Water pollution by chemical elements which can get there to discharges of industrial wastewater lead to dangerous and intractable diseases. For example, mercury or cadmium, cause specific diseases: меркуриоз (Minamata disease), characterized by impaired hearing, sight, touch, neurological disorders; and кадмиоз (disease Itay - Itay) when there are strong pain, deformation of the skeleton, kidney, skeletal fractures.
There are special services that control the situation reservoirs. They put penalties enterprises are closed. But it's not enough to each person felt responsible for their actions...