Accidental intake of tritiated water: a cytogenetic follow-up case on translocation stability and dose reconstruction

Purpose: To examine by fluorescence in situ hybridization (FISH) chromosomal translocations in a person who, 11 years previously, had accidentally incorporated tritiated water. To compare the resultant estimate of radiation dose with contemporary dosimetry made by urine analysis and dicentric chromosome scoring. Materials and methods: Blood lymphocytes were shared by two laboratories each performing the FISH analysis using different chromosome probe combinations. Doses were calculated by reference to an in vitro calibration curve produced in one of the laboratories. Results: Good agreement in translocation yields was found by the two laboratories. Comparing the yields with the dicentric frequency obtained shortly after the accident and with a translocation frequency measured 6 years post exposure showed good agreement between all measurements. This indicates essentially perfect stability for translocations over an 11 year period in this individual. Conclusions: Dose reconstruction based on FISH-measured translocations showed good agreement with the dose estimated from initial dicentric measurements and from measurements of tritium in urine. Because of the extensive initial dosimetry performed on this individual, who received a uniform whole-body irradiation, the case serves as an excellent test for the use of FISHmeasured translocations for retrospective biodosimetry.