In 2013, I discussed several epidemiological studies providing good evidence of radiogenic risks at very low exposure levels.
A powerful new study has been published in Lancet Haematology  which adds to this evidence. However the study’s findings are more important than the previous studies, for several reasons.
First, it provides “strong evidence”, as stated by the authors, of a “dose-response relationship between cumulative, external, chronic, low-dose, exposures to radiation and leukaemia”.
Second, it finds radiogenic risks of leukemia among nuclear workers to be more than double the risk found in a previous similar study in 2005. The excess relative risk of leukaemia mortality (excluding workers exposed to neutrons) was 4.19 per Gy.