Trihalomethane levels in Madras public drinking water supply system and its impact on public health.
It is known that trihalomethanes (THM) are formed during chlorination of drinking water for disinfection. Heightened concern about these substances is due to the fact that THMs are now characterized as potential mutagen, carcinogen and teratogen. Thus, it is a risk factor in human beings. In the present study, a total number of 13 stations located in different drinking water trunk mains of the city of Madras were analysed for THM using the Gas Liquid Chromatographic method. It is reported that THM are formed after treatment of raw water with chlorine at the levels required for disinfection. The THM level in drinking water increased towards the dead-end of the water trunk mains. A relationship between the distance travelled by the potable water and the level of THM was established. At certain stations, the total trihalomethanes level (TTHM) was found to exceed the EPA's maximum contaminant level. Further, an intermittent addition of the precursors for the formation of THM through the seepage of polluted River Cooum water into the pipe lines has been demonstrated. An experiment on the trihalomethane formation potential (THMFP) clearly revealed the occurrence of higher magnitude of humic substances in source water. Therefore, it is suggested that if suitable steps are not taken, various environmental factors may trigger the THM kinetics. Hence, it is obvious that pretreatment regulations proposed by developed countries are essential if safe drinking water is to be supplied to the people of Madras.
Rajan
S
S
Department of Zoology, University of Madras, India.
Azariah
J
J
Bauer
U
U
D002725:Chloroform / Q000032:analysis; D006801:Humans; D006842:Hydrocarbons, Brominated / Q000032:analysis; D006846:Hydrocarbons, Halogenated / Q000032:analysis*; D007194:India; D022882:Trihalomethanes; D014877:Water Pollution, Chemical / Q000032:analysis*; D014881:Water Supply / Q000032:analysis* / Q000592:standards
D006842:Hydrocarbons, Brominated; D006846:Hydrocarbons, Halogenated; D022882:Trihalomethanes; C032707:chlorodibromomethane; C025191:bromodichloromethane; D002725:Chloroform; C015044:bromoform