Found: a cause of leukaemia?
report from Radioactive Times Volume 3, Number 2, October 1999 (content not updated)
LLRC research has been increasingly directed toward the exposure route which involves inhaling dust and particulate matter. As readers of Radioactive Times will recall (Vol 3, No 1, March ‘99), research aimed at examining the risk of cancer by distance from the Irish Sea focused on close proximity to the radioactive mud banks that have formed in certain coastal areas as a result of the fractionation of fine radioactive particles containing plutonium and other isotopes from Sellafield. The question has been: how can the radioactive particles get into the people and cause cancer?
Harwell and MAFF
The answer begins with measurements made by scientists from Harwell and MAFF in the 1980s. These measurements showed two things. First they showed that the fond belief that the discharges would either become dispersed by dilution or else safely bound to sediment on the sea bed was wrong. The radioisotopes did became bound to the fine sediment but this was coming back to the land.
The phenomenon was called "sea-to-land transfer". Appreciable concentrations of Plutonium-239 were measured in air up to 30 miles from the Cumbrian coast. But other measurements showed something truly alarming. The concentration of Plutonium-239 in grassland suggested that radioactive particles from Sellafield were contaminating practically the whole of Britain.
Measurements made on sheep faeces at points from Cumbria to Whitby on the East coast of England showed the presence of Sellafield Plutonium across the whole country. The heavier particles fallout inside the first ten kilometres, a finding that supported the suggestion that this was the cause of the Welsh coastal effect on cancer and leukemia. The trend with distance is so interesting that it is shown in Figure 2 (under construction).
The second piece of information that ties the particles to the cancer increases in Wales is the discovery that the small areas most affected, are those where the tidal conditions have favoured the formation of the largest areas of radioactive mud, e.g. Bangor and the Lavan Sands. Since all these studies in the 1980s were showing that sea-to-land transfer of radioactive particles was occurring, the possibility that this might be causing harm must have occurred to someone.
As everyone knows by now, NRPB are essentially modellers: they will always try to mathematically model an effect before actually looking out of the window to see what is happening. After the surprising discovery that the radioactive discharges were behaving in this unsporting way and finding their way back home NRPB were asked to look and see where their models had gone wrong. They set up a programme of measuring plutonium (and later Caesium) in hundreds of autopsy specimens from across the UK. The man in charge was Don Popplewell. He has now retired but his assistant, George Ham told us that it was a very messy business. What they found was rather alarming.
The highest concentrations of plutonium were in the Tracheo- Bronchial Lymph Nodes or TBNs. This was unexpected since the accepted ICRP and BEIR IV models were based on the idea (plucked from thin air) that inhaled plutonium was mostly mobilised out of the lung, swallowed and passed harmlessly through the alimentary system. Plutonium was effectively insoluble and not absorbed across the gut wall. Its exposure to the lining of the gut was minimal since it was an alpha emitter. But what was the plutonium doing in the TBNs? And what was it doing to the TBNs? The concentrations could be quite large (see Table 1).
Table 1. Activity mBq/Kg (wet) of Plutonium-239 + 240 in lung and Tracheobronchial lymph nodes in US and UK populations living near nuclear sites, and average populations. From:
population LUNG TBNs Los Alamos 20 160 US average 7 100 Cumbria 7 35 UK average 2 10
(UK) Popplewell, D., NRPB Radiological Protection Bulletin, No. 74 (1986);
(US) McKinroy, J. F., et al Health Physics 37 1 - 137 (1979)
By the early 1990s the question of the child leukemia excess near Sellafield had become important. There was the Reay and Hope court case. Martin Gardner had implicated the fathers of the children in transgenerational genetic damage. There were public inquiries into THORP, all sorts of activity of a questioning nature.
NRPB were running around in circles trying to develop the ontological proof of the safety of Sellafield. Finally they produced the closest they could to this, the follow up to their 1984 analyses R171, their ultimate new improved, super radiation kleener, reaching the exposure routes no other kleener can touch, killing all anti- nuclear activists.
The report was R-276 Risk of Leukemia and other Cancers in Seascale from all Sources of Radiation Exposure. But they were not the only organisation doing this.
After Yorkshire TV’s discovery of the Seascale cluster, the government inquiry under Sir Douglas Black promptly confirmed the existence of the 10-fold excess of child leukemias (3-fold excess of childhood cancers). But Black had to pretend to believe the NRPBs calculations on dose and effect. As we know, the Hiroshima ‘Lifespan Study’ figures were used to derive a Risk Factor and this factor showed that the average dose from Sellafield discharges was too small to cause the leukemia excess.
