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Assessing and Managing Chemicals under TSCA

Risk Evaluations for Existing Chemicals under TSCA

This page provides an overview of how EPA conducts risk evaluations for chemicals under the Toxic Substances Control Act (TSCA), as amended by the Frank R. Lautenberg Chemical Safety for the 21st Century Act, the status of EPA’s ongoing risk evaluations and other assessment-related activities and documents.

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The Risk Evaluation process is the second step, following Prioritization and before Risk Management, in EPA’s existing chemical process under TSCA.  The purpose of risk evaluation is to determine whether a chemical substance presents an unreasonable risk to health or the environment, under the conditions of use, including an unreasonable risk to a relevant potentially exposed or susceptible subpopulation.  As part of this process, EPA must evaluate both hazard and exposure, exclude consideration of costs or other non-risk factors, use scientific information and approaches in a manner that is consistent with the requirements in TSCA for the best available science, and ensure decisions are based on the weight-of-scientific-evidence. 

Read the Risk Evaluation Rule

Risk Evaluation Process and Timeline

The figure below provides an overview of the steps in EPA’s risk evaluation process for existing chemicals.

Chart: Steps for Evaluating Risks

Initiation of the Risk Evaluation

A risk evaluation can be initiated by EPA based on the outcome of Prioritization or initiated by EPA based on acceptance of a manufacturer’s request for a risk evaluation:

  1. EPA-Initiated Risk Evaluations
    With the passage of the Lautenberg Act, EPA was required to select the first 10 chemicals to undergo risk evaluations from the 2014 Update to the TSCA Work Plan. These 10 chemicals were announced on December 16, 2016.

    Read the announcement of the selection of the first ten chemicals.
    Read more about the first ten chemicals evaluated

    Following the first 10 chemicals, EPA will conduct risk evaluations on chemical substances designated as High-Priority Substances through the Prioritization process.
  2. Manufacturer-Requested Risk Evaluations
    Chemicals may be evaluated following EPA’s approval of a manufacturer’s request for a risk evaluation of a chemical they manufacture. The number of chemicals undergoing risk evaluation as the result of such a requests must constitute 25-50% of the total of EPA-initiated risk evaluations, if EPA receives sufficient compliant requests.

Components of a Risk Evaluation

  1. Scope of the Risk Evaluation
    • The scope of a risk evaluation will include the hazards, exposures, conditions of use, and the potentially exposed or susceptible subpopulations the Administrator expects to consider. The scope will also include:
      • A Conceptual Model, which will describe the relationships between the chemical, under the conditions of use, and humans and the environment.
      • An Analysis Plan, which will identify the approaches and methods EPA intends to use to assess exposures and hazards.
    • “Conditions of use” under TSCA means “the circumstances, as determined by the Administrator, under which a chemical substance is intended, known, or reasonably foreseen to be manufactured, processed, distributed in commerce, used or disposed of.” For purposes of prioritization, the Administrator may determine that certain uses fall outside the definition of “conditions of use.” During the risk evaluation scoping process, EPA may decide to narrow the scope of the risk evaluation further, potentially excluding conditions of use that present low risk.
    • Draft Scope
      • A draft scope will be published in the Federal Register no later than three months from the initiation of the risk evaluation process.
    • 45-day public comment period on the draft scope
      • A docket will be opened for no less than 45 days to facilitate public comment on the draft scope.
    • Final Scope
      • A final Scope will be published no later than six months after initiation of the risk evaluation, as required by the law.
  2. Hazard assessment
    • EPA will identify the adverse health or environmental effects caused by exposure to the chemical. Hazards may include, but are not limited to, toxicity with respect to cancer, mutation, reproductive, developmental, respiratory, immune, cardiovascular impacts, and neurological impairments.
  3. Exposure assessment
    • EPA will identify, where relevant, the likely duration, intensity, frequency, and number of exposures to a chemical under the conditions of use. This assessment will also include the nature and types of individuals or populations that are exposed to the chemical.
  4. Risk characterization
    • EPA will integrate and assess the reasonably available information on hazard and exposure and will also include considerations of information quality and alternative interpretations.
  5. Risk determination
    • EPA will make a draft determination as to whether the chemical substance, under the conditions of use, presents an unreasonable risk to health or the environment.
      • Those conditions of use determined to present an unreasonable risk to health or the environment will move immediately into risk management.

Publication of the Risk Evaluation

  • Draft Risk Evaluation
    • A draft scope will be published in the Federal Register.
    • Each draft risk evaluation will be peer reviewed.
  • 60-day public comment period on the draft risk evaluation
    • A docket will be opened for no less than 60 days to facilitate public comment on the draft risk evaluation.
  • Final Risk evaluation
    • A final risk evaluation will be published no later than 3 to 3.5 years after identification of the chemical as a high priority for risk evaluation.

Science Requirements

EPA is required to meet the scientific standards in TSCA for best available science, utilizing a weight-of-scientific-evidence approach when conducting risk evaluations.  The application of these standards will be documented throughout the risk evaluation process and available for public comment. 

EPA’s initial work on systematic review was described in the supplemental files for each TSCA scope document, which included the Strategy for Conducting Literature Searches and the Bibliography for each chemical. Read the Agency’s response to the comments received on these supplemental documents.

Additionally, EPA has released for public comment an Application of Systematic Review in TSCA Risk Evaluations document that will guide the Agency’s selection and review of studies and provide the public with continued transparency regarding how EPA plans to evaluate scientific information. Read and learn how to comment on the systematic review approach.

Learn more about the regulatory requirements for risk evaluation.

First Ten Chemicals for Risk Evaluation

On December 19, 2016, EPA published a list of 10 chemical substances that are the subject of the Agency’s initial chemical risk evaluations, as required by TSCA § 6(b)(2)(A).  As an initial step in the risk evaluation process, in June 2017 EPA published the scope of the risk evaluations to be conducted for the first 10 chemicals, including the hazards, exposures, conditions of use and potentially exposed or susceptible subpopulations that the Agency expects to consider.

After releasing the scope documents, the dockets for each of the first 10 chemicals were open for public comments. Read EPA’s Responses to Public Comments Received on the Scope Documents for the First Ten Chemicals for Risk Evaluation under TSCA. This document addresses cross-cutting public comments received in response to EPA publishing the scope documents.

As an important interim step, in June 2018 EPA published problem formulation documents which refine the scope of the risk evaluations. Read the Federal Register notice announcing the availability of the problem formulation documents. In November 2018, EPA began to release draft risk assessments for the chemicals, beginning with pigment violet 29.

The docket numbers, problem formulations, scope documents and supplemental documents for the 10 chemical substances that EPA initiated the risk evaluation process for in December 2016 can be found here:

Manufacturer-Requested Risk Evaluations

TSCA allows manufacturers of a chemical to request an EPA-conducted risk evaluation on the chemical.  A manufacturer may request a risk evaluation for conditions of use of interest to the manufacturer.  TSCA required EPA to develop the form and manner under which these requests must be made, and the criteria for which EPA will determine whether to grant a request.  The general process and timeline for a manufacturer requested risk evaluation is as follows:

  • Manufacturers must submit a request for a risk evaluation using EPA’s Central Data Exchange (CDX).
    • A request must include the following information: The manufacturer name and contact information; chemical identity; conditions of use of interest; and all information necessary for EPA to conduct the risk evaluation on the conditions of use of interest (e.g., hazard, exposure, potentially exposed or susceptible subpopulations), among other information.
  • Within 15 days of the receipt of a facially compliant request (i.e., appears to include all the necessary information), EPA will notify the public of the receipt of the request.
  • Within 60 days of the receipt of a facially compliant request, EPA will publish the request in the Federal Register, along with any additional information EPA may consider in this risk evaluation and identification of the additional conditions of use EPA believes should be included in the evaluation, and open a docket for no less than a 45-day public comment period to accept comment on the request and the additional conditions of use EPA is considering for inclusion.
  • Within 60 days of the end of the public comment period, EPA will make a decision to grant or deny the manufacturer request. 
  • The risk evaluation will be initiated upon payment of fees as established in the final fees rule.
  • All risk evaluations, whether EPA-initiated or manufacturer-requested, will be conducted in the same manner.

    Read more about this process in the Risk Evaluation Rule

Risk Assessments on Work Plan Chemicals

Prior to the passage of the Lautenberg Act, EPA completed risk assessment activities on some work plan chemicals. While the information in these assessments may not represent the Agency’s current work on these chemicals, the information is available for reference and historical purposes.

See assessments on additional work plan chemicals conducted prior to amended TSCA