Toxicological evaluation of drinking water in Beijing waterworks

The mutagenicity and acute toxicity of source water, water from five different treatment units as well as tap water from waterworks in Beijing were studied. The aim of this research was to examine the seasonal variation of water toxicity during water treatment processes, and to evaluate the effects of each treatment process. The results indicated the existence of frame shift mutagens in the source water in Beijing, but not base pair substitute mutagens. Prechlorination, coagulation and chlorination may cause mutagenic effects to increase, while coal-sand filtration and granular activated carbon adsorption may remove most of the mutagens formed. Similar conclusions were drawn from the acute toxicity assay.