A Proof-of-Concept Case Study Integrating Publicly Available Information to Screen Candidates for Chemical Prioritization

Published July 13, 2021

EPA has released a report titled, “A Proof-of-Concept Case Study Integrating Publicly Available Information to Screen Candidates for Chemical Prioritization under the Toxic Substances Control Act (TSCA)”. This report presents the Public Information Curation and Synthesis (PICS) approach, which integrates publicly available hazard, exposure, persistence, and bioaccumulation information for chemical substances. The approach compares the amount of scientific studies available on a particular chemical versus potential human health and environmental effects found in those studies. This data can be used to help inform the level of effort and resources needed to evaluate a specific substance.

The proof-of-concept case study applied the PICS approach to a subset of the TSCA active inventory to test its efficacy. The results demonstrate that the approach successfully discriminated between potential high- and low-priority candidate substances and identified possible gaps in data. The use of the PICS approach in the proof-of-concept study is part of EPA’s efforts to develop and use alternative test methods and strategies to reduce, refine, or replace vertebrate animal testing.

The PICS approach is not designed to replace the current prioritization process required by TSCA. Rather, this approach is one of the many tools the Agency could use to identify candidates for prioritization and ultimately for risk evaluation. It could also potentially increase the efficiency of identifying potential data gaps in a way that is both transparent and reproducible.

Aspects of the PICS approach could be used by other federal, state, international organizations, and other stakeholder groups to inform chemical prioritization decisions. For example, EPA collaborated with the Minnesota Department of Health (MDH) on a pilot effort based on the PICS approach. MDH’s Health Risk Assessment Unit establishes human health-based risk assessments for contaminants of emerging concern (CEC) in Minnesota waters. The pilot succeeded in developing an automated workflow for exposure screening of drinking water contaminants. Prior to the pilot, MDH’s exposure screening process was predominantly a manual process. The automated workflow that EPA helped develop improved both the reproducibility and speed of the exposure screening, reducing the time required to evaluate a single chemical from days to minutes! These improvements will allow MDH to screen large numbers of chemicals for potential candidates for the CEC regulatory program, and this is a great example of utilizing the PICS approach in other decision-making frameworks.

EPA researchers are continuously refining and improving their data curation and synthesis processes to create a more efficient way of researching chemicals. These improved processes will help EPA and others making decisions about chemicals more efficiently and better protect human health and the environment.

Since the release of the proof-of-concept study, EPA continues to make strides towards using innovative science to review new chemicals before they enter the marketplace. In February 2022, EPA announced a new effort under the Toxic Substances Control Act (TSCA) to modernize the process through a New Chemicals Collaborative Research Program.

 Background: Prioritization is the initial step in the process of evaluating existing chemicals under TSCA and is promulgated  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. 

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 EPA must establish a queue of chemicals prioritized for risk evaluation.  However, high-priority designations are not indications of risk and low-priority designations are not indications of safety.

More information on prioritization can be found at https://www.epa.gov/assessing-and-managing-chemicals-under-tsca/prioritizing-existing-chemicals-risk-evaluation.

For more information about the TSCA Proof-of-Concept join us for the Computational Toxicology Communities of Practice webinar on July 22nd, 2021 at 11AM EST with presenter Dr. Maureen Gwinn. Presentation slides for this webinar will be available after the meeting. Register for the webinar here!