降雪地域における1-nitropyreneと浮遊粉塵による冬季の大気汚染

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Nitroarenes, potent rodent carcinogens, have attracted much attention as environmental contaminants. Recently, simultaneous exposure to dust have been found to potentiate tumorigenicity of nitroarenes in rats (14). We hypothesized that inhabitants of northwestern Japan may be exposed to such substances in winter. First, we sought to develop a sensitive yet time saving method to determine nitroarene concentrations in airborne particulate matter. The method developed used a highperformance liquid chromatograph equipped with a fluorescence detector. By on-column catalytic reduction, using silica coated with platinum and rhodium, 1-nitropyrene (1-NP), 1, 3-dinitropyrene, 1, 6-dinitropyrene, and 1, 8-dinitropyrene were effectively reduced to their amino derivatives which were easily detectable with the fluorescence detector. The lowest detectable limits found using the present method were on the order of picograms for individual compounds. Subsequently, we sought to determine the concentrations of nitroarenes using the new method on airborne particulate matter during the period from November to April. Samples were collected at sampling sites on road with high-volume air samplers for 24 hours or 72 hours in four different rural areas in Iwate Prefecture. At one location in the city of Morioka, samples were collected at the height of 25m from the ground. Among the four nitropyrenes mentioned above, only 1-NP was detected in the samples. The concentrations of 1-NP and airborne particulates changed significantly in all examined areas in parallel with the rise and fall of the frequencies of studded tire use. The highest 1-NP and airborne particulate concentrations were 1, 210pg/m3 and 1, 291μg/m3, respertively, being recorded at the busiest road in Kitakami. In contrast, the lowest values were 38 to 66pg/m3 for 1-NP and 54 to 94μg/m3 for airborne particulates in Morioka, being recorded in November and Aprill, respectively. The mutagenicities of extracts of airborne particulate matter showed similar trends. Thus, exposure situations with high concentrations of dust and 1-NP were confirmed to occur in Iwate. Finally, the risk posed by 1-NP in airborne particulate matter was estimated using the equation proposed by Cuddihy and McClellan (37) and was found to range from 3.12×10-2 to 24.2×10-2 lung cancer/year/106 people. Although the estimated risk due to 1-NP is relatively small, further surveillance is highly recommended in those areas since heavy dust exposure also occurs there.
日本衛生学会の論文

降雪地域における1-nitropyreneと浮遊粉塵による冬季の大気汚染

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