Strontium

Radioactive strontium isotopes, such as Sr 90 – produced by the nuclear fusion of Uranium – can lead to various bone disorders and diseases, including bone cancer.
Strontium is absorbed into the body as though it were calcium, as the two are chemically very similar. The stable forms of strontium (4 of the 20 isotopes are stable) does not seem to pose a significant health threat and may actually be beneficial. A recent study showed that the use of strontium on osteoblasts showed marked improvement in bone building (bone density) on patients. However, high levels of Strontium have also been found in patients with osteoporosis.