Cancer agent found in 44 cities’ drinking water

Traces of a potentially cancer-causing chemical known as NDMA were detected in the drinking water of 44 Chinese cities, while samples from the east and south were found to have relatively high concentrations, according to a new study.

Measured in nanograms per liter, NDMA — short for N-nitrosodimethylamine — is a byproduct of the disinfection process used for chlorinating drinking water and is considered an “emerging contaminant”, together with other related chemicals known as nitrosamines.

Samples were taken from 155 sites in 44 cities across 23 provinces, including original sources, finished water from treatment plants and tap water. The average NDMA concentrations — 11 ng per liter for finished water, and 13 ng per liter for tap water — is nearly four times what was reported in the United States in 2012.