Testing & Prioritizing Chemicals: In-depth Analysis
EPA researchers are studying how exposure to endocrine disrupting chemicals (EDCs) may affect human health and the environment. They are developing chemical tests that can be used to evaluate the potential for chemicals to interfere with the endocrine system. EPA's Endocrine Disruption Screening Program has developed a two tiered testing approach. Tier 1 identifies chemicals that have the potential to interact with the endocrine system. Tier 2 does a more in-depth analysis of chemicals flagged in Tier 1 to determine the endocrine-related effects caused by each chemical at different levels of exposure.
EPA scientists developed protocols for Tier 2 testing to assess how chemicals affect the endocrine system of fish and amphibians.
For fish, scientists created the Medaka Multi-Generation Test. This test provides concentration-response information related to the adverse effects in fish after they are exposed to various concentrations of potential endocrine disrupting chemicals in water. Examples of adverse effects are changes to the integrity and performance of male and female reproductive systems, including fecundity, fertility, secondary sex characteristics, biochemical liver responses, histopathology of several tissues and growth and development that are relevant to all life stages, and subsequent generations.
For amphibians, scientists constructed the Larval Amphibian Growth and Development Test.
This test provides concentration-response information related to the adverse effects in amphibians after they are exposed to various concentrations of potential endocrine disrupting chemicals in water. Examples of these effects are changes to larval development and metamorphosis, juvenile growth and development, including secondary sex characteristics, biochemical liver responses, thyroid function, and histopathology of several tissues.
Results and Impact
After EPA’s Scientific Advisory Panel review process, these two tests can be used by EPA’s Endocrine Disruptor Screening Program (EDSP) to determine if chemicals identified by Tier 1 tests may pose a risk to the endocrine system of fish, amphibians and other aquatic species found in lakes, streams and rivers. The ultimate purpose of the EDSP is to develop screening and testing requirements for evaluating pesticides, commercial chemicals and environmental contaminants for their potential to disrupt the endocrine system.