of the science on NMDRs. One of the key goals of this exercise was to identify whether or not NMDRs occur, and if so, under what conditions. A draft paper was written by the EPA and then reviewed by the National Academy of Sciences in 2014. This symposium will highlight several studies on NMDRs, and discuss the findings of both the EPA paper and NAS evaluation of this report.