Malignant mesothelioma is a well-recognized risk of exposure to asbestos, and the disease may occur after relatively brief, low-level, or indirect exposures. Consequently, there have been concerns regarding exposures to asbestos contaminating the environment.1One highly publicized example is contamination of the town of Libby, MT, by tremolite asbestos occurring in the nearby vermiculite mine.2 Recently, the Agency for Toxic Substances and Disease Registry convened an expert panel in Atlanta, GA, to discuss the potential risks of environmental asbestos contamination in communities throughout the United States. A number of questions remain unanswered. What is the magnitude of the risk (if any) to these communities? Can the risks be quantified, and what are the parameters that best predict the risk of mesothelioma? Are there gender differences in susceptibility, and are young children who are exposed to asbestos (eg, on playgrounds) at greater risk than adults?