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EPA Issues TSCA Proposal for Prioritization of Chemicals for Risk Evaluations

On January 17, 2017, the U.S. Environmental Protection Agency (EPA) published a proposal to establish procedures to prioritize chemical risk evaluations.  82 Fed Reg. 4,825. This proposal details the process EPA plans to use to identify “High-Priority” chemical substances and initiate risk evaluations.

“High-Priority” substances are those that 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” with considerations only being made to risk factors, and no considerations to cost. EPA seeks to set a low bar and anticipates that a large number of chemical substances will meet the “High-Priority” standards. Meanwhile, the “Low-Priority” standards are more rigorous, and risk evaluations will not be conducted on these substances.

Comments on the proposal must be received by March 20, 2017.


On June 22, 2016, TSCA was amended by the Frank R. Lautenberg Chemical Safety for the 21st Century Act. Under the original TSCA, EPA administered health and safety reviews for new chemical substances before they entered the marketplace. Chemical substances in existence at the time were “grandfathered” without EPA review. The amendment includes a requirement for the EPA to assess existing chemical substances for health, safety and environmental impact, and manage identified risks. EPA will have to designate chemical substances as “High-priority,” and conduct risk evaluations, or “Low-priority.”. This proposed rule on prioritization is the first step in establishing procedures to conduct risk evaluation under TSCA.

Sections 6(b)(1) through (3) require that EPA provide specificity on this risk-based screening process including “preferences for certain chemical substances that EPA must apply, the procedural steps, definitions of High-Priority Substances and Low-Priority Substances, and screening criteria” in order to make its considerations in designating chemical substances.

Procedures and Timing

EPA anticipates exercising its new authority to meet deadline requirements throughout prioritization and risk evaluations. The collection, reviewing, and incorporation of new information prior to and throughout the prioritization process may include TSCA information collection, testing, and subpoena authority. 

This proposed rule organizes prioritization into four steps: (1) Pre-Prioritization; (2) Initiation; (3) Proposed Designation; and (4) Final Designation. In step one, Pre-Prioritization, EPA proposes to expand its criteria beyond Section 6(b)(2) to narrow the pool of candidates and assist in identifying chemical substances to conduct its risk evaluation screening. There is no statutory limitation on the process to select a chemical substance aside from the requirement that the process be “risk based.” EPA is proposing to conduct these assessments by considering: persistence in bioaccumulation and toxicity; use in children’s products; use in consumer products; detection in human and/or ecological biomonitoring programs; potential of concern for children’s health; high acute and chronic toxicity; probable or known carcinogen; neurotoxicity; or other emerging exposing and hazards to human health or the environment.  The proposal includes a provision to identify chemical substances that present a hazard, where exposure is present under “one or more conditions of use,” but “unreasonable risk” cannot  be determined without further evaluation. While EPA will not be designating uses of chemical substances as “High” or “Low” priority, it will be using prioritization to manage chemical substances themselves; known, intended or reasonably foreseeable uses will be considered in EPA’s analyses. EPA is proposing to include a statement that it is not limiting itself to exclude categories of chemical substances from its purview.

Step two, Initiation, requires EPA to announce a selected candidate chemical substance, and provides the public with a 90-day period to comment and submit information. In the next step, Proposed Designation, EPA will designate the chemical substance as “High-Priority” or “Low-Priority.” The information, analysis, and basis for this designation will be published and the public will have another opportunity to comment for a 90-day period.

In the final step, Final Designation, EPA must finalize the chemical substance’s designation. A risk evaluation will be initiated on a final “High-Priority” chemical substance. But, a “Low-Priority” substance will not require a risk evaluation, unless it is revisited by EPA at a later date. A “Low-Priority” substance can be re-designated “High-Priority” through a process of re-screening; however, a “High-Priority” substance must go through the entire risk evaluation process.

The prioritization process is proposed to last between nine and twelve months. EPA is proposing that this period would begin when a notification that identifies a chemical substance for prioritization and the results of the screening review is published in the Federal Register. The process would be complete when a notice in the Federal Register is published announcing a final priority designation. “High Priority” chemical substance risk evaluations must commence immediately and be completed within three years. Each time a risk evaluation is complete, EPA must designate one additional chemical substance as “High Priority” to take its place.

Further Requirements

Chemical substances listed in the 2014 Update of the TSCA Work Plan for Chemical Assessments that have bioaccumulation scores of 3, and are known human carcinogens with high acute chronic toxicity are given preference in “High Priority” designations. Additionally, 50% of ongoing TSCA risk evaluations must be drawn from the TSCA Work Plan list. All chemical substances on this list must eventually be prioritized.

In order to take into account the “special attributes and behaviors” of metals, EPA is required to use the March 2007 Framework for Metals Risk Assessment of the Office of the Science Advisor when prioritizing and conducting chemical risk evaluations for metals or metal compounds.

All chemical substances on the TCSA Inventory are subject to prioritization, including those designated as “inactive” under the TSCA Inventory Reset. 82 Fed Reg. 4,255.