USA miscalculates cancer risk
the us Environmental Protection Agency (epa) vastly underestimates the cancer risk from exposure to volatile organic compounds (vocs), which are used for manufacturing many household and industrial products. Researchers from the us-based Johns Hopkins Bloomberg School of Public Health found that residents of Baltimore face three-fold greater cancer risk than what epa claims.
The researchers are the first to compare actual voc exposure levels with the results of epa's Assessment System for Population Exposure Nationwide (aspen) model, which mainly relies on ambient voc levels. During their study, 'Personal exposure meets risk assessment: a comparison of measured and modelled exposures and risks in an urban community', the researchers calculated ambient as well as indoor and personal voc exposure levels of 33 non-smoking adults.
For vocs having significant indoor sources, such as chloroform, the researchers found that aspen far underestimated the exposure levels. In contrast, aspen estimates for vocs from vehicles were in tandem with the new measurements. When the researchers combined the exposure level of all vocs, they found that aspen miscalculated the risk by a factor of three. Benzene, carbon tetrachloride and chloroform accounted for maximum risk.
The results, published in the April 2004 issue of the journal Environmental Health Perspectives, indicate that us citizens are routinely exposed to a number of vocs considered to be toxic air pollutants by the epa. Moreover, the exposure levels are far above the public health benchmarks. "Our results show that indoor exposure to vocs accounts for a sizeable fraction of the risk. Therefore, epa needs to disseminate information about how to avoid indoor exposure," says Devon C Payne-Sturges, the lead author of the study.
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