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Evaluating Cumulative Impacts: The Value of Epidemiology

Evaluating Cumulative Impacts: The Value of Epidemiology. Jonathan Levy Associate Professor of Environmental Health and Risk Assessment, Harvard School of Public Health CHE Partnership Call Evaluating the Impact of Cumulative Stressors on Health April 19, 2010.

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Evaluating Cumulative Impacts: The Value of Epidemiology

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  1. Evaluating Cumulative Impacts: The Value of Epidemiology Jonathan Levy Associate Professor of Environmental Health and Risk Assessment, Harvard School of Public Health CHE Partnership Call Evaluating the Impact of Cumulative Stressors on Health April 19, 2010

  2. Dose-response relationship is dependent on heterogeneity in background exposure, biological susceptibility important to consider all relevant stressors to which people are exposed NRC, 2009

  3. Example: Joint effect of air pollution and exposure to violence on asthma development Clougherty et al., 2007

  4. Science and Decisions conclusions on cumulative risk • NRC committee applauded EPA’s move toward a broader definition, making risk assessment more informative and relevant to decisions and stakeholders. • However, in practice, EPA risk assessments often fall short of what is possible and supported by agency guidelines. • Little consideration of nonchemical stressors, vulnerability, and background risk factors

  5. The role of epidemiology • Most non-chemical stressors (e.g., access to health care, SES) cannot be evaluated in animal studies • In spite of this, there is no guidance for using epidemiology in the EPA Framework for Cumulative Risk Assessment, no mention of epidemiology in any EPA pesticide cumulative risk assessments

  6. Problemformulation/ planning and scoping Selection of epidemiological studies Development of dose-response (D-R) functions • Statistically significant dose-response function? • Biases anticipated and reasonably quantifiable? • Confounding limited unless stressors that cannot be separated jointly considered in risk management? Risk managementobjectives Components Health outcomes and populationsof concern Whole mixture Characterize relative exposures and population vulnerability Characterize individual D-R functions, interactions, population vulnerability Chemicaland non-chemical stressors under consideration (primary and secondary) Adjust D-R functions to address vulnerability, interactions, effect modification Mixture of concern or sufficiently similar Similar mixture, different vulnerability Similar vulnerability, different mixture Different vulnerability, different mixture Adjust D-R function using evidence about components Use D-R function directly Adjust D-R function using related evidence or defaults Combine D-R functions across studies using meta-regression when possible Levy, 2008

  7. Wason et al., 2010

  8. Conclusions • Cumulative risk assessment/impact assessment can be a key component of environmental decision-making, but needs to better capture non-chemical stressors • Direct epidemiological evidence may be impractical in many settings, but epidemiological insight can be leveraged, and non-chemical stressors can be considered through other risk modeling mechanisms

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