Chinese authorities have found more milk products contaminated with the toxic industrial chemical melamine. Of the three companies whose products were found containing the deadly chemical, one was linked to an earlier milk scandal in which six children died and hundreds of thousands were made ill. Most of the sick were affected by drinking baby formula milk powder. Over a dozen stores were found to be selling the contaminated milk, and officials say some of the milk may have been recalled by the earlier scandal, yet found its way back onto store shelves. Melamine, which can cause kidney failure if ingested by humans, is normally used in the manufacture of plastics and fertilizer. It is used to disguise milk that has been watered-down by making the diluted milk appear to contain more protein than it actually does in quality control tests. Dozens of officials were punished following the 2008 tainted milk scandal; two were sentenced to death.