What to Expect: TSCA Update for Chemical Prioritization
January 16, 2017
At a public stakeholder meeting held December 11, 2017, the U.S. Environmental Protection Agency (EPA) discussed potential approaches to organize and sort the estimated 83,000 Toxic Substances Control Act (TSCA) Inventory chemicals commercially manufactured or imported in the United States before inclusion in the prioritization process. According to current statutory deadlines, EPA must designate at least 20 chemical substances as High-Priority and 20 chemical substances as Low-Priority by the end of 2019. For companies with chemical and product portfolios, it is important to understand how the chemical designations of High- and Low-Priority might affect their inventories.

In the 2012 TSCA Work Plan, updated in 2014, EPA has designated chemicals that scored high in the prioritization screening process, based on their combined hazard, exposure, and persistence and bioaccumulation characteristics, as candidates for the more extensive risk evaluation process over the next several years. TSCA, as amended by the 2016 Lautenberg Chemical Safety Act, requires that at least 50% of the chemicals entering the risk evaluation process be drawn from the 2014 Update to the TSCA Work Plan until that list has been exhausted. Work Plan chemicals with high persistence and bioaccumulation scores, those that are known carcinogens, and those that have known acute or chronic toxicity are to be further prioritized. Aside from these statutory requirements, EPA has discretion to determine which chemicals to prioritize.

EPA Seeks Public Feedback on Chemicals

EPA is now seeking public feedback on systematic approaches for organizing and sorting chemicals before prioritization. The agency’s approach for identifying candidates for “pre-prioritization” could be implemented between June 2018 and March 2019 and will likely consider the following six potential approaches:

  • The 2012/2014 TSCA Work Plan methodology may be applied to screen chemicals using a risk-based approach, based on numerical scoring of hazard, exposure, and persistence and/or bioaccumulation. This methodology would identify high-priority chemicals for risk evaluation and identify those for which more data are needed.
  • A chemical data approach, similar to Canada's Chemical Management Plan (CCMP), may be utilized, in which consideration of persistence, bioaccumulation, toxicity (to humans and ecological receptors), and potential for human exposure are used as criteria to identify chemicals requiring no further regulatory action, those requiring further assessment, or those requiring risk management. The CCMP is currently evolving to integrate streamlined approaches such as ecological risk classification, the threshold of toxicological concern approach, and rapid screening. It also employs periodic evaluation of new chemical information to determine if further action may be warranted.
  • The Safer Chemical Ingredients List may be used to identify low-priority chemicals. This approach would identify chemicals determined by EPA to be among the safest within their functional classes, based on their hazard profile.
  • A functional category approach could be used to sort groups of chemicals with similar functional uses according to their use profiles and potential for exposure. This approach would employ functional use categories defined by Chemical Data Reporting (CDR) and the Organisation for Economic Co-operation and Development (OECD) and data from 2016 CDR, the Toxics Release Inventory, or Consumer Product Safety Commission Product Evaluations to rank functional use groups according to the magnitude and types of potential exposures. For example, Tier 1 functional use categories might be those that are widely used in consumer products with a high likelihood of exposure.
  • Another possible approach would be a functional use approach that would initially group chemicals into functional use groups based on their structure and physicochemical properties and, as a second step, use hazard and exposure data to identify candidates for prioritization within a functional use group.
  • EPA’s Office of Research and Development is developing a methodology along with web-based software tools and underlying databases to identify candidates for prioritization by considering traditional data ( e.g., toxicity test results, exposure monitoring, and persistence/bioaccumulation data) coupled with new types of data (in silico models, high throughput screening, chemical read-across, exposure modeling, etc.).

Regardless of which approach EPA selects, chemical exposure and hazard (human health and ecological) data, as well as persistence and bioaccumulation data, will be needed to adequately prioritize chemicals. Due to the additional data gathering authorization provided under the amended TSCA, EPA is now more likely than in the past to request generation of new data to fill existing data gaps.

How Can Exponent Help?

Exponent’s scientific and regulatory consultants have expertise in new and traditional methods for conducting chemical risk evaluations and designing strategies to address TSCA prioritization. Exponent scientists are well versed in EPA’s Sustainable Futures models, QSAR modeling, read-across strategies, testing design and monitoring, and weight-of-the-evidence-based hazard and risk assessments.

We can help perform relative risk screenings for chemicals in your existing inventories, as well as identify significant data gaps, and design intelligent data gathering programs to cost effectively provide the most critical information. In addition, Exponent’s scientists and materials engineers can assist you in identifying and integrating favorable substitutes for chemicals of potential concern used in your products.