Advancing the Framework for Assessing Causality of Health and Welfare Effects to Inform National Ambient Air Quality Standard Reviews (2022) / Chapter Skim
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5 Evidence Synthesis in Integrated Science Assessments
5 Evidence Synthesis in Integrated Science Assessments
Pages 47-56
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From page 47... ...
Descriptions of procedures developed and implemented since the publication of the Preamble are also provided. CURRENT APPROACH TO EVIDENCE SYNTHESIS AND INTEGRATION FOR HEALTH EFFECTS Section 5 of the Preamble is titled "Evaluation, Synthesis, and Integration of Evidence across Disciplines and Development of Scientific Conclusions and Causal Determinations" (EPA, 2015a)
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From page 48... ...
In much more detailed Table 1-2 all the causal conclusions are listed with the reasoning behind them. Quoting to give an example of how these conclusions are presented, the section of this table on "cancer and long-term PM2.5 exposure" includes the following causal determination: Primarily positive associations from multiple epidemiologic studies reporting increases in the risk of lung cancer incidence and mortality.
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From page 49... ...
. The epidemiologic studies were critiqued as commonly lacking consideration of co-pollutant confounding, but the positive associations they found were assessed to be consistent with the animal toxicology results.
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From page 50... ...
The methods rely on three types of studies (as in the PM ISA) : controlled human exposure studies, epidemiology, and animal toxicology, the latter being particularly cited to justify the "biological plausibility" part of the assessment.
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From page 51... ...
and was "considered" for the 2020 ozone ISA, but was excluded from that ISA during the full text screening process for reasons that aren't readily accessible in HERO or the ISA. CURRENT APPROACH TO EVIDENCE SYNTHESIS AND INTEGRATION FOR WELFARE EFFECTS The Preamble's causal determination framework uses modified Bradford Hill aspects of association (Hill, 1965)
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From page 52... ...
Atmospheric chemistry and transport models, coupled atmospheric chemistry-climate models and coupled atmosphere-land-water process models contribute important evidence for causal determinations for effects of criteria pollutants on ecosystems, visibility, radiative forcing, and climate. INTEGRATION AND SYNTHESIS EXAMPLES FOR WELFARE FROM THE 2020 OZONE ISA For ecological effects in the 2020 ozone ISA, causal determinations are presented for 12 major outcome categories (EPA, 2020a, p.
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From page 53... ...
The ISA also cites other observational studies that demonstrated the co-occurrence of tree mortality with elevated ozone but were more limited in their ability to rule out other contributing factors, as well as fumigation experiments that found increased mortality in sensitive tree genotypes. Finding that observations of increased tree mortality are consistent with well-established mechanisms explaining ozone phytotoxicity, the ISA concludes that ozone is likely to be causal for this endpoint (EPA, 2020a)
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From page 54... ...
These included source emissions measurements, atmospheric deposition estimates, empirical measurements of critical loads, models used to estimate CLs, and uncertainties in the aquatic acidification index that EPA developed for the 2008 NOx-SOx ISA (EPA, 2008c)
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From page 55... ...
Given the broad range of welfare effects and the many different study types used to assess them, it may be difficult to develop similar quality criteria tables for evaluating welfare studies. However, similar scientific considerations might logically apply to evaluating the strength of causal inference from various types of welfare studies and could lead to future development of similar study quality criteria for welfare effects studies.
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From page 56... ...
Information from HERO and data about concentrations, study design and results are reported in the appendices to the ISA. Additional detail on study quality evaluation was provided for the most "policy-relevant" studies (those associated with "causal" or "likely causal" determinations or supporting changes in prior causal categories)
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