Prediction of Trihalomethanes in water supply of Chattogram city by empirical models and cancer risk through multi-pathway exposure

Abstract

This study predicts the possible occurrence of trihalomethanes (THMs) in water supply of Chattrogram city in Bangladesh, and life time cancer risk from multi-pathway intakes of the trihalomethanes (THMs) to the city dwellers. A total of 11 water samples were collected from the distribution network of the city, and few water quality parameters were analyzed in the study. Three empirical models developed by Amy et al. (1998), Rathbun (1996), and Malcolm Pirnie (1993) were used to estimate the level of THMs from measured water quality data, and were denoted as MODEL1, MODEL2 and MODEL3, respectively in the study. Lifetime cancer risk was estimated using predicted chronic daily intakes (CDI) of THMs' species for different exposure routes (ingestion, inhalation and dermal). The total concentrations of THMs ranged between 20 and 440 μg/L, 95–215 μg/L and 162–249 μg/L were predicted by MODEL1, MODEL2 and MODEL3, respectively. An average lifetime cancer risk was predicted as 1.4 × 10−4, 1.1 × 10−4 and 2.9 × 10−4 for oral, inhalation and dermal exposure, respectively from the water supply of the city. Percent contribution to total lifetime cancer risk were predicted as 50, 40 and10 for oral ingestion, inhalation and dermal absorption, respectively. The study revealed that lifetime cancer risk values were higher than minimum risk level set by United States Environmental Protection Agency. The findings of possible occurrence of THMs in the water supply and associated cancer risk might be beneficial as baseline data for further investigation, and help the decision makers regarding the formulation of standards and legislations of THMs.