November 29, 2018

EPA Releases Working Approach for Identifying Potential Candidate Chemicals for Prioritization under TSCA

Lynn L. Bergeson

On September 28, 2018, the US Environmental Protection Agency (EPA) released the general approaches that the Office of Pollution Prevention and Toxics (OPPT) is considering using to identify potential candidate chemicals for prioritization under the Toxic Substances Control Act (TSCA) ( The document, A Working Approach for Identifying Potential Candidate Chemicals for Prioritization (, explains EPA’s thinking regarding a near-term approach for identifying potential chemicals for prioritization, the initial step in evaluating the safety of existing chemicals under TSCA. The approach document also includes a longer-term risk-based strategy for managing the larger TSCA chemical landscape that, according to the portion of the TSCA Chemical Substance Inventory (Inventory) that includes the substances designated as active (TSCA Active Inventory), is expected to include over 38,000 chemicals reported as “active” under the TSCA Inventory Notification (Active-Inactive) Requirements final rule. 82 Fed. Reg. 37,520 (Aug. 11, 2017).

EPA’s Approach Document

The approach document lays out EPA’s near-term approach for identifying potential chemicals for prioritization, the initial step in evaluating the safety of existing chemicals under TSCA. The approach reflects public input received at a December 2017 meeting and through the public docket. EPA also published a summary of public comments (

EPA is also considering a longer-term approach to bin the remaining chemicals (those not included on the 2014 TSCA Work Plan) listed on the TSCA Active Inventory. EPA currently expects to use an approach that integrates available information from both new approach methods (NAM) and traditional approaches, covering the domains of hazard, exposure, persistence, and bioaccumulation for human and ecological domains, to group chemicals based on information availability and hazard and exposure potential. The term “NAM” was introduced previously by EPA to cover any in vitro, in silico, or in chemico techniques used to provide data or information as an alternative to animal testing ( Each approach is discussed below.

Near-Term Approach for Identifying Potential Candidate Chemicals for High-Priority Designation

EPA’s working approach is to look primarily to the 2014 TSCA Work Plan for high-priority potential candidates, as TSCA requires that at least 50 percent of the chemicals undergoing risk evaluation as of December 2019 must come from the 2014 TSCA Work Plan. EPA generally intends to consider three factors for selecting potential chemicals for prioritization. First, EPA expects to consider its overarching priorities. This may include, but is not limited to, a chemical or group of chemicals that are priorities for EPA, including chemicals that other EPA program offices have deemed a priority for their program and suitable for current prioritization. EPA acknowledges that active chemicals not listed on the 2014 TSCA Work Plan may also be selected as candidates for prioritization in cases where other federal agencies, the general public, or the EPA administrator have identified these chemicals as particularly suitable. In such cases, EPA will open dockets for all potential candidate chemicals not listed on the 2014 TSCA Work Plan.

Second, EPA intends to consider the quantity and quality of information in a step-wise approach to ensure responsible and timely completion of the process when identifying potential candidate chemicals for prioritization. The approach is intended to screen out information-deficient candidate chemicals that would hinder its ability to perform scientifically sound risk evaluations from the initial selection of the 20 high-priority and the 20 low-priority candidates. EPA notes that the scientific underpinnings of a risk evaluation need to be strong enough to support a risk evaluation determination and inform potential future risk management activities in a way that allows EPA to meet the tight TSCA deadlines for these actions.

Third, EPA will be mindful of its workload and resource constraints, given the statutory deadlines and other requirements. Once a chemical is designated high priority for risk evaluation, the maximum 3.5-year statutory deadline for completing the risk evaluation begins with no opportunity for interruption or further extension. To address workload issues, EPA states that it could use diverse approaches to consider current expertise or facilitate the analysis of candidate chemicals. EPA could consider selecting a category of chemicals for prioritization. As stated in the July 20, 2017, Procedures for Prioritization of Chemicals for Risk Evaluation final rule, “TSCA section 26 provides EPA with authority to take action on categories of chemical substances.” 82 Fed. Reg. 33,753.

Near-Term Approach for Identifying Potential Candidate Chemicals for Low-Priority Designation

EPA must also designate 20 low-priority chemical substances by December 2019. EPA states that it intends to select candidates that appear to be most suitable for low-priority designation. According to EPA, the most suitable candidates “are those likely to be favored by the considerations in the act (Section 6(b)(1)(A)) [and the regulations at 40 C.F.R. 702.5].” In identifying potential candidates for low-priority chemical designation, EPA will use the best available science, consistent with TSCA section 26(h). EPA may identify substances from multiple sources, including one or more of the following chemical information resources: EPA’s Safer Chemical Ingredients List; EPA’s Chemical Assessment Management Program; and the Organization for Economic and Cooperation Development Screening Information Data Sets assessment documents.

Proposed Longer-Term Approach

The approach document presents a proposed longer-term, risk-based approach that EPA is considering to “bin” chemicals on the TSCA Active Inventory, meaning that EPA would loosely group chemicals on the Inventory into pools that could inform potential prioritization based on risk-based data and information availability. The approach document is intended to begin a public discussion, beginning in late 2018, regarding the implementation of this longer-term approach. EPA will open a docket to accept initial comment on this longer-term approach that will inform expansion of this approach and proof of concept. When complete, the binning approach will help inform which chemicals EPA may choose for prioritization.

The binning scores included in this approach will incorporate human hazard relative to exposure, ecological hazard, genotoxicity, persistence, and bioaccumulation, further building upon prioritization approaches used in the TSCA 2012 Work Plan process and the objectives identified for integrating NAMs in the Canadian Chemicals Management Plan. Consistent with stakeholder feedback, this approach integrates NAMs to fill gaps when traditional testing data are not available. Through the binning approach, EPA also plans to apply US and international data sources for hazard and exposure information and incorporate cutting-edge tools developed by OPPT and especially the EPA’s Office of Research and Development in areas such as human and environmental toxicity predictions, exposure estimations, human hazard-to-exposure ratios, and predictions of persistence and bioaccumulation. Estimates concerning susceptible human subpopulations will be included but initially will be limited to the potential for exposure to children. The document outlines an iterative approach to improve and strengthen future binning efforts by applying the experience gained and through the development of updated and improved tools.

Next Steps

In addition to soliciting comment, EPA will convene a public meeting in early 2019. EPA will also open 73 chemical-specific public dockets, one for each of the remaining chemicals on the 2014 TSCA Work Plan, as well as a general docket for the public to suggest additional chemicals that are not on the Work Plan. With these latter two actions, EPA will provide the public an opportunity to submit use, hazard, and exposure information on these chemicals. EPA states that it will use these data to inform TSCA prioritization and risk evaluation for these chemicals. These dockets will be open until December 1, 2019.

Lynn L. Bergeson

Published: November 29, 2018

Lynn L. Bergeson is managing partner of Bergeson & Campbell, P.C. (B&C®), a Washington, D.C., law firm focusing on conventional, nanoscale, and biobased industrial, agricultural, and specialty chemical product regulation and approval matters, and chemical product litigation. She is President of The Acta Group, L.L.C., and Managing Director of The Acta Group EU, Ltd, with offices in Washington, D.C., and Manchester, UK.