気相曝露量の実態調査に基づいた水道水中トリハロメタンの曝露量と飲用寄与率の評価

摘要

The concentrations of trihalomethanes (THMs) in air and tap water were surveyed in 30 households (including a few duplicate ones) to estimate the exposure amount of THMs in Japan. Airborne THMs of bathrooms, bedrooms, kitchens, and outdoors around houses were adsorbed on Tenax-TA, and then analyzed using GC-MS. The medians concentration of airborne total trihalomethanes (TTHMs) were 56.5 μg/m~3 (bathroom), 1.62 μg/m~3 (kitchen), 0.94μg/m~3 (living room), and 0.29 μg/m~3 (outdoor). It was found that TTHMs in bathrooms was higher than in living rooms and kitchens. The exposure amounts of THMs from dietary were estimated based on literature data. Considering the exposure amounts from water and air estimated. The average allocations to trihalomethanes exposure via drinking water were 16% (TCM), 24% (BDCM), 20% (DBCM) and 7% (TBM). The average total exposures to trihalomethanes from water, air and dietary were 37.8μg/day (TCM), 23.3μg/day (BDCM), 19.9μg/day (DBCM) and 10.9μg/day (TBM), and the ratios of the average exposures to TDI adopted by WHO in GDWQ were 6% (TCM), 8% (BDCM), 2% (DBCM) and 1% (TBM), respectively.%わが国の一般住居における水道水に起因するトリハロメタンのヒトへの曝露の実態を明らかにrnするため、気相曝露に着目し実態調査を行った。浴室、台所、居間および屋外の空気ならびに給水栓水rnについて、近畿地方の延べ30軒で測定した。空気中の総トリハロメタン（TTHM）の濃度（中央値）は、rn浴室56.5μg/m~3、台所1.62μg/m~3、居間0.94μg/m~3、屋外0.29μg/m~3であり、浴室の濃度は、台所やrn居間と比べて大きな値を示した。水相、気相、食品による曝露量を推計し、平均的な飲用寄与率を算定rnすると、TCM16％、BDCM24％、DBCM20％、TBM7％となった。また、平均的な曝露量の合計は、rnTCM37.8μg/day、BDCM23.3μg/day、DBCM19.9μg/day、TBM10.9μg/dayとなり、経口曝露のTDIrn相当値と比較すると、TCM6％、BDCM8％、DBCM2％、TBM1％であり十分に低い値であった。