EPA researchers develop methods for testing chemicals for potential endocrine disruption. These tests range from tests on animals to chemical assays (in a test tube or chemical well plate). EPA researchers have developed whole-animal tests, such as a 21-day test which is now being used as part of the EPA's endocrine disruptor screening program's Tier 1 tests.

21-Day Test on Fathead Minnows

This 21-day test on fathead minnows is designed to detect changes in fish and their spawning behavior, as well as specific biochemical endpoints that reflect disturbances in hormonal systems. The results of this test are useful for assessing potential effects of a chemical or mixture of chemicals on aquatic organisms and in some cases human health as well, given that fish and humans have similarities in their reproductive hormonal systems.

Protocols for Tier 2 Testing

EPA researchers have also 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 fertility, secondary sex characteristics, etc.

Amphibian Tests

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. After input from a Scientific Advisory Panel, the two tests can be used 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.