Multi-pathway cancer risk assessment of Trihalomethanes exposure from chlorinated tap water and indoor swimming pool

Trihalomethanes (THMs) are the most harmful chlorination by-products that cause cancer in human. The objectives of this research were to investigate concentrations of 4 THMs species: chloroform, bromodichloromethane, dibromochloromethane and bromoform, in tap water and swimming pool water from an indoor swimming pool during May 2007-February 2008 and to assess lifetime cancer risk caused by these substances by the USEPA (1989) method for 6 cases, i.e., adult swimmer, adult non-swimmer, young swimmer, young non-swimmer, swimming teacher and swimming pool staff. Tap water and swimming pool water contained concentrations of total THMs below the standards of WHO, EU and US-EPA while there was no standard of THMs in indoor air. Cancer risks of all 6 cases were in the range of 1.23E-04 - 8.36E-03. All of them exceed the acceptable range recommended by the USEPA. The highest cancer risk was found among the swimming pool staff via inhalation. THMs exposure from indoor swimming pool was the main source of cancer risk. Therefore, organic matters as THMs precursor in water should be reduced and air ventilation system should be improved in order to minimize concentrations of THMs in air.