Beijing announced limits on Wednesday for the amount of melamine permitted in dairy products, the South China Morning Post reported. The Ministry of Health stressed that melamine, which has killed at least four babies in China, should not be tolerated at all and that the limits had been introduced to aid regulators. According to the provisional rules, infant milk formula should contain no more than 1 part per million of melamine, while products not targeted at babies should contain no more than 2.5 parts per million. The World Health Organization says an adult weighing 50 kilograms can tolerate only 25 milligrams of melamine per day, and a baby weighing 5kg could cope with up to 2.5mg per day. According to Chen Junshi, a senior researcher at the National Institute for Nutrition and Food Safety, a small amount of melamine was allowed in baby milk products because the chemical is widely used in packaging.