A shopper chooses Yili's baby formula milk powder in Henan province on May 26, 2012.[Photo/Asianewsphoto]

Inner Mongolia Yili Industrial Group, one of China's biggest dairy product manufacturers, suffered a setback when batches of baby formula were found to contain excessive mercury.

The company is recalling all formula milk powder for infants in the Quanyou 2, 3 and 4 series produced from November 2011 to May 2012, according to a statement on the company's website.

The recall came after samples of those batches were tested with abnormal mercury content on June 12 by food safety inspectors.

"At present, the country has no standards on mercury limits in milk powder. But to be responsible to consumers, the company decided to recall all related products," said the statement.

Wang Dingmian, former vice-chairman of the Guangdong Dairy Association, told China Daily that the country permits no more than 0.01 milligrams of mercury per kilogram in raw milk.

"It is inevitable that mercury may pollute milk products via air, water, soil and even during the process of packing. Therefore, limited standards of mercury are also needed to set up targeting for milk powder as soon as possible," he said.

"We received a notice from Yili to pull its products from its Quanyou series from the shelves about two months ago, but I do not know the reason," Zhang Shaoru, a saleswoman in a Wu-Mart supermarket in Beijing, said on Thursday.

Products of the Quanyou series are cheaper than other Yili milk powder products, but always sold well, she said.

Wu Guangchi, a child nutrition professor at the Capital Institute of Pediatrics, said that at present it is rare to see mercury poisoning from food.

"Mercury poisoning is always coming from environmental pollution, for instance, nearby industrial and mining regions. Some such poisoning is also triggered by substandard cosmetics," he said.

According to Wu, mercury poisoning can damage the brain, kidney and liver.

For adults, intake of 0.3 grams of mercury will cause death, while 0.1 grams will kill a child, he said.

The General Administration of Quality Supervision, Inspection and Quarantine said in an urgent notice on Thursday that it launched a test on 715 samples from all infant milk powder brands in Chinese market, and no sample shows abnormal in mercury content except that from Yili.

Wang Qingyun contributed to this story.

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