Endocrine disruption: Where are we now: Tier 2 testing

The focus of this session was on the proposed USEPA Endocrine Disruption Screening Program (EDSP) Tier 2 testing protocols. Tier 2 tests have been developed to evaluate the potential impacts of endocrine disrupting chemicals (EDCs) over the life cycle across organisms representing vertebrate and invertebrate classes. Key aspects of these Tier 2 testing protocols rely on selecting appropriate measurement end points to reveal differential sensitivity and adverse impacts across an organism’s life stages. To this end, certain Tier 2 tests utilize a multigenerational protocol, which detect both short- and long-term effects. However, multigenerational testing protocols can be time consuming and costly. As such, other testing protocols have also been considered, including partial life-cycle and extended one-generation tests. Regardless of the specifics of the multigenerational protocol, it is critical to identify key measurement end points that are responsive, reliable, and repeatable indicators of exposure to endocrine disrupting chemicals; these measures should also provide information to enable initial assessments of risk translated from individual to potential population level effects across a variety of living organisms. Presentations in Session three of the Society of Environmental Toxicology and Chemistry (SETAC) North America Focused Topic Meeting: Endocrine Disruption (February 4 – 6, 2014) focused on the current state of the science for EPA EDSP Tier 2 testing. Presentations in this session considered the strengths and weaknesses of the Tier 2 assays across several classes of organisms, and provided an industry perspective on Tier 2 testing. The interactive panel discussion provided an interesting perspective that balanced regulatory needs for reliable testing protocols that are highly repeatable and utilize consistent indices of exposure and adverse effect.