Contact: Lisa Dry (202) 249-6523  
Email: lisa_dry@americanchemistry.com

Weight-of Evidence Assessment Represents Evidence-Based Approach to Risk Determination

WASHINGTON (June 30, 2015) - Today the Environmental Protection Agency (EPA) released its analysis of the results of a battery of tests conducted on 67 List 1 chemicals reviewed under the Endocrine Disruptor Screening Program (EDSP). In 1996, Congress directed EPA to develop a program to determine whether certain substances can lead to hormonal effects in humans that are similar to an effect produced by a naturally occurring estrogen. A two-tiered screening and testing program was developed to form the EDSP. Tier 1 screening was intended to identify chemicals with the potential to interact with the endocrine system, specifically the estrogen, androgen or thyroid signaling pathways. Based on the results of Tier 1 screening, a subset of chemicals could be subject to Tier 2 testing, a higher level of study that involves long-term evaluation using animal testing. The American Chemistry Council (ACC) released the following statement in response to today's announcement:

"The American Chemical Council (ACC) recognizes  today's release of the Tier 1 weight-of-evidence (WoE) data review as a significant milestone in the Environmental Protection Agency's (EPA) Endocrine Disruptor Screening Program (EDSP) . EPA has made it clear that the selection of chemicals for Tier 1 screening is by no means a determination that the substances are harmful.

"The Agency's risk- and exposure-based approach to the EDSP acknowledges that current exposure levels and exposure frequencies are essential elements of risk assessment. This methodology provides welcome clarity to the process and will provide EPA with the information needed to make decisions on whether further testing may be needed for the List 1 substances.

"The weight-of-evidence approach taken by EPA incorporates a holistic approach to evaluate risk. This approach in interpreting the Tier 1 data relies upon the professional judgment of scientists to examine available data, compare Tier 1 screening results, and determine how this evidence fits together to reach a conclusion as to whether a substance has the potential to interact with the endocrine system."

Two solvents represented by ACC,  isophorone and acetone , were subject to Tier 1 screening. For both isophorone and acetone, EPA noted that based on WoE considerations, "there was no convincing evidence of potential interaction with the estrogen, androgen or thyroid pathways." Accordingly, no further screening is necessary to meet the Agency's test order requirements.

Chemical Safety: Endocrine Disruption  | ACC Center for Endocrine Screening and Testing

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