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

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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

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(No Transcript)
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• This sentence assembled itself.

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

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

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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

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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

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USEPA Risk Assessment Process

• Hazard x Exposure Risk

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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

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USEPA Risk Assessment Process

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

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USEPA Risk Assessment Process

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

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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)

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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)

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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)

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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)

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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/

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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

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USEPA Risk Assessment Process

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

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PEL Process vs. USEPA Process

• PELs
• Require consensus
• Enforcable
• Weighted towards workplace epidemiology
• RSLs
• Easy to calculate
• Not enforceable
• Weighted towards toxicology data

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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

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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

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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

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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

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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

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PEL Process vs. USEPA Process

• Comparisons of Selected PELs vs. RSLs

Chemical PEL ug/m3 RSL ug/m3
Benzene (C) 31,950 1.6
Toluene (NC) 750,000 21,900
Carbon Disulfide (NC) 62,280 307
Benzyl Chloride (C) 5,000 0.25
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PEL Process vs. USEPA Process

• Comparisons of Selected PELs vs. RSLs-recc

Chemical PEL ug/m3 RSL-recc ug/m3 HEAC ug/m3
Benzene (C) 31,950 160 - -
Toluene (NC) 750,000 2,190,000 37,500
Carbon Disulfide (NC) 62,280 30,700 3,130
Benzyl Chloride (C) 5,000 25 172
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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

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Conclusion

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

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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_at_csun.edu