Wednesday, 1 May 2019

Chernobyl cancer rates revised upwards

The impacts of the Chernobyl nuclear disaster in 1986 included thyroid cancers in those who were children at the time. The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) produced a report in 2008 which found that, among those exposed who had been under 14 years of age in 1986, there were 5,127 reported cases of thyroid cancer between 1991 and 2005, while, for those who had been under the age of 18 in 1986, there were 6,848 cases. The main exposure route is assumed to be from drinking milk  contaminated with radioactive fallout.


Thyroid cancer can be treated e.g. by surgical removal of the thyroid (with patients then having to take compensatory pills for rest of their lives), but even so, fifteen cases had proved fatal by 2005. More are possible later. Thyroid cancer can occur naturally, but UNCEAR accepted that the observed pattern of dramatically increased thyroid cancer in the initial period 1991-1995 was associated with the accident. The typical minimum latency period for thyroid cancers is around 5 years, so it might be hoped that, sometime after that, cases would gradually tail off, but, worryingly, UNCEAR found no evidence for a decrease in the annual excess incidence of thyroid cancer up to 2005- the end of the observation period for the report. However, for those born after 1986, there was no evidence for an increase in the annual incidence of thyroid cancer. On that basis it might be assumed that new exposures or effects were not occurring, but that the latency period for cancers amongst those exposed in 1986 was extending. That cohort might also be joined by those who were in utero at the time.                                                 


There have been follow up studies and reviews and they have produced some worrying conclusions, outlined in a new UNSCEAR report. It notes that ‘the total number of cases of thyroid cancer registered in the period 1991−2015 in males and females, who were under 18 in 1986 (for the whole of Belarus and Ukraine, and for the four most contaminated oblasts of the Russian Federation), approached 20,000. This number is almost three times higher than the number of thyroid cancer cases registered in the same cohort in the period 1991−2005’.


So it’s going up significantly- with females especially at risk. UNSCEAR says ‘on average, the registered numbers of thyroid cancer for females were about four times higher than for males’. Not all of these cases will have been due to radiation exposure. UNSCEAR says other factors include an increased spontaneous incidence rate with adulthood…and improvement in diagnostic methods’.  So they claim that ‘the fraction of the thyroid cancer cases in the period 2001-2008 attributable to the radiation exposure caused by the accident is assessed to be about 0.6 and 0.25 for the evacuated and non-evacuated children and adolescents, respectively’. Even so, that’s nearly 12,000 cases for those in the zone, 1 in 4 for the rest. Although UNSCEAR note that ‘the uncertainty range of the estimated attributable fraction extends at least from 0.07 to 0.5’. They call for more research.

Full report:

Thyroid cancer was only one the impacts of the radiation release at Chernobyl, and children were not the only victims. As well as the rest of the population, many thousands of clean up workers were also exposed, some to high levels, and, although many have died, death was not the only outcome- for them or the others, there were also illnesses later in life that may not always have been linked back to radiation exposure, including immune system degradation:
However, the likely long-term health impacts of what happened at Chernobyl (and Fukushima) are still debated: It’s a contentious area. But the new UNSCEAR study may dent some of the more complacent/official views, for example see:   

Certainly more research is needed, as UNSCEAR says. Its selection of 0.6 and 0.25 as the radiation-related proportion seems debatable- why so low? Also it’s not clear exactly what is happening to the post-Chernobyl population.  Is the rise in cancers due to new exposures? The half life of Caesium 137 is around 30 years, so the activity level of any that remains in the ecosystem should be about 50% less by now and continually falling – so the cancer rate should be falling too, not increasing. More likely is a delayed onset effect from the initial exposures.

The administration of iodide pills, to block Caesium uptake in the thyroid, would have limited the risk, but evidently did not happen much or in time. So now we await the long term results. Fortunately, 25 years later, most children in the Fukushima area seem to have escaped these problems: iodate pills were distributed – though they have to be taken very promptly, and that may not have always happened in the post-accident chaos there. Tragically, once more, we will have to wait to see- although some increases have already been claimed: 

It will take time to know for certain. Some say that you can worry too much about radiation exposure: we are already exposed to natural background radiation and to X-rays used for medical purposes.  Major nuclear accidents expose some people, usually reactor staff and firefighters, to massive doses of radiation, which can kill outright-  30 or more people died soon after Chernobyl.  However, it’s the longer-term risk of absorbing/ingesting/breathing in radio-nuclides that’s the key worry- including isotopes that don’t exist in nature. Once internalized, and if lodged somewhere in your body, the active particles can continue to irradiate cells intensively for very long periods. That’s not the same as exposure to low level background external radiation, or to short exposures from external sources like X-rays, or even to ‘prompt’ radiation fluxes from reactor accidents (or nuclear explosions), if you are some way away. The extra exposures from nuclear plants, including routine and accidental releases, averaged across the wider public over time, can seem small in some cases, but it does all add up, and we need to minimise total exposures, and certainly any internalisation. Especially since it’s not always averaged out: leaks and accidents at nuclear plants can expose many local people to large extra doses, with, as we have seen, uncertain long term results. It is, arguably, not a risk worth taking.  So, it could be argued that the best protection in future is not iodate pills, masks or evacuation. It’s to avoid the use of these plants- and to go for renewables instead. A small local start:

All technologies have health and safety risks, but those associated with the renewables (large hydro dam failures apart) are generally small and local (e.g. a total so far of around 180 wind turbine-related occupational fatalities, mostly from installation accidents) compared with those of nuclear and (especially) the burning of fossil fuels due to air pollution and climate change. Whatever we do now, there will be long-terms impacts from our past use of fossil and nuclear fuel, but, in both cases, we can avoid further use. These days we tend to focus on avoiding climate change and fossil fuel, but those tempted to see nuclear as an answer need to be reminded of what can go wrong- it can have wide ranging human costs and leave a long lived, brutal legacy:
New books on Chernobyl:
A movie:

The next post in this series will be on nuclear fusion- maybe not whole lot better.  

