Trihalomethanes and associated potential cancer risks in the water supply in Ankara, Turkey

The occurrence of trihalomethanes (THMs) in the water supply in the Ankara, Turkey was investigated. Total THMs and total organic carbon measurements were carried seasonally in the samples collected form 22 different districts along with the samples taken from the Ivedik Water Treatment Plant serving 90% of the city. The average summer nonpurgeable organic carbon (NPOC) concentration in the raw water was 4.2 mg/L, and the NPOC removal achieved in the treatment plant was 31%. The concentration of total THMs ranged from 25 to 74 μg/L, from 28 to 73 μg/L, and from 25 to 110 μg/L in winter, spring, and summer, respectively. In all of the samples chloroform existed at the highest concentrations, while bromoform was almost absent. The total THM concentrations were highest in summer for all districts. However, none of the concentrations detected exceeded the USEPAʹs Stage I limit of 80 μg/L and the EUʹs limit of 100 μg/L. However, the total THM level in 64% of the districts exceeded the USEPAʹs Stage II limit of 40 μg/L. The risk estimations carried out indicated that each year 1 of the 5 million Ankara residents could get cancer from the daily intake of water, mainly because of exposure to chloroform through oral ingestion.