水銀作業場におけるスペ-ス・モニタリング法の個人暴露量の比較

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This study was undertaken to determine whether or not biological levels of mercury correlate better to values of exposure to mercury estimated by personal monitoring methods than to those obtained by conventional environmental monitoring methods. Mercury was collected for personal monitoring by amalgamating mercury vapor with gold wire in a glass tube attached to a worker's collar, and for environmental monitoring by placing bubblers containing a scrubbing solution of acidic permanganate in the work area. Individual levels of exposure to mercury were based on an 8-hour time weighted average (TWA).Six workers from a thermometer manufacturing plant and from the same workshop were divided into two job groups for study. One, the indirect contact group consisted of 3 packers who did not handle metallic mercury and two, the direct contact group, of 3 machine operators who came into direct contact with the chemical.1. For the indirect contact group, the TWA exposure levels for environmental monitoring and personal monitoring were equal. For the direct contact group, TWA exposure levels obtained by personal monitoring were 70% higher than those by environmental monitoring.2. The TWA exposure (μg/cu m)/Urine (μg/dl) ratio in the direct contact group, when estimated by environmental monitoring, approximated 2.9 (2.2-3.5) and when estimated by personal monitoring, approximated 4.8 (4.2-5.9). The ratio obtained by personal monitoring was about 1.7 times higher than that by environmental monitoring. In contrast, the TWA exposure/Urine ratio in the indirect contact group approximated 5.1 (4.4-5.9) when monitored by environmental methods and 5.7 (5.3-6.2) by personal methods. The ratios obtained by the two different methods were in close agreement in this case.3. The TWA exposure (μg/cu m)/Blood (μg/l) ratio in the direct contact group, when estimated by environmental monitoring, approximated 0.7 (0.6-0.9) and when estimated by personal monitoring, approximated 1.2 (1.0-1.4). However the TWA/Blood ratios estimated by environmental monitoring and by personal monitoring were 1.3 (1.2-1.4) and 1.4 (1.3-1.5) respectively for the indirect contact group.From the above results, it is clear that the levels of individual exposure indicated by environmental monitoring, were lower than what was, in fact, the actual exposure. Therefore, it is recommended that personal monitoring be used to estimate worker exposure to mercury vapor when there is potential contact with metallic mercury and when air mercury levels fluctuate.4. Since mercury vapor emanating from contaminated clothing may be a significant source of additional exposure for workers, such concentrations of mercury vapor from workers' clothing were also measured. Vapor which emanated from clothing over an 8-hour period were at levels of 19-218μg Hg for the indirect contact group and 200-897μg Hg for the direct contact group. If one assumes that floor space per individual is 10m3, and that workers usually wear the same contaminated clothing for an entire 8-hour day, the extrapolated mercury levels for workers exposed to mercury from clothing would be 20-90μg Hg/cu m. In the National Institute for Occupational Safety and Health criteria for mercury, "exposure" is defined as exposure to levels above 20μg Hg/cu m of air. Therefore, it is evident that the levels of mercury emanating from clothing can not be ignored when sources of exposure to mercury are being considered.
日本衛生学会の論文

水銀作業場におけるスペ-ス・モニタリング法の個人暴露量の比較

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日本衛生学会 | 論文

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