OBJECTSWe carried out an investigation to clarify the real state of indoor air pollution by chlorpyrifos (termiticide) and exposure to chlorpyrifos of residents by measuring its urinary metabolite 3,5,6-trichloro-2-pyridinol (TCP) as an exposure index, such as biological monitoring.

METHODSThe investigation was conducted in 43 individual houses with termiticide application (whether the termiticide was chlorpyrifos is uncertain) and 3 control houses without any termiticide application in Kagawa, Japan. Urine samples were collected from 46 healthy adult residents of the aforementioned houses.

RESULTSChlorpyrifos in indoor air in the control houses was not detected (ND<1 ng/m(3), n=3), while 41 of 43 houses with termiticide application showed 1-350 ng/m(3). Although the chlorpyrifos concentrations in these 41 houses did not exceeded the indoor air quality guideline of 1000 ng/m(3), but 3 houses were higher than the guideline 100 ng/m(3) for children in Japan. Urinary TCP concentrations of 0.1-7.8 ng/mg·creatinine were detected in 41 residents from the 41 houses where chlorpyrifos had been detected. The chlorpyrifos concentration and the urinary TCP revealed a positive correlation (r=0.5468, p<0.01, n=41).

CONCLUSIONSThe immediate health hazard from air born chlorpyrifos in the examined houses was negligible, but the findings suggest that it is necessary to monitor chemicals which may contaminate indoor air and to assess the risk of prolonged exposure to such chemicals. The measuring of urinary metabolite TCP of chlorpyrifos via biological monitoring would be useful, allowing comprehensive evaluation of the exposure to chlorpyrifos in indoor air.