Some 10 percent of rice sold in China is contaminated with cadmium, a chemical that leads to softening of the bones and kidney failure, Beijing-based Century Weekly magazine reported Monday.

The substance was mostly detected in rice produced in southern parts of China including Jiangxi, Hunan and Guangdong provinces, the report said.

The report highlights a prominent but ongoing problem of Chinesesoil being polluted with heavy metals discharged from massive mining operations and other industrial activities over the years.

Other chemical substances including lead have also been detected in rice, the report said, citing a study by Nanjing Agricultural University.

"Rice is the main food in Chinese people's diets, but not many people pay attention to the serious problem of heavy metal contamination in rice," Zeng Xibo, a researcher from the Chinese Academy of Agricultural Sciences, told the Global Times.

The report said dozens of residents in Sidi village, Yangshuo county, the Guangxi Zhuang Autonomous Region, where cadmium pollution is heavy, are suspected of having the symptoms of itai-itai disease, which is characterized by pain in the joints and the spine.

The report cited statistics from the Guilin Institute of Technology showing that the level of cadmium was 1.005 milligrams in every kilogram of locally grown rice in 1986, five times the standard amount.

Zeng said the most effective way to restrict the pollution was to control industrial discharge, as the cadmium came mainly from the heavy metal industry.