Radiation studies find new dangers of disease
By Bernard Wunsch
Since the advent of nuclear technology, people have been concerned about the effects of radiation on humans. The dangers of high levels of radiation were horrifically shown after the US bombing of Nagasaki and Hiroshima in 1945.
For years governments have been involved in trying to cover up the problems related to the nuclear industry. This year, anti-nuclear activists from Tahiti reported that hundreds of people suffering from cancer and other diseases have been taken to France for treatment, and birth deformities are appearing regularly. Yet the Tahitian government denies that this is a result of nuclear testing.
The Howard government's go-ahead to the Jabiluka uranium mine in Kakadu National Park and a new nuclear reactor in the southern Sydney suburb of Lucas Heights is also cause for concern given how much we already know about the dangers of radioactive waste.
However, evidence now suggests that there is no such thing as a harmless dose of radiation. This new information makes it all the more important for anti-nuclear activists and local communities to stand up against those who continue to lie about the nuclear industry.
Recent experiments indicate that low levels of radiation may not only cause more diseases than previously thought, but that this damage may be genetic and show up only in future generations. This means millions of people now and in the future are potentially at risk from radiation exposure considered safe under current levels.
This is another powerful argument against the mining and export of uranium from Jabiluka and other uranium mines.
The results of these experiments should challenge the idea that low levels of radiation are not a public health risk. The release of radiation from nuclear power plant accidents, nuclear waste dumping, testing and uranium mining may lead to increases in a range of diseases which may also affect future generations.
Studies of high levels of radiation which cause cancer and leukaemia have been well researched and accepted. Studies of survivors of the Hiroshima and Nagasaki bombings allowed researchers to determine how much radiation individuals were exposed to, what type of diseases they developed and the risks caused by high levels of radiation.
Longer term studies showed people dying of leukaemia after five years, while cancers of the thyroid, lung, breast and urinary tract started killing people after 15. Similar results turned up after the Chernobyl nuclear power plant disaster.
From this type of data, governments and nuclear proponents set a minimum level of exposure which they predicted would keep diseases caused by radiation to an acceptably low figure. Since then, it has been internationally accepted that people should not receive more than 1 millisievert of radiation in a year.
While the nuclear industry and governments have accepted these minimum radiation levels, many are less than happy to allow millions of people to be exposed when the long-term effects of such exposure have not been researched. Anti-nuclear activists have been active in opposing an industry which has proven to be dangerous and expensive and which still has no idea what to with its mounting radioactive waste.
Some radiation biologists, who did not accept governments' conventional approaches, began experimenting with low levels of radiation. The results are quite disturbing.
In several laboratories around the world they began looking into the mechanisms by which radiation affects cells and discovered DNA damage. The results were published in an article by Rob Edwards in the October 11 New Scientist.
Dr Eric Wright of the Medical Research Council (MRC) at Harwell, Oxfordshire, in England and other radiation biologists found in their experimental results that the concerns of anti-nuclear activists may be well founded — that there is no safe level of radiation exposure.
According to the article, Wright, who is the head of the MRC's Radiation and Genome Stability section, found a previously unknown pathway by which genetic material may be affected by radiation.
Wright says that radiation can inflict damage on cells that will be detected only after they have divided several times; he calls this "radiation-induced genomic instability". By this he means that radiation can make the genetic code (the DNA) of a cell unstable so that after it divides it shows damage. The cells most vulnerable to this kind of damage will be those that keep dividing, such as bone marrow, gut, skin and reproductive cells.
New Scientist explained that since this discovery in 1992, at least six other laboratories have confirmed this effect.
Wright's first experiment involved exposing stem cells (which keep the blood replenished with red and white cells) from the bone marrow of mice to plutonium-238 (used in nuclear reactors). This dose was low — equivalent to a single alpha (radiation) particle passing through each cell. After 11 days and between 10 and 13 cell divisions later, there were 3.5 times more damaged cells than in the unexposed control group.
This type of experiment has been tested with human lymphocytes, human breast cells, skin cells and also with mice reproductive cells. They all demonstrated much higher genetic damage in the irradiated cells.
New Scientist quotes Wright as saying: "There is really no doubt that genomic instability is a real consequence of radiation exposure".
One aberration the experiments have shown, however, is that cells from some mice were genetically more susceptible to radiation damage. These experimental results show that the damage to cells caused by low-level radiation can be detected only after cell division, but the precise mechanism is still unknown.
One of the most striking aspects of these results is the lack of information and experiments on low-level radiation exposure. The specific diseases which could be caused by this type of radiation damage, apart from cancer and leukaemia, are still unknown even though the effect has been proven to exist.
Some possible effects cited in New Scientist include foetus malformations such as cleft palates or deformed limbs, and brain diseases such as Alzheimer's, Parkinson's and motor neuron diseases. As yet the experimental evidence has not confirmed these suspicions. This is also being hamstrung by governments and the nuclear industry, which are keen to ensure that funding for such research is not forthcoming.
The article states that the radiation exposure may not cause a specific disease but could be responsible for damage to foetuses, hereditary diseases, cancers, accelerated ageing or immune system diseases.
The World Health Organisation has conducted an international workshop on genomic instability. Keith Baverstock, a senior radiation scientist with WHO, concurs with Wright in questioning the current regulatory system and warns that it may not be detecting diseases caused by radiation.
Genomic instability is now providing us with some clues to what governments previously called "aberrations". For example, it could explain why the children of workers exposed to radiation at the Sellafield nuclear plant in England have a higher chance of contracting leukaemia.
This could also be happening to workers in the nuclear industry, from uranium miners to technicians. It could explain other cancer and leukaemia clusters appearing around the world. But it also means that there are millions of people at risk of disease caused by radiation.