Kaspar Kööp, PhD, Nuclear Safety Specialist
Article from shortened version appeared 9.12.2020 in ERR Novaator.
Introduction: nature, course, causes and risk factors of leukaemia: https://sinutervelaps.blog/2018/05/24/lapseea-koige-sagedasem-vahk-voib-olla-ennetatav/
Doctoral student, Institute of Ecology and Earth Sciences, University of Tartu Ants Tull presented his in an opinion article on serious allegations that the construction of a nuclear power plant poses a risk of leukaemia, especially in children and the foetus. This is a very important issue that needs to be thoroughly discussed when considering the development of a small reactor in Estonia.
The link between childhood leukaemia and nuclear power plants has been studied for decades (UNSCEAR 2017). It is a well-studied area (Boulton 2019), which is confirmed by the fact that a large number of different studies and methods have failed to find such a link, as pointed out by Krämer and Armingen in their analysis (Krämer and Arminger 2010).
- "No excessive cases were found in small towns around the station (Sofer et al. 1991)."
- "Our study does not provide evidence of an increased risk of childhood leukaemia in the vicinity of nuclear facilities (Michaelis et al. 1992)".
- "No increase in leukaemia and lymphoma mortality in the vicinity of nuclear power plants in Japan (Iwasaki et al. 1995)."
- "We did not observe statistically significant clustering in the cases studied at the four nuclear plants (Waller et al. 1995)."
- "There was no evidence of an overall increased risk of childhood leukaemia [...] in the vicinity of nuclear facilities in Scotland (Sharp et al. 1996)".
- "No increase in the risk of hematological malignancies in children in the whole zone (Bouges et al. 1999)."
- "Our study does not show any evidence of an increased risk of childhood leukaemia within 20 km of the 29 nuclear sites studied (White-Koning et al. 2004)".
- "There is no indication of any effect on the incidence of childhood cancer (COMARE 2006)."
- "It is concluded that there is no evidence that acute leukaemia in children under five years of age is more common in the vicinity of nuclear power plants in the UK (Bithell et al. 2008)."
- "No statistically significant mean was observed either for the whole study area or near individual nuclear power plants (Kaatsch et al. 2008)."
- "Our results do not suggest an increase in childhood leukaemia and other cancers in the vicinity of Finnish nuclear power plants (Heinävara et al. 2009)".
Why is it that different studies come to similar conclusions (leukaemia incidence seems to be higher than average near nuclear power plants), but do not support a causal link? I will highlight a few points from Krämer and Arminger's analysis (Krämer, Arminger 2010):
- One of the factors that allows for different correlations is the period of the survey. There are several examples of studies where higher mortality was found only in certain periods but not in others (Kaatsch et al. 2008, Heasman et al. 1987). Studies on the high number of cases of childhood leukaemia in Canada in the vicinity of nuclear power plants, which Greiser uses in his findings (Greiser 2009), only cover the period up to 1986. After that year, the number of cases did not exceed a statistically significant level.
- The choice of the distance from a potential radiation source may also affect the results of the survey in a more heterogeneous direction. Different studies use different distances, such as 6.5 km (Evrard et al. 2006), 20 km (Laurier et al. 2008), 25 km or 50 km (COMARE 2005, 2006), or the entire national territory, as in most Canadian and US studies. Due to the large number of studies, it is easy to find distances with higher mortality than other distances. However, there is no evidence that the probability always increases with decreasing distance. Laurier (Laurier et al. 2006) found that fewer cases of leukaemia were observed at 5 km than expected; whereas at 20 km, more cases were found than expected. Similar results were obtained by Bithell (Bithell et al. 2008), who found "no association between childhood leukaemia cases and the proximity of nuclear power plants in the UK".
- There is also no consistency in the types of cancer. Among the diseases studied were myeloid leukaemia, acute lymphoblastic leukaemia, acute non-lymphoblastic leukaemia, non-Hodgkin's lymphoma, as well as other cancers. The multiplicity of disease types means that certain types of cancer may be more prevalent in one location, while others are less prevalent in others. Kaatsch (Kaatsch et al. 2008) et al. found a multiplicity of cases of leukaemia, while other childhood cancers were fewer in the vicinity of nuclear power plants. Such a correlation is difficult to explain if the aim of the study was to prove that living close to nuclear power plants causes leukaemia.
The multiplicity of variables across studies also provides the opportunity to find very different and sometimes recurrent correlations that appear statistically significant at first glance and without in-depth investigation, but which have not been shown to be statistically significant by replicate studies. When conducting a study with many variables, it is easy to find a situation that corresponds to the original hypothesis, as in the case of Körblein and Hoffmann (Körblein and Hoffmann 1999), cited by Mr. Tull, who, after an initial negative study result, achieved their goal by using the same original data but changing the methodology of the analysis. In the Körblein and Hoffmann studies, as in the later control studies, only the home address at the time of diagnosis was taken into account. It is not known how long the person had lived at this address before. Nor is it known how much of the child's daily life was spent at this address. It was not investigated where the child attended kindergarten, whether and how much time was spent with grandparents, on holiday trips (the radiation dose from air travel is several times higher than from living near a nuclear power plant), camps, etc.. However, such data would be needed to estimate radiation doses, as one hypothesis was the effects of radiation specifically from nuclear power plants, but in practice the time spent near a nuclear power plant was not estimated. The study also does not take into account the magnitude of the local background radiation, which can vary considerably between different regions of Germany. In summary, the most important shortcoming of the study is that it examined only one aspect, namely distance from the plant, while it is known that leukaemia can be caused by many factors that were not investigated.
