Others, like melanoma, are much more dangerous because they spread to other parts of the body. Deaths due to melanoma are increasing by 4 percent each year. In the 1930's, health experts noticed that people who lived in areas where the water contained natural chemicals called fluorides had fewer cavities. Today, nearly half of all Americans drink water that is either naturally fluoridated or treated with fluorides. This has lowered the incidence of cavities as much as 65 percent.
Dentists can also protect young teeth by applying special coatings called sealants.
Uranium Poisoning Uranium is a dangerous element because it is radioactive. This means it gives off high-energy particles that can go through the body and damage living tissue. A single high dose of radiation can kill. Small doses over a long period can also be harmful. For example, miners who are exposed to uranium dust are more likely to get lung cancer.