BEIJING, Oct. 8 (Xinhua) -- China's Health Ministry has issued new safety standards for dairy foods following the scandal of melamine-contaminated milk products that sickened thousands of babies.

　　The industrial chemical was intentionally added to diluted milk to make it seem high in protein content. More than 50,000 babies were sickened as a result of consuming contaminated milk powder.

　　At a press conference on Wednesday, Wang Xuening, deputy director of the ministry's Health Supervision Bureau, released new rules for the dairy industry.

　　Wang said a maximum of one milligram of melamine per kilogram of infant formula was the new limit.

　　A maximum 2.5 milligrams per kilogram was allowed for liquid milk, milk powder and food products containing at least 15 percent milk.

　　"Melamine is neither a raw food material nor a food additive," he said. "Deliberately adding the chemical to food items is prohibited. Once such cases are spotted, they will be investigated according to law."

　　Melamine is used to make plastics and food packaging materials. When asked why China allowed any melamine at all dairy products, Wang said it was impossible to have "zero levels". The chemical can seep into food from its packaging.

　　"The limits mainly aim to curb the deliberate adding of melamine," he said.

　　According to the standards of the Unites Stated Food and Drug Administration, the safety reference value (tolerable daily intake, or TDI) for melamine is 0.63 milligrams per kilogram of body weight per day.

　　A child weighing 30 kilograms would have to drink around 1.2 kilograms of milk powder containing 15 milligrams of melamine per kilogram a day to have exposure reaching the TDI.

　　In tests by China's quality watchdog, the State Administration of Quality Supervision, Inspection and Quarantine (AQSIQ), last month, Sanlu products had the highest content of melamine, at 2,563 milligrams per kilogram, out of the 109 baby formula producers tested.

　　The Sanlu Group, a leading dairy producer based in the northern Hebei Province, admitted on Sept. 12 it had found some of its baby milk powder products were contaminated with melamine.

　　Contaminated baby formula has killed at least three infants and left more than 53,000 with urinary tract problems, including kidney stones. About 13,000 infants are still being treated in hospitals.

　　So far, 27 people have been arrested over the scandal.