Prioritization and Risk Assessment Procedures under TSCA

The Toxic Substances Control Act (TSCA) is the cornerstone of chemical regulation in the United States, providing a framework to assess and manage the potential risks posed by various chemicals. Within the TSCA framework, the prioritization and risk assessment procedures play a pivotal role in ensuring the safety of chemicals used in commerce.

Understanding the TSCA Prioritization Process

In the EPA's current chemical procedure under TSCA, the risk evaluation process follows a systematic approach that aims to assess chemicals thoroughly. This approach places risk evaluation after prioritization but before risk management, creating a structured and science-driven methodology to ensure chemical safety.

The primary goal of the risk assessment is to determine whether a chemical poses an unreasonable danger to human health or the environment when used as directed. This assessment also considers the potential undue risks to any relevant subpopulation that may be exposed or vulnerable to the chemical's effects.

To achieve this goal, the EPA follows a set of essential steps:

• Determining Risk and Exposure

The initial step involves assessing the risk associated with a specific chemical and understanding its potential exposure pathways. This critical analysis is fundamental to identifying the scope of the potential problem and directing further investigation.

• Excluding Non-Risk Factors

In the risk assessment, the EPA does not take into account costs or other non-risk-related factors. This approach ensures that the evaluation remains focused on the scientific aspects of chemical safety, minimizing external influences on the process.

• Utilizing Scientific Data and Methods

The risk assessment process relies heavily on scientific data and methodologies. The EPA adheres to TSCA's requirements for the best available science, ensuring that decisions are made based on a solid foundation of evidence and research.

• Relying on Scientific Evidence

Central to the risk assessment process is the reliance on the strength of scientific evidence. This data-driven approach ensures that the decisions made regarding a chemical's safety are rooted in rigorous scientific research and analysis.

The TSCA Prioritization and Risk Assessment in Action

The amended TSCA requires the U.S. Environmental Protection Agency (EPA) to undertake a prioritization process for a selection of 40 chosen chemicals. This significant undertaking is a demonstration of the EPA's commitment to evaluating and managing chemicals effectively to protect human health and the environment.

The notice for this prioritization process was published on March 20, 2019, marking a critical milestone in chemical safety regulation. According to TSCA, the EPA is mandated to regularly review chemicals that are currently on the market to ensure they meet the necessary safety criteria.

Out of the 40 chemicals selected, 20 have been identified as "High Priority Substances." These substances are subjected to a rigorous three-year risk assessment procedure. This assessment aims to determine whether these chemicals pose risks to both human health and the environment.

Conversely, the remaining twenty substances have been categorized as "Low Priority Substances" for risk assessment. This classification reflects the EPA's strategic allocation of resources, focusing more intensive scrutiny on chemicals of higher concern while ensuring that chemicals of lower potential risk are not overlooked.

The 20 candidates for High Priority Designations

• Seven chlorinated solvents, five of them relevant for food contact materials (FCM), namely p-dichlorobenzene (CAS 106-46-7), 1,2-dichloroethane (CAS 107-06-2), o-dichlorobenzene (CAS 95-50-1), 1,1,2-trichloroethane (CAS 79-00-5), and 1,2-dichloropropane (CAS 78-87-5);

• Five FCM-relevant phthalates that were also prioritized in the “Hazardous chemicals in plastic packaging” project coordinated by Food Packaging Forum (FPF reported), namely: butyl benzyl phthalate (BBP, CAS 85-68-7), di-ethylhexyl phthalate (DEHP, CAS 117-81-7), dibuty phthalate (DBP, CAS 84-74-2), di-isobutyl phthalate (DiBP, CAS 84-69-5) and dicyclohexyl phthalate (DCP, CAS 84-61-7);

• A phthalate precursor substance, phthalic anhydride (CAS 85-44-9), also used in FCMs. Three halogenated flame retardants, all of which are FCM-relevant: 2,2’,6,6’-tetrabromobisphenol A (TBBPA, CAS 79-94-7), tris(2-chloroethyl) phosphate (TCEP, CAS 115-96-8), and phosphoric acid, triphenyl ester (TPP, CAS 115-86-6);

• Two substances used as chemical intermediates in polymer synthesis, of which 1,3-butadiene (CAS 106-99-0) is widely used in FCM production. Formaldehyde (CAS 50-00-0), which is a chemical intermediate and preservative also used in FCMs among multiple other uses;

• The list of high-priority substances is completed by the synthetic musk 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta [g]-2-benzopyran (HHCB), which has been identified as relevant for food service and food production, as well as its widespread use in personal care and household products.

Ensuring Continuous Evaluation

TSCA further requires that upon the completion of a risk evaluation (other than those initiated by a manufacturer), the EPA must designate at least one additional High-Priority chemical to take its place. This continuous cycle ensures that the EPA's risk evaluation queue always remains full, enhancing the regulatory oversight and protection of human health and the environment.

The Stages of EPA's Chemical Prioritization Process

To understand the TSCA prioritization and risk assessment procedures fully, it's essential to grasp the various stages of this meticulous process: Approach to TSCA Prioritization

• The EPA's first step is to establish an approach to prioritize chemicals. This approach is based on the criteria and procedures outlined in the TSCA amendments.
• The agency considers various factors, including exposure potential, hazard characteristics, and available data, to determine how chemicals should be prioritized. Candidate Selection
• In this stage, the EPA identifies a list of candidate chemicals that may undergo prioritization.

EPA give preference to Work Plan chemicals with the following characteristics:

1. Persistence and bioaccumulation scores of three;
2. Known human carcinogens;
3. High acute or chronic toxicity.

Initiation

• Once the candidates are selected, the EPA formally initiates the prioritization process for those chemicals.
• This initiation involves announcing the start of the process and providing relevant information to the public and stakeholders. Transparency and engagement are fundamental aspects of this stage.

Screening Review

• The screening review is a pivotal step in the process where the EPA evaluates the selected candidates to determine whether they meet the criteria for either "High Priority" or "Low Priority" designation.
• This stage involves collecting and analyzing available information on the chemicals, such as toxicity data and exposure potential, to make informed decisions.

Proposed Designation

• Based on the screening review results, the EPA may propose the designation of a chemical as either "High Priority" or "Low Priority."

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 – 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

Final Designation

• After considering public comments and additional data, the EPA makes a final designation of whether a chemical is "High Priority" or "Low Priority."

• This final designation is published in the Federal Register, marking a crucial milestone in the prioritization process. If a chemical is designated as "High Priority," it proceeds to the next stage, which is the risk evaluation process, emphasizing the importance of public input in shaping regulatory decisions.

Revision of Designation

• In certain cases, the EPA may revise the designation of a chemical based on new information or data that becomes available after the initial designation.
• This flexible approach ensures that the EPA can adapt to emerging information and make changes as necessary to protect the public.

Conclusion: Protecting Human Health and the Environment

In conclusion, the prioritization and risk assessment procedures under TSCA are integral to the EPA's commitment to safeguarding human health and the environment from potentially hazardous chemicals. This structured and science-driven process ensures that chemicals of concern are subject to a comprehensive risk evaluation, while chemicals with lower potential risks receive appropriate attention and regulatory oversight. It's part of the EPA's ongoing efforts to protect the well-being of the public by effectively managing chemical substances in commerce.