Cancer andnon-cancer risk assessment of trihalomethanes in
urban drinking water supplies of Pakistan
abstract
This study aims at monitoring and risk assessment of trihalomethanes (THMs) such as chloroform,bromodichloromethane , dibromochloromethane and bromoform,in the drinking water supplies of Rawalpindiand Is lamabad.THMs were monitored at twenty locations in these twin cities using solid phase microextraction-gaschromatography(SPMEGC).Total concentration of THMs was ranged between 21 and 373 mg/L, where as both cities had an average total THMs concentration of 142 and 260 mg/L, respectively.Chloroform was found as one the major contributor to the THMs concentration (>85%). The occurrence of THMs followed the given order : chloroform, bromodichloromethane > dibromochloromethane >bromoform. Life time cancer risk assessment of THMs was carried out using
prediction models via different exposure routes (ingestion ,inhalation and dermal).An average lifetime
cancer risk was found to be 0.7x103 and 1.24x104 for Rawalpindi and Islamabad, respectively.
The number of expected cancer cases per year could reach two cases for each city. Hazard index values were found below unity for both the cities implying that there would be no considerable non-cancer risk. Oral ingestion was found to be one of the main routes of exposure for both types of risk which was followed by inhalation and dermal routes.