Asbestos fiber concentration in the area surrounding a former asbestos cement plant and excess mesothelioma deaths in residents.

Kumagai, Shinji; Kurumatani, Norio

BACKGROUND Many persons who had lived near a former asbestos cement plant (AC plant) died from mesothelioma in Amagasaki city, Japan. METHODS Asbestos fiber concentration in the area surrounding the AC plant was estimated so that the female mesothelioma death number predicted by a mathematical model was the same as the observed excess death number. We used the estimated asbestos fiber concentration to predict the excess mesothelioma deaths from 1970 to 2049. RESULTS In a grid just south of the AC plant, the fiber concentration was estimated to be more than 3 f/ml for K(M) (asbestos potency factor for mesothelioma) of 7.75 x 10(-9). An uncertainty factor of five yields a K(M) range 1.55 x 10(-9) to 38.8 x 10(-9); these in turn correspond to fiber concentrations of 15 and 0.6 f/ml. For K(M) = 7.75 x 10(-9), grid units with higher fiber concentrations than 0.01 f/ml were estimated to extend 4.1 km (95% CI: 3.8-4.4 km) south-southwest of the plant. Over the 80-year study period (1970 to 2049), we predicted that the exposure under study will cause 346 excess mesothelioma deaths with range of 296 to 382 deaths. CONCLUSIONS This prediction suggests that considerable medical resources will be needed through 2049 as a result of past asbestos exposure in this region.