Comparison of risks from outdoor and indoor exposure to toxic chemicals

Environmental Protection Agency TEAM (Total Exposure Assessment Measurement) Studies have measured exposures of about 800 persons to 25 volatile organic compounds (VOCs) and exposures of about 300 persons to 32 pesticides. These persons were selected to represent more than 1 million residents of industrial manufacturing cities such as Bayonne and Elizabeth, New Jersey, and Los Angeles, California; cities with light industry, such as Greensboro, North Carolina, and Baltimore, Maryland; rural areas such as Devils Lake, North Dakota; and cities with high pesticide use such as Jacksonville, Florida, as well as low-to-moderate pesticide use such as Springfield, Massachusetts. The TEAM data provide an opportunity to estimate the risks from airborne exposure to a number of suspected carcinogens for a substantial number of persons residing in a wide variety of urban, suburban, and rural areas. Because all of the TEAM Studies measured outdoor concentrations near the homes of the participants, it is possible to apportion the risks between outdoor and indoor sources. Upper-bound lifetime risks of cancer are calculated for both indoor and outdoor sources of 12 VOCs and about 23 pesticides measured in the TEAM Studies. These risk calculations are supplemented by calculations based on other studies for some additional pollutants, including radon and environmental tobacco smoke. The relationship of these upper-bound risk estimates to "best-guess" values is discussed. Sharper estimates of risk based on identifying population subgroups exposed to major sources are also discussed. Important gaps in our knowledge of exposure measurements are identified, e.g., particulates (including polyaromatic hydrocarbons); 1,3-butadiene, asbestos, chromium, cadmium, arsenic, vinyl chloride, methylene chloride, and most polar organics.