Busby argues that we drew false conclusions from our study1 by ignoring a possible “Chernobyl effect”, and goes on to draw his own conclusions from the data presented in the paper. We do not accept that our research was flawed, and point out serious shortcomings in Busby’s subsequent analysis and interpretation of the data.

In designing our study, we decided to consider the period 1975–89 as a whole. We were aware that it was possible that excess incidence of childhood leukaemia could have resulted from exposure to radioactive material from the Chernobyl incident, but regarded the likely magnitude of any such effect to be very small. Taking all ages combined, figures published by the Scottish Cancer Registry2 show a very similar incidence of leukaemia in …