The age dependence of the natural concentration of uranium and thorium in the skeleton was investigated using human vertebrae bone collected from two Canadian locations (Winnipeg, Manitoba, and Regina, Saskatchewan). The concentration of both radioelements in digested ashed bone samples was determined using sector-field inductively coupled plasma mass spectrometry. The geometric means for uranium level in bones showed a significant statistical difference between the two locations studied. Similarly for thorium, a statistical difference was observed, although this difference was considered marginal. The thorium concentration differed only marginally with respect to age group, indicating that its behavior in the body could be age-independent. Conversely, the uranium level in bones was found to change for the age groups tested, an indication of age-specific deposition. The age profile for uranium was comparable to the calcium turn-over rate, indicating that uranium deposition is probably, in part, dictated by this metabolic process, showing the role of present uptake into the uranium concentration in bones for populations exposed to significant uranium intake.
* Radiation Protection Bureau, Health Canada, 775 Brookfield Road, Address Locator 6302D1, Ottawa, ON, Canada, K1A 1C1; † Environmental Health Science Bureau, Health Canada, Environmental Health Center, Tunney's Pasture, Address Locator 0801A, Ottawa, ON, Canada, K1A 0K9.
For correspondence contact: Dominic Larivière, Radiation Protection Bureau, Health Canada, 775 Brookfield Road, Address Locator 6302D1, Ottawa, ON, Canada, K1A 1C1, or email at firstname.lastname@example.org.
(Manuscript accepted 7 July 2006)