U.S. Blocks Chinese Milk Products Federal food safety officials yesterday began holding up shipments of food from China that contain milk or milk-derived ingredients in the largest effort to date to keep products tainted with the industrial chemical melamine from reaching U.S. consumers. The Food and Drug Administration is requiring importers of the halted shipments to test for the chemical, which is used to make plastic and fertilizer but has been added to human and animal food to boost protein readings. The types of products likely to be waylaid are cookies, candies, and other goods made with milk or milk powder. If an importer can prove his product is not tainted, FDA will release it, said Steve Solomon, the agency's deputy associate commissioner for compliance and policy. The agency also will step up its testing of products already on the market....