Swimmers exposed to disinfection by-products in indoor swimming pools exhibit genotoxicity. - GreenMedInfo Summary

BACKGROUND: Exposure to disinfection by-products (DBPs) in drinking water has been associated with cancer risk. A recent study found an increased bladder cancer risk among subjects attending swimming pools relative to those not attending. OBJECTIVES: To evaluate whether swimming in pools is associated with biomarkers of genotoxicity. METHODS: We collected blood, urine, and exhaled air samples from 49 non-smoking adult volunteers before and after they swam for 40 min in an indoor chlorinated pool. We estimated associations between the concentrations of four trihalomethanes in exhaled breath and changes in the following biomarkers: micronuclei and DNA damage (comet assay) in peripheral blood lymphocytes before and 1 h after swimming, urine mutagenicity (Ames assay) before and 2 h after swimming, and micronuclei in exfoliated urothelial cells before and 2 weeks after swimming. We also estimated associations and interactions with polymorphisms in genes related to DNA repair or DBP metabolism. RESULTS: After swimming, the total concentration of the four trihalomethanes in exhaled breath was seven times higher than before swimming. The change in the frequency of micronucleated lymphocytes after swimming increased in association with exhaled concentrations of the brominated trihalomethanes (p = 0.03 for CHCl2Br, p = 0.05 for CHClBr2, p = 0.01 for CHBr3) but not chloroform. Swimming was not associated with DNA damage detectable by the comet assay. Urine mutagenicity increased significantly after swimming in association with the concentration of exhaled CHBr3 (p = 0.004). No significant associations with changes in micronucleated urothelial cells were observed. CONCLUSIONS: Our findings support potential genotoxic effects of exposure to DBPs from swimming pools. The positive health effects gained by swimming could be increased by reducing the potential health risks of pool water.