Thirteen female Rhesus macaques were intramuscularly injected with 90Sr(NO3)2 diluted in sodium citrate solution. The biokinetic data from these animals were compared against the predictions of the NCRP 156 wound models combined with the ICRP systemic models. It was observed that the activities measured in plasma of these nonhuman primates (NHPs) were consistently lower than those predicted by the default human biokinetic models. The urinary excretion from the NHPs at times immediately after injection was much greater than that in humans. The fecal excretion rates were found to be in relatively better agreement with humans. Similarly, the activities retained in the skeleton of the NHPs were lower than those in humans. These differences were attributed to the higher calcium diet of the NHPs (0.03 to 0.12 g d−1 kg−1 body weight) compared to that of humans. These observations were consistent with the early animal and human studies that showed the effect of calcium on strontium metabolism, specifically urinary excretion. Strontium is preferentially filtered at a much higher rate in kidneys than calcium because it is less completely bound to protein than is calcium. These differences, along with large inter-animal variability, should be considered when estimating the behavior of strontium in humans from the metabolic data in animals or vice versa.
*Radiation Protection Division, Los Alamos National Laboratory, Los Alamos, NM 87545; †Lovelace Respiratory Research Institute, Albuquerque, NM and Ray Guilmette and Associates, LLC, Perry, ME; §Department of Nuclear Engineering and Health Physics, Idaho State University, Pocatello, ID.
The authors declare no conflicts of interest.
For correspondence contact: Deepesh Poudel, Radiation Protection Division, Los Alamos National Laboratory, Los Alamos, NM 87545, or email at firstname.lastname@example.org or email@example.com.
(Manuscript accepted 13 January 2017).