Leukaemia incidence among Chernobyl accident emergency workers over the follow up period from 1986 to 2007

Dynamics of the leukaemia incidence in the cohort of 104 thousand Russian emergency accident workers (EAWs), men, over the period from 1986-2007 was examined. The average age of the EAWs at the time of their arrival at the working area was 34 years. Maximal SIR values for leukaemia in the cohort was over the 10-year period, 1990-1999, SIR values close to the unity were observed over the initial (1986-1989) and in the finite (2000-2007) periods. Radiation risk of leukaemia (excluding ChLL) was estimated for 75 thousand EAWs of the cohort with official individual external gamma-radiation doses to a whole body, accumulated over the working period. Mean radiation dose was 108 mGy, the highest dose was 500 mGy. Statistically significant (p=0.05) linear relationship between dose and leukaemia incidence was in the period (1989-1997), ERR/Gy=4.76. Over the period from 1998 to 2007 the radiation risk of leukaemia was not found. Obtained results allow us to conclude that excess leukaemia incidence possibly caused by external gamma-radiation is observed in 3-11 years after the exposure.