Leukemia and cardiovascular diseases in the Techa river cohort: New interpretation required -

The relatively large discharges of radioactive materials into the Techa River in the Southern Urals occurred between the years 1949 and 1956. The most exposed individuals were residents of villages along the river. On the author’s opinion, certain studies tended to exaggerate the relationship between the radiation exposure and enhanced risks e.g. of cardiovascular diseases or leukemia in the Techa River cohort. The study on the cardiovascular diseases was commented previously. The cohort members must have been generally aware of their dose estimates calculated on the basis of their age and residence history. Individuals with higher dose estimates were probably on average more motivated to undergo medical examinations, being at the same time given on average more attention. Accordingly, a detection probability of chronic disease would be probably higher in people with higher dose estimates. One of the mechanisms explaining for correlations between the low-dose radiation exposure and health risks is apparently a dose-dependent difference in the quality and frequency of medical examinations. The dose-effect relationships after low-dose exposures should be studied in animal experiments with exactly known doses and dose rates, possibly shielded from biases and confounding factors.