Five people have been arrested over a Chinese company's illegal dumping of carcinogenic industrial chemicals in Yunnan province, which led to widespread water pollution in the area and animal deaths.

The suspects include two employees of the chemical company that produces the toxic waste, and two carriers. Rainfall in June washed some of the chromium into local water supplies, causing 77 cattle to die.

Chen Jun, vice mayor of Qujing City, Yunnan province, said, "The dumping site was comparatively far from drinking water sources. So far we haven't found any impact on local residents' water safety."

The vice mayor pledged to deal with the decontamination in an earnest way. Measures taken include restoring the polluted soils and monitoring the local river. The companies involved have been requested to halt operations. Any direct losses to local residents are being compensated by the local government.

Chen Jun, vice mayor of Qujing City, Yunnan province, said, "The indirect economic loss is being assessed by local environmental organizations."

But the impact was not confined to this county, or Yunnan province. As the water runs into the Pearl River, one of China's longest waterways, the pollution scandal has sparked fears among millions of residents living downstream.

As a result, the case has received much attention from the national environmental watchdog, which says such cases are by no means isolated to Yunnan.

Zhang Lijun, vice minister of Ministry of Environmental Protection, said, "There are over 100 pollution cases caused by chromium residue. The total pollution area is around 50 thousand square kilometers. The chromium level on some polluted ground is 100 times higher than the safety standard."

A national campaign is now looking for companies that deal with hazardous waste to publish annual environmental reports and for harsher penalties to be imposed on those who pollute.