Can­cer agent found in 44 cities’ drink­ing wa­ter

Con­tam­i­na­tion is a ‘press­ing is­sue’, ex­pert says; no na­tional stan­dards for level yet

China Daily (USA) - - CHINA - By SHAN JUAN shan­juan@chi­nadaily.com.cn

Traces of a po­ten­tially can­cer-caus­ing chem­i­cal known as NDMA was 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 anew­study.

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. Theav­er­ageNDMA­con­cen­tra­tions— 11 ng per liter for fin­ished wa­ter, and 13 ng per liter for tap wa­ter — is nearly four times what was re­ported in theUnited States in 2012.

The two fig­ures reached 27 ng/L and 28.5 ng/L in Yangtze River Delta ar­eas, pos­ing a di­ges­tive can­cer risk for res­i­dents there, lead re­searcher ChenChao, an as­so­ciate professor at Ts­inghua Univer­sity’s School of En­vi­ron­ment, was quotedas say­ing­byS­cience­and Tech­nol­ogy Daily on Friday.

“TheNDMA­con­cen­tra­tionin drink­ing wa­ter is a press­ing is­sue that de­mands more re­search and sys­tem­atic mod­i­fi­ca­tions,” he said.

NDMA and other ni­trosamines cause can­cer in lab­o­ra­tory an­i­mals, ac­cord­ing to the World Health Or­ga­ni­za­tion. ChenWan­qing, > p11 Cur­rently, the sub­stance is not reg­u­lated as a drink­ing wa­ter qual­ity stan­dard in China. No max­i­mum­level has been set.

Chen said it may be in­cluded soon as a stan­dard for wa­ter safety.

The WHO sets a cap on NDMAin drink­ing wa­ter at100 ng/L. The stan­dard in Canada is 40, while in Aus­tralia it’s 100.

The states of Mas­sachusetts andCal­i­for­nia in theUSre­quire a stricter stan­dard— 10 ng/L.

“In­dus­trial and sewage con­tam­i­na­tion might be blamed for high lev­els,” Chen said.

Chen Wan­qing, di­rec­tor of the Na­tional Cen­tral Can­cer Reg­istry, con­firmed a link be­tween ni­trosamines and hu­man can­cers, but stressed that can­cer would be only caused by high lev­els.

“The trace found in the wa­ter can­not lead to can­cer via drink­ing tap wa­ter,” he said. Also, boil­ing tap wa­ter fur­ther low­ers the NDMA con­cen­tra­tion.

NDMAhas also been de­tected in foods such as pick­les, cured fish and to­bacco smoke, he said, adding that un­like heavymet­als, NDMAis un­likely to ac­cu­mu­late in the body.

The trace found in the wa­ter can­not lead to can­cer via drink­ing tap wa­ter.” di­rec­tor of the Na­tional Cen­tral Can­cer Reg­istry See See ed­i­to­rial>ed­i­to­rial

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