Milk from some of China's biggest dairies has been found to contain poisonous melamine, prompting authorities to clear shelves of dairy products, in addition to the earlier recall of tainted infant formula, the BBC reports. A watchdog group found the banned chemical in 10% of samples from three dairies, including the two largest. Milk suppliers are suspected of diluting milk and then adding melamine to make the protein content appear higher.
The industrial chemical, normally used in plastics, was discovered in milk powder that sickened 6,000 infants and killed at least four. No illnesses have been reported from drinking tainted liquid milk. Foreign importers of milk products have pledged not to take advantage of the huge recalls by raising prices.