The food and drug authority in Guangzhou, Guangdong Province, Saturday night named rice producers whose products were found to be tainted with excessive amounts of cadmium, according to its website.

The move by the Guangzhou Food and Drug Administration came after public demand for the information. Of 18 batches of rice tested during random quarterly checks, eight were found to contain excessive amounts of the heavy metal. The metal is known as a strong carcinogen, and can cause pathological changes in the kidneys and other organs.

The names of the producers of the eight substandard batches were released late Saturday. Six are in Hunan Province, while two others are in Dongguan. 

However, an administration press officer told China National Radio on Saturday that the range of tested products was narrow, so the results do not represent the overall situation in Guangzhou.

The administration said earlier that only the release of data is allowed, in a response to public questioning over the opaque information made public on Thursday, which did not reveal the name or location of the producers.

Chen Xiao'an, a student at the Guangdong University of Foreign Studies, who wrote to the authority to push for the disclosure on Friday, said it is absurd that after testing the products, they failed to tell the public the brand names, reported the Guangzhou-based Nandu Daily.

The administration then released on Friday where the tainted rice was found, including two local colleges' canteens and two other eateries. Some 0.21 to 0.4 milligrams of cadmium was found per kilogram of rice, surpassing the national limit of 0.2 milligrams.

"It's common that the information should be disclosed, authorities have been doing this," Liu Xinwu, a Jiangsu-based food safety lawyer told the Global Times, adding that the public's demand for disclosure is reasonable.

The Global Times found that most of the previous test results posted on the administration's website did have the manufacturers' information included.

Contaminated rice has been a long-lasting problem. A Nanjing Agricultural University research project in 2011 found that around 10 percent of rice sold across the nation contained excessive amounts of cadmium.

Sun Wenjie, a food safety lawyer from Yunnan Province, told the Global Times that the food safety information that is of paramount concern to consumers is required to be made public in a timely manner, as is stipulated in the country's regulations on information disclosure.

"Cadmium in rice usually comes from the soil where it grows, and the soil was polluted by mining and chemical wastes," Fan Zhihong, a food safety expert at China Agricultural University in Beijing told the Global Times.

"I don't think they (Guangzhou authorities) meant to cover something up," Fan said. "The public's attention to this issue at least shows they are more environmentally aware, which is good."