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Endocrine Disruption

Endocrine Disruptor Screening Program (EDSP) in the 21st Century

Beginning in 2012, the Endocrine Disruptor Screening Program (EDSP) began a multi-year transition to validate and more efficiently use computational toxicology methods and high throughput screens that will allow EPA to more quickly and cost-effectively assess potential chemical toxicity. The initiative, referred to as EDSP21 – or EDSP in the 21st century – aims to use computational or in silico models and molecular based in vitro high-throughput screening (HTS) assays to prioritize and screen chemicals to determine their potential to interact with the estrogen, androgen or thyroid (E, A, or T) bioactivity. In addition to leveraging advances in technology, the initiative also emphasizes strategic coordination and timing of chemical evaluations in the context of existing regulatory frameworks.

For pesticides, EPA’s strategy is to coordinate the timing of issuance of EDSP Tier 1 test orders with the timing of the registration review program. By issuing test orders for an active ingredient before the start of the registration review process for the active ingredient, the results of any EDSP Tier 2 tests that might be needed for the active ingredient should be available for agency scientists to review when they are also examining the toxicology database to develop updated and more expeditious risk assessments.

Reviewing both sets of data concurrently will reduce duplication of effort and lead to decisions more expediently. However, the time needed to fulfill test order requirements using the current validated Tier 1 assays can make it challenging to integrate data from the current EDSP Tier 1 assays into the reregistration review of some pesticides. This would mean that the data for some active ingredients may not be available early enough to be easily integrated into their registration review.

It is envisioned that the EDSP21 program, along with a combination of existing data, and in silico and in vitro methodologies, will enable the agency to prioritize and identify EDSP Tier 1 information needs for pesticide active ingredient cases entering the registration review program over the next several (1-3) years.

In addition to the above chronology-based approach and prioritization for pesticide active ingredients, EDSP21 proposes a method to prioritize and screen non-pesticide active ingredient chemicals as well as pesticide chemicals. The approach is based on advances in computational modeling and molecular biology, understanding of endocrine-specific initiating events and adverse outcome pathways, as well as robotics for conducting rapid in vitro assays on hundreds of chemicals simultaneously. 

EPA researchers developed the Endocrine Disruption Screening Program for the 21st Century Dashboard (EDSP21 Dashboard) to provide access to new chemical data on over 1,800 chemicals of interest. The purpose of the EDSP Dashboard is to help EPA evaluate chemicals for endocrine-related activity. Access the EDSP21 Dashboard and select a chemical to view its chemical summary, regulatory lists, bioactivity results, high throughput exposure results, as well as detailed descriptions of EDSP assays.

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