Uranium: a death sentence for miners

The Howard government's announcement that it intends to scrap Labor's three mines policy and allow the opening of new uranium mines in the Northern Territory, South Australia and Western Australia has renewed calls for an end to uranium mining by the environment and peace movements.

This article, abridged from a talk presented by Dr PHILLIP NITSCHKE to the Public Inquiry into Ranger Uranium Mine organised by Everyone for a Nuclear Free Future in Darwin on March 30, examines the costs to society of uranium mining from another angle -- the health of uranium mine workers.

Do uranium miners get cancer? The answer to that question is absolutely and unequivocally yes. There are two categories of risk for uranium miners. First are the direct effects: there is now irrefutable evidence that miners will be exposed to a significant risk of lung cancer as a direct consequence of their employment.

The results of research are starting to be consistent. In France, a 1993 paper titled ``The mortality of French uranium miners exposed to relatively low radon concentrations'' states that there is ``statistically significant evidence of lung and laryngeal cancer deaths''. Another paper from the US, titled ``Lung cancer in New Mexican underground uranium workers'', states that ``excess lung cancer is demonstrated, radon in underground mines remains a significant occupational hazard as the end of the twentieth century approaches''.

In Czechoslovakia in 1991 researchers looked at the risks of malignant neoplasms (cancers) of all types in workers in Czechoslovakian uranium mines. They concluded that it was necessary to restrict uranium mining because of the high medical risk.

Perhaps the most important result is Woodward's 1991 research into the health consequences for workers at the Radium Hill mine in South Australia, which operated for about 10 years. Woodward found that lung cancer mortality was markedly higher among underground mine workers.

The proposed new uranium mine at Jabiluka will be underground, so the issue of health effects in underground mines has to be looked at very closely in Australia today. It has taken some time to absolutely establish that the workers in underground uranium mines had a significantly increased chance of developing one type of cancer at least, lung cancer.

Lung cancer takes a long time to establish itself, and it takes time for researchers to absolutely establish the cause and effect between the occupational hazard and the disease. So even though these mines may have been operating for 10 or 20 years, the earliest that we could have established the health consequences is now, and that's exactly what's happening.

The health consequences of those earlier mining operations are being revealed and published in very specific detail for everyone to see. The conclusion is clear: if you worked as a uranium miner in those earlier years, you have a significantly increased risk of developing cancer.

It is the inhalation of radon, one of the radioactive by-products that accumulates as a gas within the underground mine, which is thought to be the cause of the development of this particular lung cancer. When you are mining uranium underground, it is not so much the radiation coming at you from all directions that's the issue, but the fact that radon gas exists in a concentrated form in those confined spaces. This gas is mixed up at an atomic level with the air that miners breath. There is no way to filter it out. I will come back to this.

The second category of risk, the indirect cancer risk, is more contentious. There are no clear answers in this area, but there are an awful lot of unanswered questions.

Information has come to light in the last few years which shows that men involved in industries where they are exposed to radiation father an increased number of children with leukaemia. This information, which has come to be known as the Sellafield results, has been debated for the last few years, and still is.

In the 1980s, an epidemiologist called Gardiner, working in the UK around the Sellafield reprocessing plant, noticed that there was an increased rate of leukaemia among children in the immediate vicinity of the reprocessing works. At first people thought that this was probably due to the children's exposure to some form of environmental contamination which was getting out from the reprocessing plant.

But what Gardiner found did not fit the distribution rates that he observed. What did fit was the radiation exposure that the fathers of these children had received immediately prior to the conception of the children. He found that for workers who received cumulative radiation doses of 100 millisieverts before conception, the risk of fathering a leukaemic child was six to seven times higher than normal. For those receiving a dose of 10 millisieverts in the six months prior to the child's conception, the risk was seven to eight times.

Because these are relatively low doses of radiation, the results sent a shock wave through the scientific community and the occupational health communities around the world. Sellafield unions immediately advocated a significant reduction in what was deemed a ``safe'' level of radiation exposure for workers.

There is no easy way to explain the Sellafield results. They don't fit scientists' understanding of how radiation impinges on the body -- that is, that it changes some cells and produces cancer some 20 years later. There is also no apparent explanation for the fact that the fathers didn't seem to be getting any cancer but the children did.

In the consequent outcry in the scientific fraternity, a lot of inquiries and studies were set up to try to find out just what the findings meant. Every piece of research since that time has tended to pour cold water on Gardiner's results. No-one in any way refutes them, they just can't explain them. The situation is a little bit like we were in 20 years ago when we couldn't actually establish that the workers in underground mines were getting lung cancer, but there was a lot of anecdotal evidence that they were.

