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Can USEPA-RAGS risk assessment methodology be applied to the Workplace?

Can USEPA-RAGS risk assessment methodology be applied to the Workplace?. Michael J. Sullivan, Ph.D., CIH, REA California State University at Northridge. Outline. PEL-Setting Process USEPA Risk Assessment Process Comparison of Processes Comparison of Results Recommendation.

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Can USEPA-RAGS risk assessment methodology be applied to the Workplace?

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  1. Can USEPA-RAGS risk assessment methodology be applied to the Workplace? Michael J. Sullivan, Ph.D., CIH, REA California State University at Northridge

  2. Outline • PEL-Setting Process • USEPA Risk Assessment Process • Comparison of Processes • Comparison of Results • Recommendation

  3. PEL-Setting Process • OSHA must propose and promulgate the PEL • Input received from NIOSH in form or Recommended Exposure Level (REL) • Other OELs can be considered

  4. PEL-Setting Process • Over 600 PELs have been promulgated by OSHA • Both toxicology and epidemiology information considered in weight-of-evidence process • Process weighted towards use of worker epidemiology data

  5. USEPA Risk Assessment Process Hazard x Exposure = Risk

  6. USEPA Risk Assessment Process • Over 700 chemicals in USEPA database • Both toxicology and epidemiology information considered in weight-of-evidence process • Process weighted towards use of toxicology data

  7. USEPA Risk Assessment Process • Calculations slightly different for carcinogens vs. non-carcinogens • Based on assumption of non-threshold vs. threshold mechanisms of action

  8. USEPA Risk Assessment Process • Carcinogenic risks is Incremental Lifetime Cancer Risk (ICLR) • Non-carcinogenic risk is Hazard Quotient (HQ)

  9. USEPA Risk Assessment Process • Carcinogens • Hazard = Cancer Slope Factor (CSF) (units = 1/exposure units) • Exposure = Lifetime Average Daily Dose (LADD) (units = exposure units) • Hazard x Exposure = Risk (unitless)

  10. USEPA Risk Assessment Process • Carcinogens • LADD = EPC x Exposure Parameters • EPC = Exposure Point Concentration (e.g., concentration in air – mg/m3) • mg/m3 x exposure parameters x CSF = ILCR • mg/m3 = ILCR/(exposure parameters x CSF) • mg/m3 = Risk-based worker conc. (RBWC)

  11. USEPA Risk Assessment Process • Non-Carcinogens • Hazard = Reference Concentration (RfC) (units = mg/m3) • Exposure = Average Daily Dose (ADD) (units = mg/m3) • 1/Hazard x Exposure = Risk (unitless)

  12. USEPA Risk Assessment Process • Non-Carcinogens • Exposure = EPC x Exposure Parameters • EPC = Exposure Point Concentration (e.g., concentration in air – mg/m3) • mg/m3 x exposure parameters x 1/RfC = HQ • mg/m3 = (HQ x RfC)/exposure parameters • mg/m3 = Risk-based Worker Conc. (RBWC)

  13. USEPA Risk Assessment Process • USEPA has published risk-based concentrations: Regional Screening Levels – RSLs • Residential soil • Residential air • Residential water • Industrial soil • Industrial air http://www.epa.gov/region9/superfund/prg/

  14. USEPA Risk Assessment Process • USEPA Industrial Air RSLs based on: • ILCR = 1 x 10-6 • HQ = 1.0 • Exposure Parameters • 25 years • 250 days/year • 8 hours/day • 70 kg body weight

  15. USEPA Risk Assessment Process • USEPA RSLs (306) • 127 for carcinogenic chemicals • 134 for non-carcinogenic chemicals • 45 for both C and NC chemicals (706 total chemicals on EPA RSL list)

  16. PEL Process vs. USEPA Process • PELs • Require consensus • Enforcable • Weighted towards workplace epidemiology • RSLs • Easy to calculate • Not enforceable • Weighted towards toxicology data

  17. PEL Process vs. USEPA Process • Comparisons of PELs vs. RSLs for Selected Carcinogenic Chemicals • All PELs are higher than RSLs • Difference ranges from 100-fold to 50,000 fold • A 100 to 1,000-fold adjustment needed in RSLs to be roughly comparable

  18. PEL Process vs. USEPA Process • Comparisons of PELs vs. RSLs for Selected Non-Carcinogenic Chemicals • All PELs are higher than RSLs • Difference ranges from 20-fold to 1,500- fold • A 10 to 100-fold adjustment needed in RSLs to be roughly comparable

  19. Recommendation • The PEL process is appropriate for protecting workers • Use adjusted USEPA RSLs (USEPA process) for new chemicals • Use the PEL process to approve or replace any USEPA RSLs with new PELs

  20. Conclusion • The combined use of the PELs and RSLs can effectively protect worker health

  21. Contact Information Michael J. Sullivan, Ph.D., CIH, REA Department of Environmental and Occupational Health California State University at Northridge 18111 Nordhoff Street Northridge, CA 91330 michael.sullivan@csun.edu

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