Some 10,000 tons of cadmium-tainted rice from Hunan Province was reported by the Guangzhou-based Nanfang Daily Wednesday to have found its way onto the market in Guangdong Province, a claim that had been denied by some of the companies named in the report.

Some of the rice, which far surpassed the State level of 0.2 milligrams of cadmium per kilogram, was reported to have been transported and sold in Guangdong by the Shenzhen Cereals Group in 2009.

The report said after discovering the excessive cadmium levels the Shenzhen group forced several national grain reserves to slash their prices. The group earned a huge profit when it resold the rice when the market peaked without telling buyers it was contaminated, said the report.

In a statement released Wednesday, Shenzhen Cereals said it had "returned all the cadmium-tainted rice and none of it entered the market."

"The 13,584 tons of tainted rice was part of 15,415 tons purchased from Hunan, and it was immediately segregated," said the statement.

The mandatory State standard, which took effect in 2005, stipulates that rice with excessive levels of cadmium can only be used for industrial purpose such as ethanol products.

The Guangdong Provincial Center for Disease Control and Prevention said cadmium-tainted rice is carcinogenic, as the heavy metal can remain in the human body for 30 years. It can also trigger Itai-itai disease, named after Japanese villagers who suffered severe pain in their joints and spine.

The Guangzhou Zhujiang Brewery, which was also named in Wednesday's newspaper report, said it was impossible for its beer to contain excessive levels of heavy metal because of the stringent quality check it carries out.

The report suggests that the brewery has used the contaminated rice to brew its beer.

The newspaper said that an "all-safe" inspection report can be illegally obtained for a 5,000 yuan ($802.5) under-the-table payment. The Hunan provincial grain authority declined to comment when reached by the Global Times Wednesday.

The Hunan Provincial Academy of Agricultural Sciences said cadmium contamination is caused by many factors including climate, soil and the water used for irrigation.

Chen Tongbin, a researcher with the Institute of Geographic Sciences and Natural Resources Research of the Chinese Academy of Sciences, said there are likely 5.36 million hectares of cadmium-tainted farmland in the country.

Pan Genxing, a professor from the Institute of Resource, Ecosystem and Environment of Agriculture with Nanjing Agricultural University, estimated that some 10 percent of the country's annual output of rice, or 20 million tons, especially crops from Hunan and Jiangxi provinces, contains excessive levels of cadmium.