Probabilistic Risk-Cost-Benefit Analysis of Additional Benzene Emissions Controls

Size: px

Start display at page:

Download "Probabilistic Risk-Cost-Benefit Analysis of Additional Benzene Emissions Controls"

Merryl Robinson
5 years ago
Views:

1 Probabilistic Risk-Cost-Benefit Analysis of Additional Benzene Emissions Controls Arthur F. Eidson, Ph.D. Senior Risk Assessor The Shaw Group 1401 Enclave Parkway, Suite 250 Houston, Texas June 16, 2010

2 Overview Problem and Objective Emission controls upgrade plant expansion Estimate cost of derived health risk benefit Analytical Methods Analysis of risk, benefit, and cost Uncertainties Probabilistic analysis Conclusions

3 Problem and Objective Petrochemical Plant Expansion Additional equipment required to meet MACT standard for benzene Cost and Benefit Costs being developed by Plant Benefits Continued favorable regulatory compliance Continued good standing with local public groups Increased production throughput What is the cost of the human health risk benefit for benzene vapor controls?

4 Vapor Dispersion Modeling Benzene vapor emission rate estimates Current and proposed control equipment Local meteorological data Dispersion modeling (AERMOD; EPA, 2003) Not strongly sensitive to terrain Predicted/Observed concentrations - City locations Average: 0.70 Range: 0.83 x Average to 1.40 x Average 10th and 90th percentiles of lognormal distribution assumed

5 Receptor Locations

6 Modeled Air Concentrations at City Receptor Locations

7 Inhalation Pathway Exposure C i FLoc i EF i ED i E R = i AT E R = benzene exposure of population R (µg/m 3 ) C i = benzene concentration at location i (µg/m 3 ) FLoc i, EF i (days/year), ED i (years) AT = averaging time (70 years = 25,550 days)

8 Exposure Parameters Receptors Students Hospital Lifetime Residents Workers a Elementary High School College Patient Resident b General Exposure Factors Exposure Frequency, EF (days/year) Exposure Duration, ED (year) - Child c 7 7 Exposure Duration, ED (year) - Adult d Averaging Time-carcinogens, ATc (days) 25,550 Fraction of Time at Location (FLoc) Residence (FRes) 1.00 (1-FW) (1-FEs) (1-FHs) None (1-FH) b Workplace (FW) (8 hr/day) 0.33 FW Elementary School (FEs) (6.5 hr/day) 0.27 FEs High School (FHs) (6.5 hr/day) 0.27 FHs College (FC) (campus resident) 1.00 FC Hospital Patient (FH) (one year) 1.00 FHs a Workers at Schools, College, Hospital b Lifetime resident attending elementary school, high school, college, working at elementary school (highest special location benzene concentration). FRes = (FW+FEs+FHs+FC+FH). c Resident from childhood (age 1 through 7) to adulthood (age 7 through 31). d Resident as adult for entire exposure duration.

9 Risk Characterization General Risk Equation ELCR R E R URF ELCR R = Excess Lifetime Cancer Risk Probability of cancer occurrence from benzene in population R above unexposed population with same characteristics

10 Benzene Toxicity Benzene is a carcinogen URF range (EPA IRIS, 2006) 2.2E-6 (µg/m 3 ) -1 to 7.8E-6 (µg/m 3 ) -1 Age Dependent Adjustment Factor (ADAF) Applies to carcinogens with mutagenic mechanism Benzene action unclear (EPA, 2005), ADAF = 1 here URF assumptions Uniform distribution over URF range

11 Cost Analysis Net Present Value of Proposed Controls Capital Cost of Equipment - $51.7M Assumption: normal distribution ± $100K Operation and Maintenance (O&M) - $100K/yr Assumption: normal distribution ± $10K std dev Depreciation 30 yr Discount Rate 10% (EPA, 1983; OMB, 1996) Assumption: normal distribution ± 1% std dev

12 Health Risk Benefit Analysis Health Benefit Reduced cancer risk achieved by new controls Monetizing benefit is subjective to many risk assessors Economists address willingness to pay (WTP) Such data not available at this time Avoided cancer cases from benzene inhalation discussed here

13 Cost Cost Benefit Ratio Net Present Value of proposed controls ($NPV) Benefit Expected benzene cancer cases = ELCR x City population of 112,000 Avoided cases = Baseline cases Controlled cases Cost/Benefit Ratio Cost/Benefit = $NPV per Benzene Cancer Cases Avoided

14 Probabilistic Analysis Effect of Uncertainty Assumptions on: Risk Estimates (Cancer Cases Avoided) Benzene concentrations, occupancy factors, toxicity factors Cost Estimates ($NPV) Capital, O&M, depreciation, discount rate Cost/Benefit Ratio $NPV / Benzene Cancer Case Avoided

15 Modeled Baseline Concentrations

16 Modeled Controlled Concentrations

17 Maximum Reduction in Risk

18 Risk Benefit

19 Cost Estimate

20 Cost per Cancer Case Avoided

21 Cost per Cancer Case Avoided

22 Cost / Benefit Ratio Mean Value Estimate Average = $72.4M per case Most likely = ~$67M per case 95% probability $43M to $117M per case

23 Conclusions Most likely cost per benzene cancer case avoided somewhat similar to capital cost (~$52M) Other benefits not considered here Cancer reduction from carcinogens other than benzene Regulatory compliance (penalties avoided) Continued good public standing Increased production from upgraded plant

24 References U.S. Environmental Protection Agency (USEPA), 2003, AERMOD: Latest Features and Evaluation Results, EPA-454/R , June. U.S. Environmental Protection Agency (USEPA), 2008, Integrated Risk Information System (IRIS), accessed at U.S. Environmental Protection Agency (USEPA), 2005, Guidelines for Carcinogen Risk Assessment, EPA/630/P-03/001B, Risk Assessment Forum, Washington, D. C. March 25. U.S. Environmental Protection Agency (USEPA), 1983, Guidelines for Performing Regulatory Impact Analysis, as updated through 1991, Office of Policy, Planning, and Evaluation, Washington, D. C. Office of Management and Budget (OMB), 1996, Economic Analysis of Federal Regulations Under Executive Order 12866, January 11.

Disclaimer To the extent permissible by law, The Shaw Group assumes no responsibility for information presented herein and disclaims all liability in respect of such information.

25 Disclaimer To the extent permissible by law, The Shaw Group assumes no responsibility for information presented herein and disclaims all liability in respect of such information. Shaw is not liable for any injury and/or damage to persons or property as a result of any actual or alleged infringements of intellectual property or privacy rights, professional or product liability, whether resulting from negligence or otherwise, including without limitation, from any use or operation of any ideas, instructions, procedures, products or methods contained in the material presented herein. Shaw does not warrant that the information provided is accurate or free from error. Information provided is intended solely for the purpose of providing general information.

1, 2, 3-Trichloropropane (TCP): Assessment of Risks from Drinking Water

1, 2, 3-Trichloropropane (TCP): Assessment of Risks from Drinking Water 1, 2, 3-Trichloropropane (TCP): Assessment of Risks from Drinking Water Prepared for Alaimo Group (Engineers and Architects) 200