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Review of DOD's Approach to Deriving an Occupational Exposure Level for Trichloroethylene (2019) / Chapter Skim
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Summary
Pages 1-5

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From page 1...
... Determine if the process in deriving an OEL for TCE, including the WOE approach to determine relevance of controlled laboratory studies and overall approach corroborating alternative lines of evidence, is scientifically sound. Determine if the derived OEL value is supported by the toxicity information and has followed the WOE approach outlined in the report and provide a summary opinion of the approach and the scientific support for the derivation of the OEL.
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From page 2...
... This puts the agency in a position of having to develop, document, and defend a different approach, which is particularly difficult when applied to a chemical with a large and controversial database, such as TCE. In contrast, DOD's dose-response techniques reflected best practices with respect to validating a PBPK model, evaluating dose-response relationships, and using Bayesian approaches to inform uncertainty adjustments.
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From page 3...
... Most occupational and environmental exposure guidelines are supported by the conventional approach of performing a narrative review, but systematic reviews have started to be adopted for performing hazard assessment for the purposes of public health protection. Animal, human, and mechanistic evidence are typically evaluated separately, and then integrated to make a final hazard determination.
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From page 4...
... Most significantly, the quantitative scores are contrary to standard systematic review practices, as numerical scores falsely imply a relationship between scores and effect or association, along with several other critical limitations. The committee recommends that DOD abandon the use of this study applicability tool in favor of established tools to assess risk of bias of animal and human studies.
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From page 5...
... physiology, if TCE exposures occur in workplace scenarios where ventilation rate and cardiac output would be elevated. DOD should also consider using the PBPK model to evaluate the oral data available on all target end points, rather than just the end points with insufficient inhalation data, to take advantage of the robust database on TCE.
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Key Terms

  • hazard identification
  • study applicability
  • occupational exposure
  • narrative review
  • pbpk model

  • applicability tool
  • hazard assessment
  • uncertainty factors
  • study quality
  • animal data

  • individual studies
  • woe approach
  • based pharmacokinetic
  • epa assessment
  • cancer risk

  • exposure level
  • exposure guidelines
  • physiologically based
  • review methods
  • assess risk

  • evaluation techniques
  • bayesian approaches
  • robust database
  • using systematic
  • identification hazard

  • systematic reviews
  • support hazard
  • standard systematic
  • established systematic
  • relevant exposure


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