Chemical Prioritization and Evaluation Rules Issued by EPA

The EPA has finalized two rules required by the amended Toxic Substances Control Act (TSCA), which are intended to guide the Agency in both prioritizing chemicals for risk evaluations and actually conducting those evaluations.

Both rules apply only to the EPA, and the regulated community is not specifically affected. However, the outcome of prioritization and risk evaluation has major consequences for the commercial chemical sector as well as public health and environmental protection. Accordingly, the Agency wrote the rules in consideration of the many public comments on the proposed actions.

Both final rules were published in the July 20, 2017, Federal Register (FR).


The first rule meets the EPA’s obligation under TSCA section 6(b)(1) to establish a process for prioritizing chemicals for risk evaluations. The law directs that the Agency develop criteria by which it will identify chemical substances from a list of candidates as either high-priority substances for risk evaluation or low-priority substances for which risk evaluations are not warranted at the time.

The EPA notes that its policy objective in writing the rule is to produce a process that allows identification of chemicals that have the greatest hazard and exposure potential first. The process is not intended to depend on an exact scoring or ranking system. Neither does identification of high-priority chemicals depend wholly on how a specific chemical is used.

“The statute is clear that EPA is to designate the priority of the ‘chemical substance’—not a condition of use for a chemical substance,” says the Agency.

In terms of candidate selection, the EPA notes that the TSCA requires the Agency to give preference to chemical substances listed in the 2014 update of the TSCA Work Plan for Chemical Assessments, which are persistent and bioaccumulative; known human carcinogens; and/or highly toxic. The statute further requires that the Agency draw at least 50 percent of its candidates form the Work Plan. Apart from this statutory preference, TSCA does not specifically limit how the EPA must ultimately select a chemical substance to put into the prioritization process.

In response to requests from stakeholders, the EPA’s final rule includes a general objective for designating candidate chemicals as low-priority for risk evaluations consistent with the statutory definition for low-priority substances—“a chemical substance that EPA concludes, based on information sufficient to establish, without consideration of costs or other non-risk factors, does not meet the standard for a high-priority substance.”

Also, in line with TSCA, the prioritization process will last between 9 and 12 months. The process officially begins when the EPA publishes a notice in the FR identifying a chemical substance for prioritization. Publication in the FR starts a 90-day public comment period.

Risk Evaluation

The second rule is the EPA’s response to TSCA section 6(b)(4). That section directs the Agency to establish a process to conduct risk evaluations to “determine whether a chemical substance presents an unreasonable risk of injury to health or the environment, without consideration of costs or other non-risk factors, including an unreasonable risk to a potentially exposed or susceptible subpopulation identified as relevant to the risk evaluation by the Administrator under the conditions of use.”

TSCA also enumerates the deadlines and minimum requirements applicable to risk evaluation process, including provisions that direct which chemical substances must undergo evaluation, the development of criteria for manufacturer-requested evaluations, the minimum components of an Agency risk evaluation, and the timelines for public comment and completion of the risk evaluation. Further, the EPA must undertake the evaluations in a manner consistent with the best available science and make decisions based on the weight of evidence. Each of these elements is addressed in the final rule.

Other requirements that TSCA specifies must be included in the evaluation process and which are covered in the rule include the use of a specific framework to evaluate metals and metal compounds, and a provision to reduce testing on vertebrate animals.

The rule also includes several measures the EPA has added to the TSCA requirements, including adding direct references in the final rule to acknowledge the Agency’s commitment to implementing the best available science and weight of the scientific evidence provisions in TSCA; codifying the Agency’s commitment to interagency collaboration; allowing manufacturers to limit their requests for EPA-conducted risk evaluations to one or more specified conditions of use; and allowing for risk determinations to be made on individual conditions of use or categories of conditions of use at any time once the final scope (which specifies the conditions of use that EPA expects to consider in the risk evaluation) is published.