Black was clearly not persuaded by the science in NRPB R171. How could the largest source of radioactivity in Europe not be the cause of the local excess of a disease whose only known cause was radioactivity? He recommended setting up two new bodies. The first of these was the Committee on Medical Aspects of Radiation in the Environment or COMARE. Their job was to check out the science. (For the second: the Small Area Health Statistics Unit, SAHSU see story on page 9).
COMARE studied the issue and produced their independent report in 1986. Sadly, this did not attempt to assess the science but largely following the lead of NRPB’s R- 171.
Their method was, again, the classic mathematical model. Using averaging, some quantity of discharge was diluted into the environment. Using averaging, some quantity of environment was diluted into the children. This dilution process kept the doses small and the children were proclaimed safe.
Fear in a handful of dust
COMARE returned to the issue of the Seascale children in 1996 with their Fourth Report. This followed the NRPB R-276 update mentioned earlier both in time and in analysis. The general intention was to convince everyone that the problem had gone away. Martin Gardner had died and Leo Kinlen had shown that the cause of the clusters was ‘population mixing’. Sellafield was now really safe. Hurrah!
But because the sea-to-land transfer had become a reality, the question of the lymphatic doses had to be addressed in more detail.
On page 76 COMARE IV acknowledges:
Both the Black committee and COMARE I had looked at the doses to the tracheo-bronchial lymph nodes as it was known that these could be the site of origin of leukemia and lymphoma in laboratory animals and they are sites which could be exposure to inhaled radionuclides.
COMARE asked NRPB to calculate the doses to the TBN’s. This is where the fun begins.
Crazy calculations or no calculations
The results of NRPB’s calculations are also given on page 76 of the report (COMARE 4). They show that the alpha dose to the TBN of an an infant aged 1 year integrated to 25 years is in the worst year, 1955, seven times that from ‘Natural Background’.
There are two immediate problems with this calculation.
The first is that an infant aged one year is a strange choice of model since the parameters of infants given by ICRP for their model are very different from those of two to twenty five year olds. The infants breath through their noses, they are indoors and have very small lungs. Older children are mouth breathers, are outdoors and have larger lungs.
The second is that in comparing the Sellafield dose with the Natural dose they have put Uranium in the Natural column. Near Sellafield, the Uranium may have once been natural but its levels are mostly due to Sellafield activities. Also the doses should be cumulative. Plutonium in the lymph nodes mostly stays there. Each addition of plutonium adds more dose. [see also this link]
The cause of leukaemia?
So the real doses, even using NRPB’s averaging, are the highest they found in any organ by any exposure route. We contacted COMARE to ask how the calculation was done. Bryn Bridges emailed Chris Busby: The calculations are in R-276, he wrote.
‘But no’, replied Busby, ‘ they are not!’
Bridges apologized: I was misinformed. They are in a report by NRPB COMARE 95/40 by J.R.Simmonds.
Can we have a copy?
No, it is a private report of NRPB!
So the origin of the Seascale child leukemias is now down to an explanation based on an unpublished report which is not available for review? We contacted Frances Fry at NRPB.
No, the report is not available, it has not been internally reviewed.
Good, we said, just put that in writing please and sign it.
The report appeared the next day with a caveat by Ms Fry: It should not be cited because it hasn't been checked.
But why then was it used by COMARE to support their conclusion that radiation from Sellafield had not caused the leukemia excess? Why did we see Bridges on TV telling us in 1996 how it was an unknown virus brought in by workers and spread by open sewage facilities?
The report, in any case tells us nothing. It is one page containing the message that the doses were calculated for a 1 year old and giving the result. No explanation of parameters, no equations or input values. Nothing.
We believe that one cause of the Sellafield leukemias is now probably found. It is the high local dose to the TBNs. Because NRPB calculate their doses by dividing the energy from the plutonium decays into the whole of the lymphatic system. In R-276, they model this as liver, lung, kidney, spleen, pancreas, uterus and intestines. No physiologist would recognise this large mass of organs as a description of the lymphatic system.
Mouth and nose breathers
From coastal leukemia in Wales to sea-to-land transfer we have moved on to TBNs and we are back at averaging of local doses. As RaT readers will know we have flagged up the dangers of radioactive dust elsewhere, in explaining the Aldermaston and Harwell leukemias and in the clusters near power lines and earth electric field discontinuities along geological strata. New towns are a great source of radioactive dust, with the building works. Farmers and builders suffer dust and also from high levels of leukemia. The peak in childhood leukemia at 4-years follows changes from indoor nose breathing to outdoor mouth breathing. We can continue to slot all the observations into the hypothesis. Certainly, the idea has a great deal more going for it than the explanations of Leo Kinlen and Sir Richard Doll.
LLRC has requested the parameters and methodology of the lymph node calculations.
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