I disagree with your view that the risks of chronic exposure to ‘low level’ radioactivity in Kazakhstan should inform debate on expanding nuclear power to reduce carbon emissions (Nature 568, 22–24; 2019). I find it alarmist and misleading.

It is alarmist because the detonation of nuclear weapons at the Semipalatinsk test site exposed the public to much higher doses of radiation than even the most catastrophic accidents at nuclear reactors such as Chernobyl and Fukushima. It is misleading because, despite extensive research, no adverse effects of chronic exposure to low-level radiation (less than 500 millisieverts per year) have been detected (M. Tubiana et al. Radiology 251, 13–22; 2009). Safety levels are set far below this by regulators out of caution, not because there is any evidence of harm.

The risks of nuclear energy need to be compared with the higher risks of alternative energy sources, notably fossil fuels. By replacing some generators fired by fossil fuels, nuclear energy has saved an estimated 2 million lives since 1971 (see P. A. Kharecha and J. E. Hansen Environ. Sci. Technol. 47, 4889–4895; 2013). Moreover, avoiding the risk of severe climate change requires a rapid reduction in greenhouse-gas emissions, which is not achievable without the expansion of nuclear power.