How EPA Prioritizes Chemical Risk Assessments - ChemicalSafetyFacts.org
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The Toxic Substances Control Act (TSCA) is the United States’ primary chemical management law. In 2016, the Frank R. Lautenberg Chemical Safety for the 21st Century Act, which modernized TSCA, was signed into law after passing in Congress with overwhelming bipartisan support. The amended TSCA requires the U.S. Environmental Protection Agency (EPA) to undertake a safety review of all new and existing chemicals, and it requires the agency to identify chemicals that are high- and low-priority for risk evaluations.

The three stages of EPA’s process for evaluating the safety of existing chemicals are: 1) prioritization, 2) risk evaluation and 3) risk management. The third stage is only necessary when EPA finds that a chemical poses an unreasonable risk to human health or the environment.

What are High- and Low-Priority Chemicals?

The prioritization process for high- and low-priority substances is a key component of EPA’s ability to conduct a systematic evaluation of chemicals in commerce. Designation as a low-priority substance means the agency has determined that chemical does not require a risk evaluation at the time, but can be reconsidered based on new information in the future. 

A high-priority designation, on the other hand, means that EPA will initiate a TSCA risk evaluation of the substance. It is important to note that—as EPA has said—designation of a substance as a high priority “does not constitute a finding of risk” and should not be cause for concern.

TSCA requires that at least 50 percent of all high-priority designations be drawn from the 2014 Update of the TSCA Work Plan and that EPA give preference to those chemicals that have a persistence and bioaccumulation score of three, are a known human carcinogen, or have high acute or chronic toxicity.

The entire prioritization process for a chemical—from announcement of a potential candidate to final designation of a priority—may take from 9–12 months. EPA must use the best available science and the weight of the scientific evidence, as required by the 2016 TSCA amendments, to determine which chemicals are high and low priority.

What is a Risk Evaluation?

TSCA requires risk evaluations for existing chemicals in commerce. Risk evaluations must integrate hazard information with use and exposure information of a designated high priority substance to determine whether or not the chemical presents an unreasonable risk to health or the environment under the chemical’s conditions of use. EPA cannot consider non-risk factors (e.g., costs/benefits) during the risk evaluation.   EPA must consider risks to potentially exposed or sensitive subpopulations in the risk evaluation, such as children and workers. Further, risk evaluations must be grounded in the best available science and the weight of the scientific evidence as required by Section 26 of the statute. Details about the risk evaluation process and timeline can found on EPA’s website.

A chemical risk evaluation can take up to three years. During the TSCA risk evaluation process, chemical manufacturers, processors, importers and downstream users will have opportunities to provide data, information and public comments to EPA for its consideration. Upon completion, EPA must designate another high-priority chemical to the list, to ensure the risk evaluation queue remains full. Think of the prioritization and risk evaluation processes as operating like a conveyor belt, meant to ensure EPA is continually designating priority substances and conducting risk evaluations. 

What is Risk Management?

If the risk evaluation determines that a chemical presents an unreasonable risk to human health or the environment under the conditions of use evaluated, EPA must undertake a risk management process to mitigate the unreasonable risk identified.

During the risk management process, EPA has a variety of options for regulatory restrictions available to it to reduce risk.  This could include requirements regarding how the chemical can be used in products, labeling requirements, use restrictions, phase-outs or outright bans on use of the chemical in products. 

Key Takeaways:

  • A high-priority designation does not mean a chemical is poses any risk. EPA has made clear that designation as a high priority chemical “does not constitute a finding of risk” and should not be cause for concern.
  • EPA must conduct risk evaluations for high priority chemicals that integrate hazard information with use and exposure information on the chemical. Consideration of costs or other non-risk factors must be excluded. Scientific information and approaches must be used in a way that is consistent with the requirements of TSCA regarding the best available science and weight of the scientific evidence. 
  • EPA will designate a high priority chemical when another chemical’s risk evaluation is completed. This ensures that EPA’s risk evaluation queue always remains full, e.g., conducting at least 20 at any given time. 
  • EPA has several risk management options available to control or mitigate any unreasonable risks identified of a chemical under its conditions of use.