1. ChemRisk Houston Air Quality: Modeling, Monitoring and Risk Associated with Hazardous Air Pollutants (HAPs) Mark Harris, PhD Principal Health Scientist ChemRisk Inc. Houston Air Toxics Workshop II June 12, 2007

2. ChemRisk Houston Air Quality: Outline Recent Events Mayor’s Task Force Report –data utilized –risk characterization Conclusions

3. ChemRisk Current Situation Houston complies with Clean Air Act (CAA) criteria pollutant standards except for ozone Coming into compliance with the CAA ozone standard is important: –Human health (asthma) –Federal funding –Remain competitive with other metropolitan areas

4. ChemRisk Current Situation Table from “The State of Health” Report for Houston and Harris County (2007)

5. ChemRisk Houston Air Quality: HAPs Recent Events 2005 – “In Harm’s Way” series by Dina Cappiello Four neighborhoods near industrial facilities Compared results to ESLs and to more stringent values used by the federal government and other states Compared results to NATA background Assessed TCEQ monitoring data/some in home sampling as well Summer 2006: Mayor’s Task Force report Survey of 179 air pollutants, 10 county area Used modeled annual average air concentrations from EPA’s 1999 National Air Toxics Assessment (NATA) and some monitoring data Ranked pollutants based on theoretical cancer risk

6. ChemRisk September 2006: The Control of Air Toxics Report Rice University, UH Law Center, Baylor College of Medicine, Texas Southern University, and UTMB 4 HAPs: benzene, 1,3-butadiene, formaldehyde, diesel particulates Follow up to Mayor’s Task Force Report Based on TCEQ monitoring data and compared concentrations to other cities Houston Air Quality: HAPs Recent Events

7. ChemRisk 2007: UT School of Public Health Preliminary Report Retrieved Texas Cancer Registry Data TCEQ & NATA data for benzene and 1,3-butadiene Estimated rate ratios based on distance from HSC and air concentrations 2007: Mayor’s benzene reduction plan Focused on ship channel facilities Suggested modifications for facilities Houston City Council authorized litigation Novel in that most facilities targeted are not in Houston Houston Air Quality: HAPs Recent Events

8. ChemRisk Reports have limitations –Selection of modeling data –Modeled values reflect upper bound of monitoring data –Use of worst-case toxicity values –Risks not placed into perspective –Transparency –Statistical procedures unclear –Lack of cost benefit analyses –Errors in reported information –Failure to consider met data in some cases –Reports comprise parts of a risk assessment but we are missing key pieces Houston Air Quality: HAPs Recent Events

9. ChemRisk Risk Assessment - HAPs RiskCharacterization Dose-ResponseAssessment RiskManagement HazardIdentification ExposureAssessment Cost/BenefitAnalyses 1 2 3 4

10. ChemRisk Focus on Mayor’s Task Force Report

11. ChemRisk Mayor’s Task Force Report Utilized ASPEN data as opposed HAPEM Some use of monitoring data Higher of CAL EPA or EPA toxicity criteria for a chemical Calculated cancer risk on a census tract basis using ASPEN data Ranked chemicals using risk estimates Forms basis for other reports and recent actions by Mayor’s office

12. ChemRisk Houston Air Quality: Mayor’s Report 12 chemicals flagged as “definite” risks: “Those substances for which there was compelling and convincing evidence of significant risk to the general population or vulnerable subgroups at current ambient concentrations..”

13. ChemRisk Definite Health Risks per the Mayor’s Task Force Report Ozone Fine Particulate Matter 1,3-Butadiene Chromium VI Benzene Ethylene dibromide Acrylonitrile Formaldehyde Acrolein Chlorine Hexamethylene Diisocyanate Diesel Particulate Matter

14. ChemRisk Our Evaluation Comparison of NATA modeled air concentrations for certain HAPs to monitoring results Risk Characterization –Sprinkles, a thunderstorm or hurricane?

