FISH analysis of translocations induced by chronic exposure to Sr radioisotopes: second set of analysis of the Techa River Cohort

Fluorescent in situ hybridisation analysis of stable translocations was performed for 26 residents living along the Techa River (Russia), who were predominantly (95 %) exposed to ingested strontium radioisotopes (Sr-89 and Sr-90) resulting in exposure of their red bone marrow (RBM). Analysis was conducted at the Urals Research Center for Radiation Medicine, Public Health England and Leiden University Medical Center. Each laboratory scored 1000 cells per donor, which resulted in similar to 1000 genome equivalents (GE) per donor. The age-dependent spontaneous level of translocations for each donor was evaluated on the basis of data published by Sigurdson et al. (International study of factors affecting human chromosome. Mutat. Res. 2008;652:112-121). Reconstruction of doses was performed with the 'Techa River Dosimetry System' developed in 2009. In the studied donors, the range of individual cumulated RBM dose was from 0.3 to 3.7 Gy. Analysis of the yield of stable translocations dependent on the individual RBM dose from Sr-89,Sr-90 showed a linear dose-response relationship of 0.007 +/- 0.002 translocation/GE cell/Gy (R = 0.61, p = 0.001). This set of results was in a good agreement with the previous data reported for 18 donors by Vozilova et al. (Preliminary FISH-based assessment of external dose for residents exposed on the Techa River. Radiat. Res. 2012;177:84-91).