Monday, 1 April 2019

Fukushima 8 years on..

Eight years after the Fukushima nuclear disaster and two years after the Japanese government lifted evacuation orders in areas of Namie and Iitate, radiation levels remain too high for the safe return of thousands of Japanese evacuees. That is the conclusion of Greenpeace’s latest extensive radiation survey in Namie and Iitate, Fukushima prefecture.
In these areas, Greenpeace says ‘contamination will remain well above international maximum safety recommendations for public radiation exposure of 1 millisievert per year (mSv/y) for many decades’. Greenpeace includes projections on dose rates to mid-21st century, which it says ‘show that they will still be well in excess of the current government’s long-term target levels of 0.23 microsieverts per hour (μSv/h)’.  

Greenpeace notes that ‘in 2018, the Japanese government began a process to revise its current long-term decontamination target of 0.23 μSv/h’. It says ‘The major problem is that it is not attainable in many areas. It has been suggested that the new target would be in the1.0 μSv/h range. This is a politically motivated process with the aim of allowing the government to claim success in its decontamination program, which in reality has failed and which excludes the majority of contaminated areas which are forested mountains. Unable to set a date for when radiation exposure would be a maximum of 1 mSv a year in many areas, the government is seeking to shift the goal posts. This is a cynical disregard for public health protection & the human rights of Japanese citizens’.                                                                                                                         

It adds that in the case of radiation levels in the highly contaminated exclusion zone of Namie ‘it will be at least many decades for some areas, and well into next century for others, before radiation levels start to even approach government targets of 0.23 μSv/h. The Japanese government continues to disregard scientific evidence of cancer and other health risks from low-dose radiation exposure, including inthe range of 1-5 mSv/y. Yet the government has not only opened areas of Namie and Iitate where citizens will be exposed to rates equal to this and higher, but is also moving ahead with plans to open even higher radiation areas in the six municipalities of Futaba, Okuma, Namie, Tomioka, Iitate & Katsurao.’

Radiation levels still too high         

The results of Greenpeace’s 2018 extensive survey around houses, farmland and forest in the Namie exclusion zone reveal radiation levels that far exceed the government’s long term decontamination target of 0.23 μSv/h. It says ‘ the community of Obori, around 20 km west-northwest of the Fukushima Daiichi nuclear plant, is targeted as a reconstruction hub by the Japanese government with a target date for lifting evacuation orders in a small area in March 2023. Yet, in all of the survey work conducted by Greenpeace in October 2018, it was this area that showed the most extensive and consistently high radiation levels. In the community of Obori, we took 4,899 measurements with an average of 4.0 μSv/h and a maximum of 24.3 μSv/h. In the Obori hamlet, along a road and path where workers were operating on 23 October 2018, radiation hot spots were measured at 12 μSv/h at 1 meter, 19 μSv/h at 0.5 meters, and 64.9 at 0.1 meters. To put these figures into context, at this one location radiation readings at one meter were 300 times higher than the background level of 0.04 μSv/h in the prefecture before the March 2011 Fukushima Daiichi nuclear accident’.                                   

None of the zones, for which Greenpeace has complete data sets of radiation levels, have evidently seen a significant decline in radiation level during the period from 2016-2018. It says ‘explanations for these results include re-contamination through migration of radionuclides from the nearby contaminated forested mountain slopes. The inevitability of re-contamination from the forested mountains, which represent 70% of Iitate, as well as an equal proportion of Namie, is further evidence that the government’s limited decontamination program for thousands of homes has been, and will continue to be, ineffective in reducing the risks to citizens of Fukushima if they were to return to their homes’.                           

Greenpeace is also concerned about the working conditions of the clean up workers: In areas where some of these decontamination workers are operating, the radiation levels would be considered an emergency if they were inside a nuclear facility’.

Fukushima’s legacy

The debate over nuclear power and, more recently, over the impacts of Fukushima, has been long running, with a range of views emerging, for example of the scale of the health risk, including outside of Japan: 
However, what the new Greenpeace study reminds us is that, within Japan, the disaster is still happening – still having an impact. We don’t get to hear much about that any more, just the occasional snippet as deaths are admitted: Or new radiation hot-spots found: Or new health impact data emerges:

We do get to hear a bit more about Japans lackluster approach to developing alternatives  to nuclear- the government is dragging its feet and is apparently more concerned about getting some of the closed nuclear plant restarted, despite often strong local opposition.

The current plan (unlikely to be fulfilled) is to get nuclear back to 20-22% by 2023, but also to expand the use of renewable sources from the 82GW in place at the end of 2017 (including 50 GW of hydro), and maybe more like 100 GW in all now, given the recent PV growth, so that they supply 22-24% of Japan’s power by 2030. That is quite a low renewables target compared with some other countries (the UK is already at 33%, Denmark at 54%), but Japan started late in the push to new renewables, which only really got moving after Fukushima. Arguably it has not been trying hard enough. The impact of Fukushima evidently hasn’t been sufficient to overcome corporate and bureaucratic inertia. Perhaps the fact that renewables are now getting very cheap may change the situation. But meanwhile the slow, very expensive and maybe hopeless, decontamination process grinds on in the Fukushima area, while many ex-residents wonder when, if ever, it will safe to return.  And with it being unclear when all the radioactive debris will go:

The next post in this series will look at the situation at Chernobyl, with new studies suggesting that the incidence of cancer may be increasing, 33 years on…. Meanwhile, see this Chernobyl retrospective:

And also this Fukushima retrospective: