Systematic Review for TSCA Risk Evaluations

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On May 31, 2018 EPA released  Application of Systematic Review in TSCA Risk Evaluations.  The document presents a detailed description of EPA’s approach to the Risk Evaluations required by the Lautenberg amendments to TSCA.

The announcement by the Office of Pollution Prevention and Toxics (OPPT) explains that “[it] will guide EPA’s selection and review of studies in addition to providing the public with continued transparency regarding how the Agency plans to evaluate scientific information.”  In the document OPPT explains that the Agency intends to apply systematic review principles in the development of the risk evaluations required by the amended statute. The Application of Systematic Review in TSCA Risk Evaluations will serve as internal guidance for this process.  The document describes OPPT’s plan for identifying, evaluating and integrating evidence for the TSCA risk evaluation process.

The document includes chapters on scoping and problem formulation, integration of systematic review principles into TSCA risk evaluations, and appendices on strategy for assessing the quality of data supporting TSCA risk evaluations and data quality criteria for each of the categories of information considered in the evaluation (e.g., physical/chemical property data, occupational exposure and release data).  The Agency notes that this document is not necessarily applicable to risk assessments developed to support other EPA’s statutes or programs.  EPA invites the public to provide input on this document at www.regulations.gov, docket# EPA-HQ-OPPT-2018-0210.

For the risk evaluations, OPPT will first conduct scoping and problem formulation to develop an analytical framework.   Problem formulation will describe the exposure pathways, receptors and health endpoints that OPPT expects to consider in the risk evaluations.

The Agency will use “systematic review“ for problem formulation and the other stages of the risk evaluation process.  The Application of Systematic Review in TSCA Risk Evaluations explains that the risk evaluation process will rely on the National Academy of Sciences, Institute of Medicine’s definition of systematic review:  “a scientific investigation that focuses on a specific question and uses explicit, pre-specified scientific methods to identify, select, assess, and summarize the findings of similar but separate studies.”  OPPT reports that key elements of systematic review include:

  • A clearly stated set of objectives defining the research question,
  • Developing a protocol that describes the specific criteria and approaches that will be used throughout the process,
  • Applying the search strategy in a literature search,
  • Selecting the relevant papers using predefined criteria,
  • Assessing the quality of the studies using predefined criteria,
  • Analyzing and synthesizing the data using the predefined methodology, and
  • Interpreting the results and presenting a summary of findings.

Following problem formulation, OPPT will develop a protocol to specify the criteria, methods for data collection, data evaluation and data integration.

Data will be collected under a defined literature search strategy designed to collect information to evaluate the full life cycle of the chemical substance including exposure, human health hazard, and environmental hazard.  OPPT will use a comprehensive chemical-specific literature search of the open literature to identify relevant data.  OPPT will also use data that are submitted by the public and peer reviewers.  In addition, OPPT will search its internal databases for relevant data submitted under TSCA.  The Agency notes that data submitted under TSCA will be used in the risk evaluation whether or not they are claimed as confidential business information (CBI).  However, CBI data will be used in a manner that protects the confidentiality of the information.

Factors for inclusion in the evaluation include whether the data contain information on: 

  • Environmental fate, transport, partitioning and degradation behavior across environmental media of interest,
  • Environmental exposure of ecological receptors to the chemical substance and/or its degradation products and metabolites,
  • Environmental exposure of human receptors to the substance and/or its degradation products and metabolites,
  • Scenarios resulting in releases of the substance into the environment that would expose ecological or human receptors,
  • Quantitative estimates of worker exposures and of environmental releases from occupational settings for the substance, and
  • Human health and environmental hazards.

OPPT explains that the evaluation stage will assess the quality of individual studies.   For this process the Agency will use the criteria identified in the data quality criteria appendices to the Application of Systematic Review in TSCA Risk Evaluations.  The appendices specify criteria for evaluating data on:

  • Physical and chemical properties,
  • Occupational exposure and release,
  • Fate,
  • Consumer, general population, and environmental exposure,
  • Ecological hazards,
  • Animal and in vitro toxicity, and
  • Epidemiology.

The data will then be integrated to evaluate and synthesize multiple evidence streams.  Data integration includes analysis and synthesis of the evidence and development of weight of evidence conclusions.  As part of this process OPPT will document any underlying assumptions that are used to support the risk evaluation.

TSCA requires that EPA make decisions about these data based on the weight of the scientific evidence.  OPPT reports that under TSCA, the weight of the scientific evidence is defined as “a systematic review method, applied in a manner suited to the nature of the evidence or decision, that uses a pre-established protocol to comprehensively, objectively, transparently, and consistently identify and evaluate each stream of evidence, including strengths, limitations, and relevance of each study and to integrate evidence as necessary and appropriate based upon strengths, limitations, and relevance.”   This approach presents the significant issues, strengths, and limitations of the data and the uncertainties that require consideration, in addition to highlighting the major points of interpretation.

OPPT explains that the last step of the systematic review process will be to develop a summary of findings.  The findings summarize the evidence, describe the methods used to weigh evidence, and articulate the basis for the conclusion(s), recommendation(s), and any uncertainties.  Both exposure assessment and hazard assessment will be discussed.