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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. - PowerPoint PPT Presentation
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Can USEPA-RAGS risk assessment methodology be applied to the Workplace?
Michael J. Sullivan, Ph.D., CIH, REACalifornia 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
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
Contact Information
Michael J. Sullivan, Ph.D., CIH, READepartment of Environmental and
Occupational HealthCalifornia State University at Northridge18111 Nordhoff StreetNorthridge, CA [email protected]