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

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 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

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 worker 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 Worker Conc. (RBWC)

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/

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 (706 total chemicals on EPA RSL list)

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 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

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

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

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