What are heavy metals?

In terms of environmental pollution, heavy metals refer to heavy metals, such as mercury, cadmium, lead, chromium and arsenic.            

There are 5 kinds of poison to human body: lead, mercury, chromium, arsenic and cadmium. These heavy metals ca not be decomposed in water. After drinking, they are amplified by toxicity and combined with other toxins in water to produce more toxic organic or inorganic substances.