| Ranking Cancer Risks of Organic Hazardous Air Pollutants in the United States Miranda M. Loh,1, 2 Jonathan I. Levy,2 John D. Spengler,2 E. Andres Houseman,2,3 and Deborah H. Bennett2,4 1KTL, National Public Health Institute, Department of Environmental Health, Kuopio, Finland; 2Harvard School of Public Health, Department of Environmental Health, Cambridge, Massachusetts, USA; 3University of Massachusetts, Lowell, Department of Work Environment, Lowell, Massachusetts, USA; 4University of California, Davis, Department of Public Health Sciences, Davis, California, USA Abstract
Background: In this study we compared cancer risks from organic hazardous air pollutants (HAPs) based on total personal exposure summed across different microenvironments and exposure pathways. Methods: We developed distributions of personal exposure concentrations using field monitoring and modeling data for inhalation and, where relevant, ingestion pathways. We calculated risks for a nonoccupationally exposed and nonsmoking population using U.S. Environmental Protection Agency (EPA) and California Office of Environmental Health and Hazard Assessment (OEHHA) unit risks. We determined the contribution to risk from indoor versus outdoor sources using indoor/outdoor ratios for gaseous compounds and the infiltration factor for particle-bound compounds. Results: With OEHHA's unit risks, the highest ranking compounds based on the population median are 1,3-butadiene, formaldehyde, benzene, and dioxin, with risks on the order of 10–4–10–5. The highest risk compounds with the U.S. EPA unit risks were dioxin, benzene, formaldehyde, and chloroform, with risks on a similar order of magnitude. Although indoor exposures are responsible for nearly 70% of risk using OEHHA's unit risks, when infiltration is accounted for, inhalation of outdoor sources contributed 50% to total risk, on average. Additionally, 15% of risk resulted from exposures through food, mainly due to dioxin. Conclusions: Most of the polycyclic aromatic hydrocarbon, benzene, acetaldehyde, and 1,3-butadiene risk came from outdoor sources, whereas indoor sources were primarily responsible for chloroform, formaldehyde, and naphthalene risks. The infiltration of outdoor pollution into buildings, emissions from indoor sources, and uptake through food are all important to consider in reducing overall personal risk to HAPs. Key words: hazardous air pollutants, personal exposure, polycyclic aromatic hydrocarbons, risk assessment, volatile organic compounds. Environ Health Perspect 115:1160–1168 (2007) . doi:10.1289/ehp.9884 available via http://dx.doi.org/ [Online 15 May 2007]
Address correspondence to M.M. Loh, KTL, National Public Health Institute, Department of Environmental Health, P.O. Box 95, 70701 Kuopio, Finland. Telephone: +358 17 201 394. Fax: +358 17 201 184. E-mail: miranda.loh@ktl.fi This study was supported by the International Society for Exposure Analysis (ISEA) Young Investigator Award to D.H.B. The authors declare they have no competing financial interests. Received 6 November 2006 ; accepted 15 May 2007.
Correction Equation 1 was incorrect in the original manuscript published online ; it has been corrected here.
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