Cadmium dangers long known
This is not the first time people have been poisoned by cadmium. The problem was first documented in Japan's Toyama prefecture in the 1930s when people complained of spinal and joint pain.
Nor are the people of Zhentou the only ones in Hunan to have been poisoned by the heavy metal, which causes digestive and other problems. Three years ago at least eight people died of cadmium poisoning and more than 1,000 others were made ill in Majiahe, Zhuzhou .
Two years ago, nearly 100 workers at a plant in Wuxi , Jiangsu , making liquid crystal displays for Japanese electronics giant Panasonic suffered cadmium poisoning.
And in 2004, workers from two battery-making plant in Huizhou , Guangdong, took Hong Kong-listed Gold Peak Industries to court claiming they were among more than 100 poisoned by cadmium. The company denied they were poisoned, but paid compensation to more than 1,000 for cadmium-related illness.
Doctors say cadmium can damage the intestinal tract and cause cancer.