The authorities yesterday set standards for melamine levels in milk and associated food products to allay¹ fears following a contaminated milk powder scandal.

The limits were set at 1 mg per kg for infant formula, and 2.5 mg per kg for other dairy products including liquid milk, according to a joint² statement issued by five government agencies including the Ministry³ of Health.

Melamine, used in products including plastics, paint and adhesives⁴, can lead to kidney stones and other urinary tract⁵ problems. The chemical has been blamed for the deaths of at least four babies, and more than 54,000 children have fallen ill after being fed milk formula tainted⁶ with melamine.

There had been no previous standards, and levels of melamine discovered recently in batches⁷ of contaminated milk powder made by Sanlu Group registered as much as 2,563 mg per kg.

Wang Xuening, an official with the health ministry, told a press conference yesterday that it is almost impossible to keep the melamine level at zero as small amounts of the chemical can leak from packaging into milk and other food products. But he warned that "deliberate tainting⁸ is explicitly⁹ forbidden".

"Those who add melamine to food products will bear legal responsibility," he said.

Chen Junshi, a researcher at the Chinese Center for Disease Control and Prevention, said the limits will "help inspectors¹⁰ assess whether melamine was deliberately¹¹ added".

"If the amount exceeds 1 mg per kg, we have reason to believe it was intentionally¹² added."

Some dairy suppliers have been found to add melamine to milk to make it appear protein-rich in tests.

Health authorities said the new limits are in line with international standards, and recognized by the World Health Organization and the UN Food and Agriculture Organization.

The US Food and Drug Administration (FDA) said last week that 2.5 mg of melamine per kg would not cause health problems but added that any infant formula sold to the US must be free of melamine.

Standards in Hong Kong and New Zealand also set a safe melamine limit in food products of 2.5 mg per kg, though Hong Kong has lowered the level for children under 3 and pregnant or lactating women to 1 mg per kg.

Meanwhile, China's food safety watchdog said yesterday no traces of melamine were found in the latest round of tests of milk powder sold domestically.

The tests were carried out on 316 batches of milk powder of 54 brands produced after September 14, the General Administration of Quality Supervision¹³, Inspection¹⁴ and Quarantine said on its website.

It was the fourth time in less than a week that the food safety regulator said tests of dairy products showed no melamine contamination.