Hypothesis to explain child leukemias near NPPs – Rebuttal rebutted

Dr Ian Fairlie, September 30, 2026, https://www.ianfairlie.org/news/hypothesis-to-explain-child-leukemias-near-npps-rebuttal-rebutted/

Official Rebuttal of Tritium Hypothesis

It has recently come to my attention that in 2016 a rebuttal was published in an official report of my hypothesis to explain increased incidences of cancers among children residing near nuclear power plants (NPPs). The rebuttal is contained UNSCEAR (2016) Annex C: Biological Effect of Selected Internal Emitters -Tritium. Although this rebuttal was published 10 years ago, it’s the only official response to my hypothesis so it’s worth examining the matter. I shall show here that the UNSCEAR riposte has several shortcomings which render its argument unreliable. The main conclusion is that the absence of increased leukemias could be due to several naturally-occurring processes factors and does not necessarily invalidate the NPP hypothesis.

Exposures near NPPs

The estimation of radiation exposures from NPP emissions has rarely been examined in the scientific literature. One exception is Hill (1986). The difficulty is that such estimations are complex. Briefly, they require several computer models to estimate nuclide emission rates, the transport of radionuclides through the environment to man, human uptake and retention Bq models. Lastly, they require estimated dose coefficients to convert Bq to Sv. Further complexities occur with chronic rather than single exposures, and with organic binding in the case of tritium releases. The above models all require several assumptions to be made which may or may not have been validated by environmental or clinical data. Uncertainties abound in each model, which need to be multiplied and/or added together. The main conclusion of the UK Government’s CERRIE report (Cerrie, 2004) was that the resulting uncertainties could be very large.

The upshot is that official dose estimates from NPP emissions are not necessarily reliable and could be significant underestimates.

In 2010, Fairlie (2010) first published a hypothesis to explain the observed increases in childhood leukemia near NPPs. This suggested that large releases of tritium from NPPs during ~annual refuelling episodes (when reactors were depressurised) resulted in tritium plumes downwind from NPPs. Pregnant women living within ~5 km of these locations could have inhaled high concentrations of tritiated water vapour. It was further suggested that the haematopoietic tissues (including nascent bone marrow) in the developing fetuses/embryos were labelled with this tritium. These tissues are highly radiosensitive. This resulted in babies being born with pre-leukemic cells which, after birth, developed into full-blown leukemias. The product of large increases in estimated radiation dose times the estimated large increase in radiation risk explained the discrepancy between official estimates and the actual cancer increases.

This hypothesis was more fully developed and explained by the author in a longer published article (Fairlie, 2014) not cited by UNSCEAR. Many studies since then have indicated increased incidences of childhood cancers, including leukemias, among children near NPPs (Fairlie, 2024).

REBUTTAL

It appears that no dissenting or corrective articles on this hypothesis were published in peer-reviewed scientific journals in 2010, 2014 or in subsequent years. However in 2016 an UNSCEAR report was published with a scientific addendum (Annex C) on tritium (UNSCEAR, 2016). This contained a rebuttal of the author’s hypothesis. In brief, the UNSCEAR Annex stated that, if the NPP hypothesis were correct, then the large releases of tritium from the atmospheric bomb tests in the 1950s and 1960s (see Figure 3.1) should have resulted in increases in leukemia deaths world-wide which were not observed (Wakeford et al, 2010). Therefore, in the view of the authors of the UNSCEAR 2016 Annex C report, the NPP hypothesis was not supported.

However the UNSCEAR explanation has several shortcomings which render its argument unreliable. One of the most obvious shortcomings is that the UNSCEAR scheme conflicts with the scientific axiom “absence of evidence is not evidence of absence” (Sagan and Druyan (1995); Altman and Bland, 1995). In other words, the mere fact that we lack evidence here for the NPP hypothesis does not warrant us to infer that the hypothesis is false.

