抄録
Naphthalene is the most abundant polycyclic aromatic hydrocarbon for environmental exposure of humans and its carcinogenicity in rodents was recently demonstrated. Naphthalene concentrations in indoor and outdoor air of 30 residences of general public living in Metropolitan Tokyo and Hyogo Prefecture were measured. Median concentrations of naphthalene in indoor air was 0.37 (range: 0.15 to 58) and 0.43 (0.16-19) μg/m3 for living room (n=30) and bed room (n=18), respectively, with a great residence-to-residence variability. They were higher than the concentration in outdoor air (median: 0.16 μg/m3). Indoor to outdoor ratio (I/O) of naphthalene concentration ranged from 0.4 to 275: it was >1.0 for 26 out of 30 residences. This indicated that indoor source(s) of naphthalene is present in most of the residences. Since lifetime cancer risk posed by inhalation of naphthalene in indoor and outdoor airs at the present level was calculated to be >105, risk reduction was desirable. Elevated concentration of indoor naphthalene was found after cooking in five residences indicating that cooking can be one of the common sources of naphthalene across residences. Investigation of two residences with greater I/O revealed that repellent can be a significant source of indoor naphthalene.
