Added predictive ability of the information on job strain beyond the standard Framingham risk score.

16.35 expected cases) published by the Committee on Medical Aspects of Radiation in the Environment (COMARE) differ from those used by Körblein. Of note, COMARE reported a combined SIR of 1.07 (95% CI 0.92–1.26) from a random-effects metaanalysis of 37 estimates from five countries. Körblein rightly points out that the 95% CI of the rate ratio estimate from the main analysis of childhood leukaemia in 0to 4-year olds just includes the point estimate (2.19) of the German KiKK study. However, there is in fact considerable disagreement between the two studies. Assuming that the true IRR for leukaemia in 0to 4-year olds comparing the 0to 5-km zone with the 415-km zone around NPPs is indeed 2.2 (as estimated in the KIKK study), the probability of observing an IRR of 1.2 (as in our study) is 0.03 (Figure 1) and the power of rejecting the null hypothesis of no association at the 5% significance level is 76%. Chirga argues that estimates of mean annual radiation doses originating from nuclear power plants (NPPs) are uncertain and that actual doses might fluctuate over time. He suggests that short spikes in emissions could increase the incidence of childhood cancer. Whereas we cannot exclude this possibility, we reiterate that our study provides little evidence that the rate of childhood cancer is higher in the proximity of NPPs. The few cases of cancer occurring in excess of the expected number of cases among children living in the 5-km zone around Swiss NPPs are well within statistical uncertainty, and so is the deficit of cases a few kilometres further afield. We agree with Chirga that our main exposure measure, Euclidean distance of place of residence to nearest NPP, was crude and can only serve as a proxy for true radiation exposure.