A Comparative Study of Indoor VOC Exposures and Associated Cancer Risk in Four North American Cities

Abstract

WS4-06 Abstract: Recent studies have shown that indoor exposures to volatile organic compounds (VOCs) can significantly contribute to cancer risk. Although indoor VOC levels may originate from outdoor sources, exposures to these compounds are typically controlled by emissions from numerous indoor sources, including building materials, floor and wall coverings, tobacco smoking, consumer products, and volatilization from indoor water use. Although a detailed source apportionment can be difficult in this context, the coincident collection of indoor, outdoor, and personal samples allows for a determination of the relative contribution of source location(s) for measured compounds. Studies that use these methodologies can be used to understand exposure pathways, set research priorities, and design interventions focused on risk reduction. We present the results from personal exposure studies conducted in 4 large North American cities: Boston, New York, Los Angeles, and Mexico City. These studies used personal, indoor, and outdoor air sampling methods to assess the relative contribution of indoor and outdoor sources to personal exposures. These exposure estimates were used to estimate cancer risk through inhalation using published unit risk values. Despite significant ambient sources in large urban areas, indoor VOC sources were shown to contribute a significant portion of cancer risk across these cities. Exposures that contributed significantly to this risk include: 1,4-dichlorobenzene, chloroform, and several aldehydes, particularly formaldehyde. For example, in both Los Angeles and New York, indoor sources of these compounds accounted for more than 40% of the total cancer risk based on personal exposures. These studies highlight the importance of indoor VOC sources as a contributor to health risk. This comparative analysis presents data on the dominant pathways of exposure, the magnitude of cancer risk from measured exposures, and the observed between-city differences that may shed light on controlling variables such as product types, product use patterns, and differences in housing stock.