Nevertheless, the one thing that was clear was that there had to be an immediate downward revision of the ``safe'' levels at which workers could be exposed to radiation.

The question of radiation standards is a rather complex and vexed one. The bases for setting radiation standards can be divided into external exposure and internal exposure.

External exposure measures the amount of radiation which impinges on the body, usually the whole body, as a result of simply being in a particular environment. If you are standing on a part of the planet where there's a high background radiation, the radiation coming on to your body is predominantly in the form of gamma rays. Its effect on the human body is measured in a unit called millisieverts.

Scientific attempts have been made to work out at what level of external radiation there is an increased risk of cancer. On this basis, judgments have then been made regarding at what levels the cancer risk is considered to be ``acceptable''.

The level considered acceptable has changed dramatically over the 100-year history of the uranium mining industry. In 1900, it was believed safe for a worker to be exposed to 100 millisieverts of radiation per day. By 1925, the figure had dropped to 5000 millisieverts per year. The latest recommendations of the international body commissioned to develop these units, the International Commission for Radiation Protection (ICRP), reduced it to 20 millisieverts per year in 1990. Of course, the ICRP figure is only a recommendation. It is up to individual countries to decide whether or not to adopt these standards.

It should be noted too that this figure is an average: it accepts the fact that workers may be exposed to more than 50 millisieverts in one year in some situations so long as they do not receive more than 100 millisieverts over five consecutive years.

There are a number of principles which underlie the setting of this standard. The first is that there needs to be justification whenever someone is exposed to any radiation.

The second principle is that exposure should always be kept as low as possible. There is no such thing as a safe level of radiation, but the thinking behind setting an international standard is that there may need to be a trade-off in the national interest (e.g. export income) or in the interest of the individual (e.g. higher wages perhaps).

Thirdly, these recommended limits are meant to be top limits; radiation exposure should be kept as low as possible below that. The principle of additivity applies here; that is, if someone gets radiation from one source and then again from another source, it is recognised that they are additive (some would even say multiplicative), and cannot be separated.

It is on the basis of this principle that we should be calling for a national register of all people exposed to radiation in the industrial work place. It is impossible to keep track of workers moving from mine site to mine site unless there is a register which records people's total accumulated radiation dose.

The important point about the changing levels of "acceptable" radiation exposure over the history of uranium mining is that the trend has always been downwards; in fact, recommended levels have reduced dramatically. There is a lot of information (like the Sellafield results) that we still don't understand, but as we understand it more, it is likely that the millisieverts per year level set now will turn out not to be a safe level at all.

Australia has been remarkably slow to implement the 1990 ICRP recommendation. For the last six years, the radiation level which workers could be exposed to in Australia was not 20 but 50 millisieverts per year. The ICRP's 1990 recommendations must be adopted in Australia immediately.

The specific dangers associated with radon gas exposure have resulted in the development of a specific internal exposure level standard associated with the ingestion of radioactive material.

This standard quantifies the risk for workers inhaling this radioactive gas in terms of working level months (WLM). Risk levels are determined by the concentration of radon gas that is breathed and the length of time it is breathed for.

There are only two ways to reduce the risk in this area. The first is to limit the amount of time workers breathe the stuff by, for example, rotating workers in and out of the area. However, this measure is the subject of debate since, if there is no radiation exposure threshold below which you don't get cancer (that is, if there is no safe exposure level), then rotating workers through the mines would simply spread the numbers of cancer amongst a bigger pool of people.

Nevertheless, as far as the mine operators are concerned, the rotation method reduces the workers' exposure to below the official or "public worrying" level, although it is an expensive strategy requiring mines to have a larger pool of workers.

Alternatively, the level of radon concentration in the mine can be lowered. A lot of strategies have been tried to achieve this, perhaps the simplest being to blast air from large air circulation plants through the underground mine site.

In 1986, the ICRP limit of 50 millisieverts of radiation exposure was translated as being equivalent to five WLMs. When the ICRP reduced the limit of 20 millisieverts in 1990, however, the recommended WLM did not change. For underground miners, then, the level of risk that was considered safe in 1986 is still considered acceptable.

The reason for this anomaly is probably that complying with lower WLM levels would be very expensive, possibly making the difference between profitable and unprofitable mining operations.

Nevertheless, it is coming to light that the diseases that uranium miners are now experiencing are very specifically associated with their work history. It is probable that, as has happened in the case of mesothelioma in asbestos workers, uranium miners are going to start demanding compensation for the life-threatening diseases that their workplace exposed them to.

Those compensation claims might just tip the scales and knock the economic strength out of a pretty marginal industry. [Phillip Nitschke is a member of the Medical Association for the Prevention of War and was a Senate candidate for the NT Greens in the last federal election.]

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