Report from the techa river dosimetry review workshop held on 8-10 December 2003 at The State Research Centre Institute of Biophysics, Moscow, Russia.

Large releases of fission products into the Techa River, in the Southern Urals, occurred in 1950 and 1951, during the early years of operation of the Mayak Production Association (Mayak PA), which produced plutonium for nuclear weapons. Increases of leukemia and of solid cancers with radiation dose have been noted in the population of about 30,000 people who lived in the settlements downstream of the site of the radioactive releases; that population has been studied for several decades by Russian scientists, notably in the framework of cooperation with American and European scientists. The radiation doses are currently estimated by means of the Techa River Dosimetry System-2000 (TRDS-2000). Recently, a scientist from Mayak PA has suggested in several publications that the doses calculated using TRDS-2000 might be underestimated substantially. A special international Workshop, held in Moscow on 8-10 December 2003, aimed to resolve some of the pressing issues related to the determination of the external and internal doses received by the Techa River population and to give recommendations on the further development of methodologies used for dose reconstruction. The authors of this article were selected by the organizers of the Workshop to draw the conclusions of the meeting. They express the view that, while the dose reconstruction system TRDS-2000 is basically sound, additional work is needed and the results of any epidemiological studies making use of TRDS-2000 should be qualified as preliminary, pending resolution of several issues. The most important of these issues is the re-evaluation of the activities released, using additional information that could be obtained with the help of Mayak experts. Other specific suggestions aiming to improve the dose reconstruction methodology for the Techa River cohort, i.e., continued measurements of accumulated dose in environmental samples and human tissues, validation of external dose estimates with thermoluminescence measurements of bricks and with electron paramagnetic resonance measurements of teeth, estimation of individual doses instead of group doses, detailed account of the contributions to dose of medical examinations and of other releases from the Mayak complex, and careful assessment of the uncertainties, were made by the meeting participants.