Three rice mills in Central China's Hunan province are being investigated after rice they produced was found to be contaminated with cadmium last week, local authorities said on Tuesday.

The mills in Zhuzhou's Youxian county were ordered to recall their products and halt business operatons, the county government said.

Samples of the rice stored in the mills have been sent to the provincial quality inspection agency for examination.

The government said the mills had been operating legally and that all of the tainted rice had been collected from local farmers.

A food safety inspection in the first quarter of the year showed that 44.4 percent of rice and rice products in the city of Guangzhou, Guangdong province, contained excessive cadmium, a carcinogenic industrial chemical, Guangzhou's Food and Drug Administration said on Thursday.

The administration said eight samples from the 18 batches of rice and rice products tested positive for cadmium contamination.

Cadmium-tainted rice and rice products have been found in two university cafeterias and two restaurants, the food safety watchdog reported on Friday.

The suppliers of five of the contaminated batches come from Youxian. Another three contaminated batches came from Hengyang, in Hunan, and Dongguan, in Guangdong.

More tainted rice and rice products were also found in the Shunde district of Foshan, Guangdong province, the Nanfang Daily reported on Tuesday.

Inspectors found nine batches of tainted rice during a district-wide inspection campaign.

The rice that contained cadmium was discovered in Lecong, Leliu, Xingtan and Beijiao townships.

Inspectors in Shunde have sealed up to 20 kilograms of the tainted rice for further investigation and asked rice retailers and companies to recall another 3,513 kilograms of tainted rice.

Experts believe that the soil in some rice-producing areas has been contaminated by heavy metals, which in turn has polluted water sources. Zhuzhou and Hengyang are industrial cities along the Xiangjiang River in Hunan.

Hou Yanlin, an Agriculture Ministry soil scientist, said the government should establish a monitoring and early warning system for soil contamination so that it can evaluate how severe and widespread the pollution is.

Hou said soil pollution control legislation is urgently needed.

Gao Shengda, secretary-general of the China Environmental Remediation Industry Alliance, said the nation must develop targeted soil remediation techniques and bring in advanced technology from overseas.

The experts warned that because some fertilizers and pesticides can cause heavy metal pollution, the use of such chemicals should be reduced or avoided altogether.

(China Daily 05/22/2013 page5)