Tull's article also states that "children still in the womb are highly susceptible to radiation, as stem cells in the bone marrow and lymphoid tissues are highly sensitive to radioactivity, which induces mutations in white blood cells". However, reference is made to studies of genetic radiation damage to women who survived the atomic bombings of World War II in Japan and their unborn children at the time. Indeed, the results of this study have been misinterpreted in the past and the results suggest the opposite (COMARE 2016). Instead, Ohtaki et al (Ohtaki et al. 2004) found that women who were irradiated by an atomic bomb explosion in utero children whose radiation dose exceeded ~100 mGy were less likely to exhibit stable chromosome translocation, unlike their mothers who did - suggesting that cells in the mother's womb were better able than adult cells to repair DNA damage.
Such inconsistencies will undoubtedly attract the attention of other researchers, which is why it is always worth paying attention not only to the studies themselves, but also to the feedback they have received from the scientific community (COMARE 2016, UNSCEAR 2017).
Since Ants Tull's article focused on leukaemia research in Germany, it is also worth mentioning the overall figures for leukaemia in Germany in general. The basic data from the studies cited show that around 1 800 children under the age of 15 develop a malignant disease (cancer) in Germany every year (Kaatsch et al. 2008). In 600 cases, the form of cancer is leukaemia, with a median age of 5 years. Leukaemia is the most common form of cancer in children under 5 years of age, with 5 cases per 100 000 children in Germany. Both in Germany and in the rest of Europe, the incidence of leukaemia in children has risen by an average of 0.6% per year between 1978 and 1997 (Kaatsch et al. 2006), with the risk being higher in industrialised countries. Regional short-term cholelithiasis occurs in rural areas and is thought to be caused by some infectious pathogen. For example, (Alexander et al. 1998) found that subjects in a study had a higher than statistically expected time-space overlap, i.e. people stayed in the same place at the same time more than expected. This suggests that there is a statistical relationship between human exposure and leukaemia clusters.
Although scientists generally acknowledge that high doses of ionising radiation can cause leukaemia, it has not been proven that low doses do either (CNCS 2020). Nonetheless, modern radiation protection is built on the conservative assumption that even low doses of radiation can increase the development of cancer. Today's radiation protection allows only those practices that result in an annual dose to the general population below 1 mSv. This requirement also applies to nuclear power plants, but in normal practice doses are well below the limit. By way of comparison, the average dose from various natural radiation sources in Estonia is around 3 mSv/year (Lust 2012).
Data on radiation from German nuclear power plants do not indicate that, on the basis of current knowledge, it would have been possible to receive a dose high enough to cause leukaemia on the basis of current research. Based on the known data, the radiation from each of the plants under investigation was well over 1,000 times lower than the annual natural and medical dose to humans (COMARE 2011).
The Baker article cited by Tull summarizes his meta-analysis well, writing, "If doses are too low to increase the risk of morbidity, one would expect morbidity levels to remain the same before and after the start-up of the plant.". A number of studies were able to estimate morbidity in areas before and after nuclear plant start-up (Baron 1984; Clarke et al. 1989, 1991; Jablon et al. 1990; McLaughlin et al. 1993). The level of morbidity remained unchanged even in areas where it was already higher. For example, Jablon studied 62 nuclear plant sites in the USA and found that the incidence of leukaemia in children was higher even before the plant was operational (Jablon et al. 1990)'.
One more interesting correlation. In 1989, a study was published which came to a rather intriguing conclusion. It analysed human health data and the risk of mortality from leukaemia in 400 different areas of England and Wales where nuclear power stations were located, or where they had been considered but never built. It was found that young people's mortality rates from leukaemia and Hodgkin's disease were comparable near nuclear power stations that were built or not built. The implication of this study is that the risk of leukaemia may be increased not by the nuclear power plant but by other, unidentified risk factors (Cook-Mozaffari 1989).
So cancers, including leukaemia, can be caused by a wide range of factors that affect people.
Geraldine Thomas, Professor of Molecular Pathology at Imperial College, says the best scientists around the world have failed to confirm a causal link between low radiation doses and health effects. It could be likened to looking for a needle in the haystack of environmental toxins we all live in. However, only a fraction of this is ionising radiation, of which 85% is estimated to be of natural origin and not a direct consequence of human activity (Thomas 2016).
In conclusion, based on extensive research and observational studies, there is no proven link between living near a nuclear power plant and cancer.
I also think it is of the utmost importance to explain why we at Fermi Energy are dealing with such a complex issue as Estonia's own nuclear power plant in the first place. The reason is simple - we do not know of any other alternative to ensure large-scale, long-term, carbon-free power generation without higher costs for Estonian electricity consumers. The only way to generate electricity in Estonia without weather dependence is either to burn something or to use nuclear power. We are not in favour of incineration, because it is precisely the burning of different materials - fossil fuels or wood - that releases huge quantities of atmospheric pollutants that are very directly and demonstrably harmful to human health. It is estimated that 8.8 million people die prematurely each year from the emissions of burning coal and other fossil fuels for electricity (Lelieveld et al. 2019). This figure is no longer a random correlation, but is proven by repeated and annual studies.
Our argument at the meeting in Kunda, without having seen the content of the studies presented by Ants Tull on board, was that if there were indeed unequivocal scientific evidence of infant leukaemia from the use of nuclear power, is it credible that in a democratic and free press in Finland, Sweden, the rest of the European Union, the United States, Canada, Korea, Japan, and many other countries, such power plants would not be closed down overnight by national nuclear regulators? We, at Fermi Energia, assure you with full responsibility to ourselves, our family, the Estonian public and all residents that we will only consider technologies that ensure the highest level of safety and significantly reduce the environmental footprint compared to today's energy production. In the coming years, we will prove our technical choices to international partners and regulatory authorities, to competent officials and scientists, and to the Estonian public.
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