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Priority Setting Overview

Section 408(p) of the Federal Food, Drug, and Cosmetics Act (FFDCA) mandated EPA ''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 effects as [EPA] may designate'' (21 U.S.C. 346a(p)). As outlined in the December 1998 Endocrine Disruptor Screening Program (EDSP) Statement of Policy [FRL-6052-9] [PDF file, 28pp., 228K, About PDF], EPA is following a two-tiered approach in implementing the requirements of section 408(p) of the Federal Food, Drug, and Cosmetic Act (FFDCA) to test these substances, which potentially include an expansive universe of chemicals and mixtures. Because of this broad mandate, EPA sought to develop an approach for prioritizing the many substances for testing under the EDSP.

"Priority setting" in EDSP refers to identifying which chemicals will undergo Tier 1 Screening first. Tier 1 Screening will include a battery of screening assays to identify substances that have the potential to interact with the estrogen, androgen, or thyroid hormone systems. The purpose of Tier 2 Testing is to determine whether the substance may cause endocrine-mediated effects via or involving estrogen, androgen, or thyroid hormone systems, determine the consequences to the organism of the activities observed in Tier 1 Screening, and establish the relationship between doses of an endocrine-active substance administered in the test and the effects observed.

The universe of chemicals identified by Endocrine Disruptor Screening and Testing Advisory Committee (EDSTAC) as potential candidates for the EDSP include:

Because the available laboratories and resources for screening and testing cannot handle the potentially large number of chemicals that may be subjected to screening and testing under the EDSP at one time, EPA needed to develop a strategy for prioritizing chemicals for screening. A proposed strategy for initial chemical selection for Tier 1 Screening was published in a Federal Register Notice [FRL-7286-6] [PDF file, 19pp., 119K, About PDF], in December 2002. Upon review of comments received in response to the proposed approach, EPA published a final approach for the initial selection of chemicals in a Federal Register Notice [PDF file, 17pp., 125K, About PDF] in September 2005.

EPA published the draft list of initial pesticide active ingredients and pesticide inerts to be considered for screening under the Federal Food, Drug and Cosmetic Act for public notice and comment in a 2007 Federal Register Notice [PDF file, 18pp., 131KB, About PDF]. The draft list was produced using the approach described in the September 2005 Federal Register Notice [PDF file, 17pp., 125KB, About PDF], and includes chemicals that the Agency has decided should be tested first, based upon exposure potential.

EPA published the final list of initial pesticide active ingredients and pesticide inerts for screening under the Federal Food, Drug and Cosmetic Act in a Federal Register Notice on April 15, 2009 [PDF file, 18pp., 131KB, About PDF]. The final list includes revisions made after considering public comments submitted to EPA during a public comment period on a draft version of the list. The list of chemicals selected for initial screening includes pesticide active ingredients and High Production Volume (HPV) chemicals used as pesticide inerts.

The final list (as well as the draft list) should not be construed as a list of known or likely endocrine disruptors. Nothing in the approach for generating the list provides a basis to infer that any of the chemicals selected interfere with or are suspected to interfere with the endocrine systems of humans or other species.

EPA anticipates that it may, in the future, modify its approach to selecting chemicals for screening. Information and factors that EPA may consider in selecting chemicals could include: public input; the results of testing chemicals on the initial list; management considerations to increase the integration of screening with other regulatory activities; implementation considerations flowing from a decision to extend screening to additional categories of chemicals (e.g., nonpesticide chemical substances); and the availability of new priority-setting tools (e.g., High Throughput Pre-Screening (HTPS) and Quantitative Structure Activity Relationships (QSAR) models).

You will need the free Adobe Reader to view some of the files on this page. See EPA's PDF page to learn more. If you need help accessing these PDF documents, please contact William Wooge at 202-564-8476 or wooge.william@epa.gov for assistance.

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