Asbestos is a mineral that reaches the water supply due to decay of asbestos cement water mains and pipes, asbestos-containing filters, as well as the erosion of natural deposits. Workers exposed to large continued doses of asbestos can contract asbestosis, a disease that creates scar tissue in the lungs, heart enlargement, and even lung cancer and death. Prolonged consumption in low doses can increase the risk of developing benign intestinal polyps and is a known human carcinogen.