Briefly talk about Sanlu milk powder incident (about 100 words)

After investigation by relevant departments, Sanlu milk powder was caused by the addition of melamine by criminals in the process of purchasing raw milk. As for whether melamine was also added in the production process, Mao Qunan, a spokesperson for the Ministry of Health, said that it is still uncertain and is still under investigation. Many children have kidney disease after eating the problem milk powder. Now children who have eaten the problem milk powder can have a free physical examination and return the milk powder!