Endocrine Disruptor Screening Program (EDSP) Tier 1 Assessments

The EPA has released its reviews of the Tier 1 screening assay results for the first 52 pesticide chemicals (active and inert ingredients) in the Endocrine Disruptor Screening Program. This is an important step in a multi-step process to protect public health and the environment by ensuring that exposure to chemicals do not result in adverse effects that can occur from the disruption of hormones.

The Tier 1 screening data are the best way to determine whether a chemical has the potential to interact with the endocrine system and requires more thorough testing.

For each chemical, EPA decides whether additional (Tier 2) testing is necessary. These decisions are based on weighing whether the evidence from the assay results, as well as other scientifically relevant data, showing more potential for endocrine bioactivity outweighs the evidence that it does not.

• What action is EPA taking?
• What did EPA find?
• What tests were conducted on these chemicals during Tier 1 screening?
• What do the test results mean? 
• Will EPA require further testing on these chemicals?
• Where can I find the Tier 1 screening results for the chemicals tested?
• Contacts

What Action is EPA Taking?

EPA is releasing Tier 1 screening results for 52 chemicals included in the Endocrine Disruptor Screening Program (EDSP). Tier 1 test orders were originally issued for 67 chemicals. However, 15 of these chemicals were subsequently canceled or discontinued by the pesticide registrant and are no longer in use.  This is an important step in a multi-step process to protect public health and the environment by ensuring that exposure to chemicals does not result in adverse effects that can occur from the disruption of hormones.  

What did EPA Find?

Of the 52 chemicals evaluated, there was no evidence for potential interaction with any of the endocrine pathways for 20 chemicals, and for 14 chemicals that showed potential interaction with one or more pathways, EPA already has enough information to conclude that they do not pose risks. 

Of the remaining 18 chemicals, all 18 showed potential interaction with the thyroid pathway, 17 of them with the androgen pathway, and 14 also potentially interacted with the estrogen pathway.

What Tests Were Conducted on These Chemicals During Tier 1 Screening?

EDSP’s Tier 1 screening is used to determine if chemicals have the potential to interact with the three hormonal pathways in the body’s endocrine system – estrogen, androgen and thyroid pathways. 11 assays, five in vitro (cell systems) and six in vivo (live animal) are used to determine whether these chemicals interact with these three hormone pathways. We look at the results of this data as well as other scientifically relevant information, including general toxicity data and open literature studies of sufficient quality.

Learn more about EDSP’s Tier 1 screening process.

What Do the Test Results Mean?

The purpose of Tier 1 screening is to identify chemicals that have the potential to interact with the estrogen, androgen or thyroid hormonal systems. The screening results for these 52 chemicals are only determinations of their potential to disrupt endocrine function. A result indicating potential should not be construed as meaning that EPA has concluded that the chemical is an endocrine disruptor.

EPA plans to require additional testing, known as Tier 2 testing, for chemicals that we have decided need more test data in order to fully understand their impacts on the endocrine system.

Will EPA Require Further Testing on These Chemicals?

EPA is recommending additional testing, known as Tier 2 testing, for 18 chemicals to help the agency better understand the potential of these chemicals to cause adverse effects through interaction with the endocrine system. Additional tests include:

• A comparative thyroid assay for four chemicals that showed interaction with the thyroid pathway in mammals.
• A medaka one-generation reproductive test for 13 chemicals that showed interaction with the estrogen or androgen pathways in wildlife.
• A larval amphibian growth and development assay for five chemicals that showed interaction with the thyroid pathway in wildlife.

The table below summarizes the chemicals and tests that EPA will require. Tier 2 testing will not be required for those chemicals that EPA has found to have little or no impact on the endocrine system. It’s important to note that endocrine disruptor screening is just one category of testing EPA conducts on chemicals to determine their health and environmental impacts.

Chemicals in this list of 52 that do not require further endocrine disruptor testing could still require other testing as part of the risk assessments conducted by EPA. View the status of EDSP orders and data call-in notices

Where Can I Find the Tier 1 Screening Results for the Chemicals Tested?

Tier 1 Screening results and associated data evaluation records (DERs) for 52 Tier 1 chemicals are available for review. The collection of documents are organized, by chemical, in a searchable table with links to related documents.

Contacts

• Regulatory questions: Jolene Trujillo, Chemical Review Manager, Pesticide Re-Evaluation Division, at trujillo.jolene@epa.gov or (303) 312-6579
• Human health effects: Jess Rowland, Deputy Division Director, Health Effects Division, at Rowland.jess@epa.gov or (703) 308-2719
• Ecological effects: Amy Blankinship, Senior Scientist, Environmental Fate and Effects Division, at Blankinship.amy@epa.gov or (703) 347-8062