This paper is one of five in a “Special Series on Endocrine Disruption: Chemical Testing, Risk Assessment Approaches and Implications” about the Society of Environmental Toxicology and Chemistry (SETAC) focused topic meeting held 4-6 February, 2014 in Raleigh, N.C., USA. The series addresses 1) the status of the United States Environmental Protection Agency’s Endocrine Disruptor Screening Program (EDSP), 2) how data from both EDSP-directed testing and other sources may be interpreted and applied in regulatory settings and c) approaches for moving beyond estrogen, androgen and thyroid pathways to address current challenges and expanding future approaches to testing endocrine-disrupting chemicals (EDCs).
In response to the requirements of the EDSP, Tier 1 assays have been performed with a number of pesticides over the past several years. These assays are designed to be used in concert as a screen for potential interactions with vertebrate estrogen, androgen and thyroid systems. The results of the 11 assays in the Tier 1 battery are then used, along with other lines of evidence, to determine whether a chemical is endocrine-active and, as a consequence, might be a candidate for Tier 2 testing. The EDSP is based on scientifically credible, transparent approaches for conducting weight-of-evidence analyses and approaches for framing the hypotheses, evaluating the data, assigning weight to different endpoints relative to their diagnostic effectiveness and assessing confounding factors. In recognition of the cross-species conservation of the hypothalamic-pituitary-gonadal axis among vertebrates, a subset of the Tier-1 in vivo assays may be useful for more rapidly screening chemicals for potential endocrine activity.