The assessment of Trihalomethanes (THMs) in household tap water of Perlis

Abstract

Chlorine is commonly used as a disinfectant in drinking water treatment plant in Malaysia for preventing water borne diseases. However, chlorine may react with natural organic matter (NOM) to form trihalomethanes (THMs) and other chlorinated by products that may cause carcinogen to human health. The objective of this study was to measure the concentration level of different THMs species such as chloroform (TCM),bromodichloromethane (BDCM), dibromochloromethane (DBCM) and bromoform (TBM) in household tap water in 4 districts of Perlis, Malaysia with the assess of potential health risk for cancer and non-cancer from exposure to THMs in drinking water through oral ingestion, dermal absorption and inhalation intake by prediction models. TCM was the only THMs compound detected in 80 houses tap water from 4 districts. The samples were prepared undergo liquid-liquid extraction method by using pentane and analyzed by using gas chromatograph mass spectrograph (GCMS). The mean concentration of TCM was 29 μg/L at Kangar, 12 μg/L at Kuala Perlis, 13 μg/L at Arau and 22 μg/L at Jejawi, respectively. The concentrations of samples from 4 districts were under the permissible limit of 300 μg/L for TCM set by World Health Organization (WHO) and the permissible limit of 200 μg/L for TCM set by Malaysia Standard. A mean lifetime cancer risk of TCM was from 8.92×10-7 to 2.17×10-6 by oral ingestion, from 8.63×10-7 to 2.10×10-6 by dermal absorption and from 2.52×10-6 to 6.13×10-6 by inhalation intake, respectively. Hazard index (HI) values were found below unity for 4 districts implying that there would be less non-cancer risk. Inhalation intake was found to be the main routes of exposure for cancer risk. While, oral ingestion was found to be the main routes of exposure for non-cancer risk.