But even if we look at the UNSCEAR argument in more detail, it does not withstand much scrutiny. The Annex C authors argue that an examination of childhood leukaemia incidence in cancer registries in three continents found no evidence of a wave of excess cases corresponding to the peak of radioactive fallout from atmospheric weapons testing (Wakeford et al, 2010). The authors then state that the absence of a “discernible” leukaemia increase following the main peak of testing (1962-63) is evidence against the NPP hypothesis. Let us examine the UNSCEAR argument in more detail.

Bomb Tests

The UNSCEAR argument juxtaposes tritium exposures from NPPs and the peak period (1961-1962) of the bomb tests – but these are substantially different in nature, size, and duration. Most important for health outcomes, their resulting tritium concentrations are likely to have been quite different. To wit, bomb test tritium was ejected high into the Earth’s troposphere and stratosphere and was thus distributed world-wide – mostly in the northern hemisphere, mainly in 1961-1962. See Fig 3.1 below, from IAEA (2025).

Bomb Tests

The first is via atmospheric mixing. According to Jenkins (2001) “the detonations generally injected the tritium into the stratosphere, where it was quickly oxidized to form water vapour. Over a period of a few years, the tritiated water vapour was transferred to the troposphere, where it was rapidly ‘rained out’ to the earth’s surface. The delivery of bomb tritium to the earth’s surface was monitored by a number of World Meteorological Organization /International Atomic Energy Authority precipitation sampling stations. The pattern and timing of this delivery have been shown to consist of two primary components: a dominant northern, spike-like component, and a weaker southern component.”

The second natural process occurs by isotopic exchange between ³H and ¹H. At the molecular level, atomic exchange between the two H isotopes is near instantaneous. The main point here is that the quantity of naturally-occurring hydrogen (¹H) in the form of water (H₂O) on Earth is very large. About 61% of the northern hemisphere is covered by oceans and seas and a further ~1% by Greenland’s ice sheet. During winter, seasonal snow and ice-covered land (including arctic tundra and boreal regions) across the northern hemisphere expand to cover about 16% to 18% of the surface area of the northern hemisphere. Therefore ~80% of the northern hemisphere is covered by forms of water – at least during winter.

Due to atmospheric mixing and isotopic exchange between ³H and the very large volumes of ¹H in the oceans, seas, lakes, ice sheets, and Arctic tundra and boreal regions in the northern hemisphere, atmospheric concentrations of HTO vapour will have been reduced. This would have occurred relatively quickly.

Indeed, direct evidence of the relatively quick incorporation of atmospheric tritium into surface waters is given in figure 1 of the UNSCEAR Annex itself. This shows environmental tritium levels in surface water in the United States in 1951–1975 and is reproduced below.

This figure [on original] shows that atmospheric tritium is quickly taken up by surface waters, as their tritium concentrations mainly follow the temporal pattern of the tests shown in figure 3.1.

It is important to note that it’s tritium in atmospheric water vapour and not tritium in drinking water that would have been the main problem health-wise. This is for two reasons. First, the main uptake routes would have been via inhalation and skin absorption; and second, the main tritium sink would have been water in seas and oceans …which is not consumed as drinking water.

Source: Bennett (1973)

Another mechanism – escape of H from the stratosphere

A third natural mechanism is that some molecular³H, being much lighter than air, will have escaped from the Earth’s atmosphere in the form of hydrogen gas, shortly after the explosions.

It is not possible at this point to estimate the magnitudes of the reductions in tritium’s air concentrations due to these three natural processes. But they could be significant – leading to a paucity of observations of increased health effects.

The main conclusion is that the absence of increased leukemias could be due to several factors and does not necessarily invalidate the NPP hypothesis.

(Postscript: The above discussion of dilution mechanisms is not intended to defend tritium releases from the bomb tests. On the contrary, it shows that the atmospheric bomb tests in the 1950s and 1960s radioactively contaminated the totality of the northern hemisphere’s oceans, seas, lakes, ice sheets, and snow-covered lands with low levels of tritium. In the author’s view, this legacy of the bomb tests is regrettable and should not be repeated.)

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Appendix: comparison of estimated tritium concentrations…………………………………………………………………….