In March 2014, my article on increased rates of childhood leukemias near nuclear power plants (NPPs) was published in the Journal of Environmental Radioactivity (JENR). A previous post discussed the making of the article and its high readership: this post describes its content in layman’s terms.

Before we start, some background is necessary to grasp the new report’s significance. Many readers may be unaware that increased childhood leukemias near NPPs have been a contentious issue for several decades. For example, it was a huge issue in the UK in the 1980s and early 1990s leading to several TV programmes, Government Commissions, Government committees, a major international Conference, Government reports, at least two mammoth court cases and probably over a hundred scientific articles. It was refuelled in 1990 by the publication of the famous Gardner report (Gardner et al, 1990) which found a very large increase (7 fold) in child leukemias near the infamous Sellafield nuclear facility in Cumbria.

The issue seems to have subsided in the UK, but it is still hotly debated in most other European countries, especially Germany.

The core issue is that, world-wide, over 60 epidemiological studies have examined cancer incidences in children near nuclear power plants (NPPs): most (>70%) indicate leukemia increases. I can think of no other area of toxicology (eg asbestos, lead, smoking) with so many studies, and with such clear associations as those between NPPs and child leukemias. Yet many nuclear Governments and the nuclear industry refute these findings and continue to resist their implications. It’s similar to the situations with cigarette smoking in the 1960s and with man-made global warming nowadays.

In early 2009, the debate was partly rekindled by the renowned KiKK study (Kaatsch et al, 2008) commissioned by the German Government which found a 60% increase in total cancers and 120% increase in leukemias among children under 5 yrs old living within 5 km of all German NPPs. As a result of these surprising findings, governments in France, Switzerland and the UK hurriedly set up studies near their own NPPs. All found leukemia increases but because their numbers were small the increases lacked “statistical significance”. That is, you couldn’t be 95% sure the findings weren’t chance ones.

This does not mean there were no increases, and indeed if less strict statistical tests had been applied, the results would have been “statistically significant”. But most people are easily bamboozled by statistics including scientists who should know better, and the strict 95% level tests were eagerly grasped by the governments wishing to avoid unwelcome findings. Indeed, many tests nowadays in this area use a 90% level.

In such situations, what you need to do is combine datasets in a meta-study to get larger numbers and thus reach higher levels of statistical significance. The four governments refrained from doing this because they knew what the answer would be, viz, statistically significant increases near almost all NPPs in the 4 countries. So Korblein and Fairlie helped them out by doing it for them (Korblein and Fairlie, 2012), and sure enough there were statistically significant increases near all the NPPs. Here are their findings-

Studies of observed (O) and expected (E) leukemia cases within 5 km of NPPs

O E SIR=O/E 90% CI p-value Germany 34 24.1 1.41 1.04-1.88 0.0328 Great Britain 20 15.4 1.30 0.86-1.89 0.1464 Switzerland 11 7.9a 1.40 0.78-2.31 0.1711 Franceb 14 10.2 1.37 0.83-2.15 0.1506 Pooled data 79 57.5 1.37 1.13–1.66 0.0042

a derived from data in Spycher et al. (2011).

b acute leukemia cases

This table reveals a highly statistically significant 37% increase in childhood leukemias within 5 km of almost all NPPs in the UK, Germany, France and Switzerland. It’s perhaps not surprising that the latter 3 countries have announced nuclear phaseouts and withdrawals. It is only the UK government that remains in denial.

So the matter is now beyond question, ie there’s a very clear association between increased child leukemias and proximity to NPPs. The remaining question is its cause(s).

Most people worry about radioactive emissions and direct radiation from the NPPs, however any theory involving radiation has a major difficulty to overcome, and that is how to account for the large (~10,000 fold) discrepancy between official dose estimates from NPP emissions and the clearly-observed increased risks.

My explanation does involve radiation. It stems from KiKK’s prinicipal finding that the increased incidences of infant and child leukemias were closely associated with proximity to the NPP chimneys. It also stems from KiKK’s observation that the increased solid cancers were mostly “embryonal”, ie babies were born either with solid cancers or with pre-cancerous tissues which, after birth, developed into full-blown tumours: this actually happens with leukemia as well.

My explanation has five main elements. First, the cancer increases may be due to radiation exposures from NPP emissions to air. Second, large annual spikes in NPP emissions may result in increased dose rates to populations within 5 km of NPPs. Third, the observed cancers may arise in utero in pregnant women. Fourth, both the doses and their risks to embryos and to fetuses may be greater than current estimates. And fifth, pre-natal blood-forming cells in bone marrow may be unusually radiosensitive. Together these five factors offer a possible explanation for the discrepancy between estimated radiation doses from NPP releases and the risks observed by the KIKK study. These factors are discussed in considerable detail in the full article.

My article in fact shows that the current discrepancy can be explained. The leukemia increases observed by KiKK and by many other studies may arise in utero as a result of embryonal/fetal exposures to incorporated radionuclides from NPP radioactive emissions. Very large emission spikes from NPPs might produce a pre-leukemic clone, and after birth a second radiation hit might transform a few of these clones into full-blown leukemia cells. The affected babies are born pre-leukemic (which is invisible) and the full leukemias are only diagnosed within the first few years after birth.

To date, no letters to the editor have been received pointing out errors or omissions in this article.

REFERENCES

Bithell JF, M F G Murphy, C A Stiller, E Toumpakari, T Vincent and R Wakeford. (2013) Leukaemia in young children in the vicinity of British nuclear power plants: a case–control study. Br J Cancer. advance online publication, September 12, 2013; doi:10.1038/bjc.2013.560.

Bunch KJ, T J Vincent1, R J Black, M S Pearce, R J Q McNally, P A McKinney, L Parker, A W Craft and M F G Murphy (2014) Updated investigations of cancer excesses in individuals born or resident in the vicinity of Sellafield and Dounreay. British Journal of Cancer (2014), 1–10 | doi: 10.1038/bjc.2014.357

Fairlie I (2013) A hypothesis to explain childhood cancers near nuclear power plants. Journal of Environmental Radioactivity 133 (2014) 10e17

Gardner MJ, Snee MP; Hall AJ; Powell CA; Downes S; Terrell JD (1990) Results of case-control study of leukaemia and lymphoma among young people near Sellafield nuclear plant in West Cumbria. BMJ. 1990;300:423–429.

Kaatsch P, Spix C, Schulze-Rath R, Schmiedel S, Blettner M. (2008) Leukaemia in young children living in the vicinity of German nuclear power plants. Int J Cancer; 122: 721-726.

Körblein A and Fairlie I (2012) French Geocap study confirms increased leukemia risks in young children near nuclear power plants. Int J Cancer 131: 2970–2971.

Spycher BD, Feller M, Zwahlen M, Röösli M, von der Weid NX, Hengartner H, Egger M, Kuehni CE. Childhood cancer and nuclear power plants in Switzerland: A census based cohort study. International Journal of Epidemiology (2011) doi:10.1093/ije/DYR115. http://ije.oxfordjournals.org/content/early/2011/07/11/ije.dyr115.full.pdf+html