Write about how the strontium-90 might accumulate in your body (teeth and bones) and how it might affect you. Include your ideas about how its half-life of 28.8 years would be important. Suggest ways that government agencies, such as your state’s department of health, might test for strontium-90. Where in your environment might scientists look for large concentrations of strontium?

• Strontium-90 is the most important radioactive isotope in the environment
• 1790 Adair Crawford and William Cruikshank found non-radioactive strontium in the mineral strontianite in Scotland.
•  Metallic strontium in 1808 by Sir Humphry Davy
• Strontium (chemical symbol Sr) is a silvery metal that rapidly turns yellowish in air. .
• Strontium has 16 known isotopes. Naturally occurring strontium is found as four stable isotopes Sr-84, -86, -87, and -88.
• Strontium-90 is chemically similar to calcium, and tends to deposit in bone and blood-forming tissue (bone marrow). Thus, strontium-90 is referred to as a "bone seeker." Internal exposure to Sr-90 is linked to bone cancer, cancer of the soft tissue near the bone, and leukemia.
  Risk of cancer increases with increased exposure to Sr-90. The risk depends on the concentration of Sr-90 in the environment, and on the exposure conditions.

http://www.epa.gov/radiation/radionuclides/strontium.html#healtheffects