Prioritizing Existing Chemicals for Risk Evaluation
Prioritization is the initial step in a new process of evaluating the safety of existing chemicals under the Toxic Substances Control Act (TSCA), and is codified in a final Chemical Prioritization Process rule. The purpose of prioritization is to designate a chemical substance as either High-Priority for further risk evaluation, or Low-Priority for which risk evaluation is not warranted at the time. By December 22, 2019, EPA must have designated at least 20 chemical substances as High-Priority and 20 chemical substances as Low-Priority. TSCA further requires that upon completion of a risk evaluation (other than those requested by a manufacturer), EPA must designate at least one additional High-Priority chemical to take its place, thus ensuring that the EPA’s risk evaluation queue always remains full. Prioritization is a priority-setting step. High-Priority designations are not indications of risk and Low-Priority designations are not indications of safety.
The following graphic provides an overview of EPA’s chemical prioritization process.
Learn more about the stages of EPA’s chemical prioritization process:
- Candidate selection
- Screening review
- Proposed designation
- Final designation
- Revision of designation
The pre-prioritization provisions in EPA’s proposed rule were intended to convey expected activities before the Agency would initiate prioritization (e.g., potential candidate identification, information gathering/review, etc.). Based on public comments received, EPA has determined not to finalize these provisions without further discussions with interested stakeholders. The Agency will promptly initiate an additional stakeholder process, to include an additional public comment opportunity addressing EPA approaches for identifying potential candidates for prioritization. EPA is fully committed to further dialogue on best practices for these activities, and to carrying out these activities in a transparent, science based manner, to ensure successful implementation of the prioritization and risk evaluation processes. EPA engaged the public on this matter at a public meeting on Approaches for Identifying Potential Candidates for Prioritization for Risk Evaluation held on December 11, 2017. Learn more. In the interim, the Agency fully expects to move forward with prioritizing chemicals in accordance with the procedures of the final rule.
In identifying candidates for the prioritization process, TSCA requires that 50% of all High-Priority designations be drawn from 2014 Update of the TSCA Work Plan and that EPA also give preference to Work Plan chemicals with the following characteristics:
- Persistence and bioaccumulation scores of three;
- Known human carcinogens; or
- High acute or chronic toxicity.
Aside from these statutory preferences and requirements, EPA has discretion to determine which chemicals to prioritize. EPA expects to engage the public in the Fall of 2017 to discuss best practices for candidate selection and information gathering.
At the initiation step, EPA will formally announce a chemical substance the Agency plans to put through the prioritization process in a Federal Register Notice and give the public a 90-day comment period to submit relevant information. Initiation formally begins the prioritization process, and starts a nine to 12-month statutory timeframe during which the Agency must designate the chemical substance as either High- or Low-Priority.
To support a proposed priority designation, EPA will screen the chemical substance under its conditions of use against certain criteria specified in TSCA section 6(b)(1)(A) by reviewing the reasonably available information with respect to:
- the hazard and exposure potential of the chemical substance;
- persistence and bioaccumulation;
- potentially exposed or susceptible subpopulations;
- storage near significant sources of drinking water;
- the conditions of use or significant changes in the conditions of use of the chemical substance; and
- the volume or significant changes in the volume of the chemical substance manufactured or processed.
“Conditions of use” is a new term in TSCA that means “the circumstances, as determined by the Administrator, under which a chemical substance is intended, known, or reasonably foreseen to be manufactured, processed, distributed in commerce, used or disposed of.” For purposes of prioritization, the Administrator may determine that certain activities fall outside the definition of “conditions of use.”
Additionally, during the Risk Evaluation scoping process, EPA will undergo a second process to identify the “conditions of use” that the Agency expects to consider during the evaluation. The conditions of use considered during the risk evaluation process may be the same or narrower from those identified during the prioritization process. Learn more about the conditions of use through the prioritization and risk evaluation processes.
At the Proposed Designation step, EPA will:
- Propose to designate a chemical substance as either a High-Priority Substance or a Low-Priority Substance;
- Publish the proposed designation and the information, analysis, and basis used to make the designation; and
- Take public comment on the proposed designation and supporting materials for 90 days.
The standards for designating chemicals as High- or Low-Priority Substances are as follows:
- High-Priority Substance – “a chemical substance that the Administrator concludes, without consideration of costs or other nonrisk factors, may present an unreasonable risk of injury to health or the environment because of a potential hazard and a potential route of exposure under the conditions of use, including an unreasonable risk to potentially exposed or susceptible subpopulations identified as relevant by the Administrator”
- Low-Priority Substance – “if the Administrator concludes, based on information sufficient to establish, without consideration of costs or other nonrisk factors, that such substance does not meet the [High-Priority] standard”
After considering public comments received on a chemical’s proposed designation, the Final Designation step requires EPA to:
- Finalize a High-Priority Substance designation and immediately initiate a risk evaluation; or
- Finalize a Low-Priority Substance designation determining that risk evaluation is not warranted at the time.
EPA’s final priority designation will be published in the Federal Register, along with the information analysis and basis used to support the designation.
EPA may revise the designation of a Low-Priority Substance to a High-Priority Substance based on information available to the Administrator. The process for revising such a designation involves restarting the prioritization process, including re-initiating, re-proposing and re-finalizing a designation, and would necessarily provide the same opportunities for public comment.