First, a dredge is a device used to scrape or to suck from the seabed. This is where the term dredging comes from. There are many toxic substances found in dredge that would be released upon dredging the river bottom. The toxins have been associated with many different health problems. The substances and problems are as follows: Aluminum is associated with Alzheimer's, Parkinson's and Lou Gehrig's diseases and also can cause sperm and testicular abnormalities. Arsenic affects skin, peripheral nerves, and vascular system, while also affecting male/female birth ratio, abortion potential, and increases the risk of cancer. Cadmium is a carcinogen which attacks the kidneys and bone structure. Lead affects the central nervous system by causing disorders in children, while also affecting kidneys, immune and reproductive systems. Maganese at high levels can cause low energy, muscle malfunction, tremors, mental disorders, and is associated with Parkinson's disease along with worsen an existing condition. Mercury also attacks the central nervous system along with the kidney and gastrointestinal systems. Vanadium will destroy intestines, liver, and lungs while also affecting the vascular system. These toxins could possibly leak into the water supplies affecting an entire community. The toxins come from pollution before laws were enacted prohibiting this type of action. Another action takes place when the dredge is disturbed from the river bottom and that is the toxins will be released into that same water supply. These toxins will also be harmful to all species found in the vicinity just as with humans. These toxins will also follow with the flow of water and cause pollution in those areas as well.