Title: Can USEPA-RAGS Risk Assessment Methodology be Applied to the Workplace?
1Can USEPA-RAGS Risk Assessment Methodology be
Applied to the Workplace?
- Michael J. Sullivan, Ph.D., CIH, REA
- California State University at Northridge
2(No Transcript)
3- This sentence assembled itself.
4What Can We Use?
OELs
PELs
Protecting The Worker
Precautionary Principle
USEPA RAGS HRA
5Outline
- PEL-Setting Process
- USEPA Risk Assessment Process
- Comparison of Processes
- Comparison of Results
- Recommendation
6PEL-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
7PEL-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
8USEPA Risk Assessment Process
9USEPA 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
10USEPA Risk Assessment Process
- Calculations slightly different for carcinogens
vs. non-carcinogens - Based on assumption of non-threshold vs.
threshold mechanisms of action
11USEPA Risk Assessment Process
- Carcinogenic risks is Incremental Lifetime Cancer
Risk (ICLR) - Non-carcinogenic risk is Hazard Quotient (HQ)
12USEPA 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)
13USEPA 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)
14USEPA 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)
15USEPA 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)
16USEPA 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/
17USEPA 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
18USEPA Risk Assessment Process
- USEPA RSLs (306)
- 127 for carcinogenic chemicals
- 134 for non-carcinogenic chemicals
- 45 for both C and NC chemicals
19PEL Process vs. USEPA Process
- PELs
- Require consensus
- Enforcable
- Weighted towards workplace epidemiology
- RSLs
- Easy to calculate
- Not enforceable
- Weighted towards toxicology data
20PEL 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
21PEL 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
22PEL 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
23PEL 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
24PEL 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
25PEL 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
26PEL 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
27Recommendation
- 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
28Conclusion
- The combined use of the PELs and RSLs can
effectively protect worker health
29Contact 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