A tourist drinks water from a direct drinking water facility in Suzhou Garden Museum on August 28, 2014. [Photo/Suzhou Evening News]

For residents in East and South China, the safety of their drinking water has become a big concern, as the drinking water in 44 cities of the 23 provinces in these regions has been found to contain nitrosamine, according to a report based on a three-year investigation by the School of the Environment at Tsinghua University.

It is thought that nitrosamine may be a cause of cancer in the human digestive system. One of the experts involved in the study said that nitrosamine is quite like PM2.5, the particles less than 2.5 microns in the air that are harmful to people's respiratory systems.

Although further investigation is still needed to find out the relationship between the chemical and stomach cancer or other cancers of the digestive system, the results of the study serve as a reminder that much still needs to be done to make sure that our water is safe to drink.

China has no standard for the amount of nitrosamine in its drinking water. Some experts were quoted as saying that most of the drinking water in China is within the required World Health Organization standard when it comes to nitrosamine, but if it is judged by the standard of the State of California in the United States, the nitrosamine levels found in the drinking water of the 44 cities are much more than is permitted.

What is particularly thought-provoking is the fact that the highest levels of nitrosamine were found in the drinking water of the economically developed Yangtze River Delta, where residents are wealthier and enjoy better living standards than in other parts of the country.

This may be the price the country is paying for the lack of attention paid to checking the discharge of pollutants as the economy boomed in the past more than three decades.

The report published by the study group emphasizes that contamination of ground water is a pressing issue. It is quite common for ground water to contain ammoniacal nitrogen, nitrites and nitrates in areas around farmland and chemical plants.

Whether or not the nitrosamine found in drinking water proves to be as harmful as the PM2.5 in the air, there is no reason for the central and local governments to drag their feet in their efforts to protect the ground water from being contaminated and treat the ground water that has already been polluted.