SHANGHAI - Prosecutors in this city's Songjiang district have approved the formal arrest of two men suspected of dumping acid directly into a river and causing severe pollution.

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The two suspects, surnamed Jiang and Dong, dumped 60 tons of waste acid into the Honghe River in the Songjiang district between February and March. They are the first suspects arrested for an environmental pollution offense after new rules contained in Amendment VIII to the Criminal Law were enacted on May 1.

Since 2009, Jiang, 55, had been entrusted with disposing and recycling waste acid produced by six chemical companies. The companies paid him from 50 yuan to 55 yuan ($7.7-8.5) for each ton of the waste he collected.

Dong, 26, was hired by Jiang to drive a tanker vehicle carrying the waste. In February 2011, Jiang asked Dong to start pouring the waste directly into the Honghe River so he could avoid the costs he would incur by recycling it. The contamination subsequently killed large numbers of underwater creatures and gave the river a stench.

A resident reported to police in mid-February that he had found dead fish floating in the river and that the color of the water had turned rusty. On March 27, Songjiang police caught Jiang and Dong in the act of pouring the waste acid into the river.

The illegal dumping has caused the 2,000-meter water channel to be severely polluted, according to examination reports from the Shanghai Solid Waste Management Center and Shanghai Environmental Science Research Institute.

Preliminary estimates hold that cleaning up the river will cost about 1.78 million yuan, according to environmental protection authorities in Shanghai.

Jiang and Dong told police they dumped the waste acid into the river simply to avoid spending money. They said they did not suspect, at the time of the dumping, that what they were doing would prove so harmful.

Prosecutors said Jiang and Dong dumped the acid at night on several occasions, and that they knew their acts were in violation of the law and were harmful to the environment.

Prosecutors learned that neither Jiang nor Dong is licensed to transport or recycle waste acid. The six chemical companies that gave the acid to Jiang and Dong did so to avoid spending money on recycling and without investigating whether the two suspects were qualified to deal with such waste.

In the past, the perpetrators of such acts could not be convicted as criminals unless their misdeeds had either caused serious harm to public or private property or injuries or deaths.

Under the new environmental rules, anyone who releases, dumps, or disposes of radioactive wastes, wastes containing pathogens, toxic materials or other dangerous wastes into the land, water or atmosphere will be held responsible as a criminal, according to Zhou Xiaqin, prosecutor in charge of the case.

It is now easier to prove that a polluter has committed a crime, Zhou said.