Reduction of DBPs in synthetic water by indoor techniques and its implications on exposure and health risk.

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Disinfection byproducts (DBPs) in municipal supply water have been a concern. Many DBPs have been characterized as possible and probable human carcinogens, which can pose elevated cancer risks through lifetime exposure to municipal supply water. Few DBPs are regulated in many countries to control human exposure and risk from DBPs. In risk assessment studies, concentration of DBPs in water distribution systems is often used, whereas populations are typically exposed to indoor tap water. Through employing several techniques, DBPs can be reduced prior to water consumption, which is likely to reduce human exposure and risk of DBPs. This study investigated six indoor techniques in reducing trihalomethanes (THMs) and haloacetic acids (HAAs) in synthetic water and the effects of these techniques on exposure and risk. The techniques are: S1, S2: storing water in a refrigerator with and without lids respectively; S3, S4: boiling water for 1 min followed by storing in a refrigerator with and without lids respectively; S5, S6: filtering water using new and used granular activated carbon (GAC) filters and storing in a refrigerator without lids. Storing of water (S1, S2) reduced THMs in the range of 14.8-47.2% while boiling (S3, S4) and filtration (S5, S6) reduced THMs in the range of 77.3-92.8%. In S1-S4 techniques, HAAs were not reduced significantly while in S5 - S6 techniques, HAAs were reduced in the range of 64.7-69.8%. In S3-S6 techniques, overall cancer and non-cancer risks were reduced by 45.5-82.6% and 26.3-80.0% respectively. The findings might prove useful in understanding DBPs exposure, associated risks, strategies to minimize exposure to these contaminants and updating regulatory guidelines for better protection of health risks from DBPs.