Occupational exposure to trihalomethanes in indoor swimming pools

The study evaluated occupational exposure to trihalomethanes (THMs) in indo or swimming pools. Thirty-two subjects, representing the whole workforce em ployed in the five public indoor swimming pools in the city of Modena (Nort hern Italy) were enrolled. Both environmental and biological monitoring of THMs exposure were performed. Environmental concentrations of THMs in diffe rent areas inside the swimming pools (at the poolside, in the reception are a and in the engine-room) were measured as external exposure index, while i ndividual exposure of swimming pool employees was estimated by THMs concent ration in alveolar air. The levels of THMs observed in swimming pool water ranged from 17.8 to 70.8 mug/l; the mean levels of THMs in ambient air were 25.6 +/- 24.5 mug/m(3) in the engine room, 26.1 +/- 24.3 mug/m(3) in the r eception area and 58.0 +/- 22.1 mug/m(3) at the poolside. Among THMs, only chloroform and bromodichloromethane were always measured in ambient air, wh ile dibromochloromethane was detected in ambient air rarely and bromoform o nly once. Biological monitoring results showed a THMs mean value of 20.9 +/ - 15.6 mug/m(3). Statistically significant differences were observed accord ing to the main job activity: in pool attendants, THMs alveolar air were ap proximately double those observed in employees working in other areas of th e swimming pools (25.1 +/- 16.5 mug/m(3) vs. 14.8 +/- 12.3 mug/m(3), P < 0. 01), THMs in alveolar air samples were significantly correlated with THMs c oncentrations in ambient air (r = 0,57, P < 0.001). Indoor swimming pool em ployees are exposed to THMs at ambient air levels higher than the general p opulation. The different environmental exposure inside the swimming pool ca n induce a different internal dose in exposed workers. The correlation foun d between ambient and alveolar air samples confirms that breath analysis is a good biological index of occupational exposure to these substances at lo w environmental levels, (C) 2001 Elsevier Science B.V. All rights reserved.