Strontium-89 has the same chemical properties as strontium-90 and will follow the same metabolic paths. quantities than strontium-90. It is created in much larger However, it has a shorter half-life (53 days) and emits beta particles with about one-half the energy of those from strontium-90. For these reasons strontium-89 content in milk may peak at values many times that of strontium-90 during the periods immediately following nuclear tests, yet the total radiation dose to the bone over a lifetime from strontium-89 may be only one-quarter that of strontium-90!-. the Data ~ About 21 million curies of strontium-90 have been created by atmospheric nuclear tests with about 17 million curies of this being spread globally. The other 3 million curies fell quickly in areas local to the testing sites. To dete, roughly 8-9 million curies of strontium-90 have been deposited globally, leaving a calculated 6 million curies in the region of the atmosphere below 100,000 (based pot on measurements using aircraft and balloons) and one million curies above this level - estimated by extending the observed datal3-. The discrepancy in total numbers is due in part to radiological decay of strontium-90 but more because of uncertainties in the estimates themselves. As expected, the peak value of "strontium units" in milk was passed in June of 1963 (32 "strontium units" as a national average) !4-, In the absence of atmospheric tests these levels are expected to continue te