Disinfection of swimming pools with chlorine and derivatives: formation of organochlorinated and organobrominated compounds and exposure of pool personnel and swimmers

Chlorination of pool water leads to the formation of many by-products, chloroform usually being the most abundant. The paper reports the results of a study evaluating exposure of bathers and pool employees to trihalomethanes (chloroform, bromodichloromethane, dibromochloromethane, bromoform) in four indoor swimming pools with chlorinated water. Chloroform concentrations in environmental air samples when the pool was in use (about 9 h), in the range 1-182 μg/m, were greater near the pool than in the change rooms, passageways and offices. Chloroform concentrations in personal air samples of pool employees were in the range 18-138 μg/m. Urinary concentrations of chloroform averaged (geometric means) 0.123 and 0.165 μg/l and 0.404 and 0.342 μg/l prior and at the end of exposure during in water and out of water activities, respectively. The significant increase in urinary excretion of chloroform confirms that the source of the contaminant was pool water. Absorption of chloroform, estimated from airborne and water concentrations, was significantly correlated with delta chloroform (after/before exposure) and urinary concentrations of chloroform at the end of exposure. As chloroform is a toxic and possibly carcinogenic substance, these observations pose a problem principally for the general population of pool users.