Screening Pesticides for Estrogenic and (anti)Androgenic Activity in Support of Endocrine Disruptor Screening Program (EDSP) Revival
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EPA’s Endocrine Disruptor Screening Program (EDSP) was established in 1998 to identify chemicals that disrupt human endocrine system signaling. EDSP has the potential to support the regulation of pesticides under FIFRA, the Federal Insecticide, Fungicide, and Rodenticide Act. Out of 403 pesticides undergoing FIFRA review in 2023, 317 lacked adequate reproductive toxicity data, including 30 pesticides with potential estrogenic (human estrogen receptor; ER) and/or androgenic activity (human androgen receptor; AR) identified by high-throughput screening (HTS). EPA plans to utilize these 30 pesticides as a pilot program to revive EDSP’s tiered testing protocol. We propose to use sensitive, validated in vitro cell-based bioassays to supplement HTS data for this group of pesticides and compare purported antagonist activity with cytotoxicity, run concurrently. To assess ER agonist activity, we will utilize the T47D-kbluc transcriptional activation luciferase reporter gene assay. T47D-kbluc cells express both ER-alpha and ER-beta and were stably transfected with an ER-sensitive luciferase reporter gene. AR agonist and antagonist activity will be measured with the CV1-chAR transcriptional activation luciferase reporter gene assay. CV1 cells will be transfected with a replication-deficient adenovirus carrying an androgen receptor gene (Ad5chAR) and androgen-sensitive luciferase reporter gene (Ad5mLuc). ER and (antagonist) AR activity will be quantified by measuring the luminescence of the luciferase-expressing cells. For pesticides exhibiting AR antagonist activity, the transcriptional activation assay will be run alongside a rapid colorimetric cytotoxicity assay. These Tier 1-type in vitro assays enable us to efficiently and accurately screen for pesticides that pose the greatest health risk and appropriately allocate resources for Tier 2 testing. Furthermore, the tiered testing approach used to assess these pesticides provides a model for the continued expansion of EDSP. The views expressed in this abstract are those of the author(s) and do not necessarily represent the views or policies of the U.S. Environmental Protection Agency.