15. ChemRisk NATA Air Modeling As part of NATA, air concentrations were modeled by EPA using ASPEN and HAPEM for 895 census tracts in our 10 county area Air concentrations used by EPA to predict risk 1999 vintage information We pulled the modeled air concentrations into ArcGIS, and plotted with TCEQ air monitoring locations

16. ChemRisk Houston Air Quality: Air Modeling Benzene1,3 Butadiene

17. ChemRisk Houston Air Quality: Monitoring Data Obtained air monitoring data from TCEQ for several HAPs 24 hour canisters taken every 6 th day 15 sites available, east Harris County 13 sites 2003-2006, 2 sites 2005-2006 Hourly auto GC data 8 sites available, east Harris County 6 sites 2003-2006, 1 site 2005-2006, 1 site 2004-2006

18. ChemRisk Houston Air Quality: 24 hour canister data Period of Record: 1/2003 to 1/2006 160 measurements, 24 hour canisters collected every 6 days

19. ChemRisk Houston Air Quality: Auto GC data Period of Record: 1/2003 to 8/2006 N Benzene = 1131 N 1,3 Butadiene = 902 Auto GC data used to determine daily averages

20. ChemRisk Results for Channelview monitor typical Results for Auto GC daily averages matches well with 24 hour cans taken every 6 days Modeled benzene concentration typically at or greater than the 90 th percentile of monitoring data Modeled 1,3-butadiene concentration typically at or greater than 70 th percentile, often over 80 th percentile Houston Air Quality: Modeled vs. Monitored Air Concentration

21. ChemRisk Mayor’s Task Force Report Our attempt to place the risks into perspective

22. ChemRisk Risk Characterization Total excess cancers for census tract over a lifetime = CR x pop –where, CR = cancer risk in a census tract for an airborne pollutant pop = population of census tract Example –population of a census tract = 4,000 people –theoretical excess cancer risk for a chemical = 1 x 10 -5 –Total excess cancers for census tract = 4,000 x 1 x 10 -5 –Total excess cancers for census tract = 0.04

23. ChemRisk Total Excess Cancers for the 895 Census Tracts in the 10 County Area Chemical USEPA Toxicity Criteria Number of Excess Cancers CalEPA Toxicity Criteria Number of Excess Cancers Acrylonitrile520 Cr VI23282 EDB268 Formaldehyde060 Benzene68253 Butadiene23131 Total144754

24. ChemRisk Risk Characterization In the population of the study area (4,715,407), approximately 1 in 3 (or 1,556,085) will develop cancer in their lifetime 33% background rate Using EPA Toxicity Criteria - these HAPs add an additional 0.003% to the background rate over a lifetime Using CAL EPA Toxicity Criteria - these HAPS add an additional 0.016% to the background rate over a lifetime Excess cancers associated with these chemicals would be very difficult if not impossible to detect Risk characterization does not support the conclusion that there is “compelling and convincing evidence of significant risk” associated with these HAPs

25. ChemRisk Risk Characterization Table from “The State of Health” Report for Houston and Harris County (2007)

26. ChemRisk Risk Characterization Table from “The State of Health” Report for Houston and Harris County (2007)

27. ChemRisk Conclusions Mayor’s Report missing perspective Modeling data is conservative relative to measured air concentrations in the Houston area Risk Characterization indicates a level of increased risk that would be very difficult to detect More important to focus meeting ozone criteria

28. ChemRisk Co-Authors Dr. Laurie Haws Mr. Andrew Tachovsky Dr. Spencer Williams Ms. Ly Nguyen Ms. Laura Scott

29. ChemRisk Thank you! Are there any questions? For further information: Mark Harris, Ph.D. Principal Health Scientist ChemRisk, Inc. 10375 Richmond Ave, Suite 350 Houston, TX 77042 phone: 713-974-6200 ext. 1001 fax: 713-974-6111 email: mharris@chemrisk.com