Childhood leukemia, atmospheric test fallout and high voltage power distribution lines

An association between increased rates of childhood leukemia and proximity to high voltage electricity power transmission lines was found in a 2005 study by Draper et al. More recently, this study was extended to include a further period of time and with an enlarged dataset by Bunch et al 2014, the result being that there was no longer any overall statistically significant effect for the whole period. Using the data from these two studies the trend in Relative Risk with fallout dose is examined for five sub-periods 1962-69, 1970-79, 1980-89, 1990-99 and 2000-2008. The effect turns out to be significantly associated with the levels of radioactive fallout from atmospheric testing (Chi-square for trend = 7.6; p = 0.006). A non-linear association between the Relative Risk and the Fallout doses is robust, R2 = 0.955; F-statistic 65.6; p = 0.004. Fews et al. (1999) raised the issue of the concentration of airborne radioactive particles near power lines and it is suggested that the observed trend in Relative Risk with time supports a hypothesis in which the inhalation of radioactive particulates from fallout may be the cause, or related to the cause of the effect. The hypothesis is extended to a general discussion of child leukemia and radiation which implicates particulates. Correspondence to: Christopher Busby, Environmental Research SIA, 1117 Latvian Academy of Sciences, Riga LV-1050, Latvia, E-mail: christo@ greenaudit.org Received: September 25, 2017; Accepted: October 18, 2017; Published: October 20, 2017 Introduction The issue of child cancer and high voltage power lines has been an area of controversy since 1979 when Wertheimer and Leeper reported an association with low frequency (wiring) electromagnetic (EM) radiation [1]. A 2005 large case-control study by the Childhood Cancer Research Group (CCRG) in Oxford [2] demonstrated a modest but statistically significant excess of child leukaemia 0-14 in those living less than 600m from a high voltage power line. For those children within 200m the relative risk (RR) was 1.64. This Draper et al study [2] covered the period 1962-95 and involved 9700 children with leukemia and the same number of controls. The powerlines examined were the 400 and 275kV lines. An extension of this large case control study by Bunch et al, was published in the British Journal of Cancer on 6th February 2014 [3]. The Bunch et al 2014 study [3] increased the number of children with leukaemia to 16620 by extending the period from 1962 to 2008 and adding Scotland to England and Wales. The authors found that over the whole period and for all the children the effect declined over time from a relative risk of 4.5 in the 60s to 0.71 in the 2000s. They conclude that “a risk declining over time” cannot arise from any physical effect of the powerlines and is more likely to be a result of changing populations of those living near powerlines. However, there is a potential explanation. Since childhood leukemia has been associated in many studies [4-10] with proximity to nuclear sites, in particular fuel reprocessing sites like Sellafield in the UK [10] it seems possible that radioactive exposures of some kind may be reasonably investigated as a cause. The largest injection of radioactivity into the global environment was the atmospheric nuclear testing that was carried out in the period 1950-1963 when the fallout contamination peaked in 1959-63. However, studies using data after 1960 have not reported any significant large excess risk of child leukemia trends [11,12]. This may be because the same period of high fallout exposures saw an increase in infant mortality from all causes, an effect which is capable of quenching increases of child leukemia at higher doses due to the death of pre-leukemic individuals due to immune system incompetence [13]. On the other hand, within national data, child leukemia at the time of the peaks in weapons fallout has been associated with fallout exposure using rainfall as a surrogate. [14]. Since it has been established that high voltage power lines concentrate particles [15] it was of interest to see if the variation in the power line and child leukemia association could be explained by the trend in fallout over the period of the power line studies. Clearly, although all individuals were exposed to fallout over the period of testing, these case control studies [2, 3] are comparing leukemia rates in children and their parents exposed to fallout particles concentrated by the electrostatic effects of power lines with those not so exposed. Data, method and results The data for the examination of the trend in child leukemia effect is available from the two studies of the Childhood Cancer Research Group (CCRG), in 2005 [2] and 2014 [3]. The data from the Bunch et al 2014 study [3] enables a straightforward analysis of any effect. The data, cases and controls were grouped into 5 periods, 1962-1969, 1970-1979, 1980-1989, 1990-2000 and 2000-2008. The numbers are given in table 1 together with the Relative Risks reported by Bunch et al 2014. The association between the trend in childhood leukemia and the trend in radioactive fallout was examined. Data for fallout is available from the UK annual reports of the Letcombe Research laboratory, from measurements made by the Atomic Energy Research Establishment Harwell and from the 2000 and earlier reports of the United Nations [16-18]. In table 2 the mean fallout doses (as calculated by the UK National Radiological Protection Busby C (2017) Childhood leukemia, atmospheric test fallout and high voltage power distribution lines Volume 2(4): 2-4 Pediatr Dimensions, 2017 doi: 10.15761/PD.1000154 Board [19]) are given together with the Relative Risks obtained for the same period by the Bunch et al 2014 study. The association between mean fallout dose and Relative risk was tested using the extended Mantel Haenszel χ2 for trend. Result showed a highly significant association χ2 = 7.62; p = 0.006. The trend in between childhood leukemia risk and fallout doses is shown in figure 1. The dose response relationship seen in the association is shown in figure 2. It is concave downwards or hogs-back.