BEIJING (AP) — China today introduced standards for levels of the industrial chemical melamine permitted in milk and food products as it seeks to rein in a festering safety scare.

The government has been struggling to deal with health and public relations issues stemming from the scandal, which is increasingly affecting China’s food exports.

The deaths of at least four babies in China have been blamed on the chemical and more than 54,000 children have been sickened.

Wang Xuening, a Health Ministry official, on Wednesday acknowledged that small amounts of melamine can leech from the environment and packaging into milk and other foods, but said that deliberate tainting is explicitly forbidden.

“For those who add melamine into food products, their legal responsibility will be investigated,” said Wang, deputy director of the ministry’s health supervision bureau.

Safe melamine limits were set at 1 part per million of infant formula and 2.5 parts per million for liquid milk, milk powder and food products that contain more than 15 percent milk.

Chen Junshi, a researcher for China’s Center for Disease Control and Prevention, characterized the limits as a measure for inspection.

“They will help assess whether melamine was intentionally added,” Chen said. “If the amount exceeds one milligram (one part per million), we have reasons to believe it was intentionally added. If the amount is below one, it’s very likely that it is because it existed in the environment.”

There had been no previous standards and levels of melamine discovered in batches of milk powder recently registered as much as 6,196 parts per million. Chinese health officials have said no harm comes from consuming less than 0.63 parts per million.

Guidelines in Hong Kong and New Zealand say melamine in food products is considered safe at 2.5 parts per million or less, though Hong Kong has lowered the level for children under 3 and pregnant or lactating women to one part per million.

In the United States, the Food and Drug Administration said last week that its experts have concluded that eating 2.5 parts per million of melamine — a minuscule amount — would not raise health concerns, even if a person ate food every day that was laced with the chemical.

Brazil on Tuesday became the latest of dozens of countries to restrict Chinese food products. It banned all such imports because of safety concerns.

Brazil’s food imports from China are minimal — in 2007 the country bought just US$120 million in such products.

The Philippine health secretary said Wednesday that traces of melamine have been found in a third imported Chinese-made milk product, Jolly Cow Slender Milk, which had already been taken off shelves.

China’s Cabinet has already acknowledged that the country’s dairy industry was “chaotic” and suffered from a grave lack of oversight. It has pledged to monitor milk products from dairies to store shelves.

The State Council has also ordered hospitals to provide free treatment for sick infants,

The crisis has forced the government to fire local and even high-level officials for negligence, while repeating earlier promises to raise product safety standards.