Staff members of the local quality supervision bureau empty tainted milk power packets at a garbage dump site in Shenzhen, Guangdong province September 19, 2008. Nearly 10 percent of milk samples from three top Chinese dairy companies has been tainted with toxic melamine, the government quality watchdog found in tests for the banned chemical that has killed four children. REUTERS/Stringer (CHINA). CHINA OUT. NO COMMERCIAL OR EDITORIAL SALES IN CHINA.