People always put waste batteries everywhere. There is a question, whether these waste batteries do harm to human? Battery works on chemical reactions. So it contains many heavy metals, such as cadmium, mercury, manganese. These heavy metals will leak out after a long time. Some will enter into the soil and absorbed by vegetation. When we eat these vegetation, these heavy metal will enter into our body and do harm to our nerve system, hematogenic system, kidney and bones. Some even can cause cancers. So the best way to solve this problem is to recycle these waste batteries and reuse them.