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

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What Can We Use? OELs PELs Protecting The Worker Precautionary Principle USEPA RAGS HRA

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

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

PEL-Setting Process • Over 400 OSHA PELs • Both toxicology and epidemiology information considered in weight-of-evidence process • Process weighted towards use of worker epidemiology data

USEPA Risk Assessment Process Hazard x Exposure = Risk

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

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

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

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)

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 workplace conc. (RBWC)

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)

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 Workplace Conc. (RBWC)

USEPA Risk Assessment Process • USEPA has published risk-based concentrations (706 chemicals): Regional Screening Levels – RSLs • Residential soil • Residential air • Residential water • Industrial soil • Industrial air http://www.epa.gov/region9/superfund/prg/

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

USEPA Risk Assessment Process • USEPA RSLs (306) • 127 for carcinogenic chemicals • 134 for non-carcinogenic chemicals • 45 for both C and NC chemicals

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

PEL Process vs. USEPA Process • Comparisons of PELs vs. RSLs • 120 chemicals with both PELs and RSLs • 120 PELs higher than RSLs (C + NC) • Additional 290 PELs without RSLs • Additional 186 RSLs without PELs

PEL Process vs. USEPA Process • Comparisons of PELs vs. RSLs • Differences range from 2 x 100 to 2 x 107 • Average difference = 3 x 105 • Average difference = 4 x 104 (top 3 removed) • Overall: a 1000-fold adjustment needed in RSLs to be roughly comparable

PEL Process vs. USEPA Process • Comparisons of PELs vs. RSLs for Carcinogenic Chemicals • All PELs are higher than RSLs • Difference ranges from 2 x 102 to 5 x 105 • Average difference 9 x 104 • A 10,000-fold adjustment needed in RSLs to be roughly comparable

PEL Process vs. USEPA Process • Comparisons of PELs vs. RSLs for Non-Carcinogenic Chemicals • All PELs are higher than RSLs • Difference ranges from 2 x 102 to 2 x 105 • Average difference is 5 x 103 • A 100-fold adjustment needed in RSLs to be roughly comparable

PEL Process vs. USEPA Process • Comparisons of PELs vs. RSLs • For carcinogenic chemicals, PELs much larger than RSLs • Adjustments of 10,000 or 100 needed for carcinogenic or non-carcinogenic chemicals • A straight-use of the RSLs would not be a good substitute for chemicals without PELs

PEL Process vs. USEPA Process • Comparisons of Selected PELs vs. RSLs

PEL Process vs. USEPA Process • Comparisons of Selected PELs vs. RSLs-recc

Recommendation • The PEL process is appropriate for protecting workers • Use adjusted USEPA RSLs (USEPA process) for new chemicals for new chemicals without PEL or appropriate OEL • Use the PEL process to approve or replace any USEPA RSLs with new PELs

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

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

Can USEPA-RAGS Risk Assessment Methodology be Applied to the Workplace?