Canadian Coalition
for Nuclear

Regroupement pour
la surveillance
du nucléaire


A Discussion Guide


by Dr. Gordon Edwards et al.

prepared for and published by
The National Film Board of Canada

to accompany the film "Uranium"
directed by Magnus Isacsson

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F.1. What are uranium tailings?

In mining, the uranium and its decay products buried deep in the earth are brought to the surface, and the rock containing them is crushed into a fine sand. After the uranium is chemically removed, the sand is stored in huge reservoirs. These left-over piles of radioactive sand are called "uranium tailings".

Uranium tailings contain over a dozen radioactive materials which are all extremely harmful to living things. The most important of these are thorium-230, radium-226, radon-222 (radon gas) and the radon progeny, including polonium-210.

If this radioactive sand is left on the surface and allowed to dry out, it can blow in the wind and be deposited on vegetation far away, entering the food chain. Or it can wash into rivers and lakes and contaminate them.

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F.2. What is thorium-230?

Thorium-230 is the uranium decay product with the longest lifetime. It lasts for hundreds of thousands of years -- in human terms, forever. Thorium is especially toxic to the liver and the spleen. It has been known to cause leukemias and other blood diseases. It decays to produce radium-226, which in turn produces radon gas (radon-222).

So the amount of radium in the waste, and the quantities of radon gas produced by it, will not diminish for a long time, because they are constantly being replenished by the decay of the very long-lived thorium-230.

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F.3. What is radium-226?

Radium-226 is one of the more dangerous of the uranium decay products. It is a radioactive heavy metal, and a potent alpha emitter. As it decays, it produces radon gas as a byproduct. Radium is chemically similar to calcium, so when ingested, it migrates to the bones, the teeth and the milk. It is readily taken up by vegetation. In aquatic plants, it can be concentrated by factors of hundreds or even thousands.

In the first half of the twentieth century, radium was used to make a paint that glows in the dark. Radium is now considered too dangerous to use for such purposes. Many young women who used the paint in their work died from cancers of the bone or of the head. The bone cancers were caused by microscopic amounts of radium which were unintentionally swallowed. The head cancers resulted from radon gas generated inside the women's bodies which collected in their sinus and mastoid cavities.

Today, it is considered dangerous to wear a watch whose numerals have been painted with radium paint, because some of the decay products give off intense gamma rays, even more powerful than x-rays. This type of radiation can damage the body by sending rays right through it, even from a distance. Indeed, radium is sometimes used in cancer therapy for this very reason, to destroy unwanted tumours.

While some radium is still used for medical purposes, only small quantities are needed. Most of the world's radium is now discarded with the crushed rock left over from uranium mining, despite the fact that it is known to be a hazard.

Several U.S. studies have reported higher rates of cancer and leukemia in communities having elevated levels of radium in the drinking water, although the cause-and-effect relationship in these cases is still a matter of dispute.

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F.4. What is radon-222?

Radon-222 is a toxic gas created by the decay of radium-226. Most of the radon is normally trapped in the ore-bearing rock deep within the earth. But when the rock is excavated and crushed, a lot of radon gas is released into the air. The uranium miners breathe this radioactive gas and its progeny into their lungs.

Radon (the gas and its progeny) is a very powerful cancer-causing agent. Even small doses inhaled repeatedly over a long time can cause lung cancer.

Uranium tailings are constantly producing large amounts of radon gas through the decay of radium in the tailings. This gas can travel thousands of kilometers in a light breeze in just a few days. As it travels, it continually deposits solid radon progeny on the ground, water and vegetation below.

Radon also dissolves readily in water, and can be transported by ground water into wells and streams.

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F.5. What are the radon progeny?

Because radon gas is radioactive, it decays, producing seven radioactive decay products called "radon progeny". These solid radioactive materials attach themselves to tiny dust particles and droplets of water vapour floating in the air.

CHART: Radon Progeny

How Radon Gas Produces Radon Progeny
through Radioactive Decay


The vertical axis measures the MASS NUMBER,
while the horizontal axis measures the ATOMIC NUMBER.

DIAGONAL ARROWS indicate alpha decay
while HORIZONTAL ARROWS indicate beta decay.

It is a measure of the ENERGY of the alpha radiation.
The more energetic it is, the more damaging it is.

By itself, radon gas is exhaled as easily as it is inhaled; but when the accompanying radon progeny are inhaled, they lodge in the lining of the lung. There they bombard the delicate tissues with alpha particles, beta particles and gamma rays. The radon progeny are various radioactive forms (or "isotopes") of bismuth, polonium and lead. The bismuth and lead isotopes emit beta particles and intense gamma rays, while the polonium isotopes emit alpha particles which irreparably damage the bronchial tissue.

When radon gas is given off from uranium tailings (see F.4) the radon progeny eventually come to earth as radioactive fallout, in the form of rain, snow or dust, entering aquatic and terrestrial food chains. A few days following deposition, the only progeny left are lead-210 and polonium-210; the others have decayed away to almost nothing.

When lead-210 and polonium-210 are ingested in contaminated vegetables, fruits, fish or meat, they are incorporated into the body just as non-radioactive materials are.

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F.6. What is polonium?

Three different isotopes of polonium are included among the radon progeny. They are polonium-218, polonium-214 and polonium-210. These pernicious substances are responsible for most of the biological damage attributed to radon. In particular, polonium-214 and polonium-218, when inhaled, deliver massive doses of alpha radiation to the lungs, causing fibrosis of the lungs as well as cancer.

Animal studies have confirmed that polonium is extremely harmful, even in minute quantities. The 1988 BEIR-IV report states that polonium-210 is far more dangerous than plutonium at high exposure levels, is more or less equivalent to plutonium (which is five times more damaging than radium) at intermediate exposure levels, and approaches the toxicity of radium at very low exposure levels.

Because of the lichen-caribou food chain (mentioned in C.3), caribou in the arctic and in northern Saskatchewan have much higher levels of polonium-210 in their flesh than any other animals in North America. As a result, the Canadian Inuit have up to 80 times more polonium-210 in their bodies than other North American people do. Uranium mining can only exacerbate this situation, because increased amounts of airborne polonium-210 will be deposited on the lichen as fallout from the tailings and from abandoned ore bodies.

There is growing evidence that polonium-210 inhaled in tobacco smoke is responsible for much of the biological damage caused by cigarettes. Autopsies show that smokers have higher levels of polonium-210 in their lungs than non-smokers. Animal studies show that polonium-210 in the lungs is a superb carcinogen. From the lungs, polonium can also enter the bloodstream; the resulting radiation damage to blood vessels can eventually lead to blocked arteries, causing strokes and heart attacks.

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G.1. What are the greatest environmental risks from a uranium mine?

The greatest risks to the environment are (1) contamination of ground water and river systems with dissolved radioactive materials; (2) catastrophic failures of tailings containment; (3) the dispersal of radioactive dust, which finds its way into water, plants, animals, fish and humans; (4) releases of radon gas into the air, which will deposit radon daughters on the ground for hundreds of miles around; (5) pollution of surface and ground water by chemical pollutants in tailings, notable heavy metals, acids, ammonia and salts.

In the short term, chemical pollution has caused by far the most damage. Whole groups of organisms have disappeared downstream from some uranium tailings areas. Radiation hazards are more subtle and will take longer to be manifested.

Unless the tailings are properly disposed of, these hazards will continue unabated for thousands of years. Tailings hazards will probably get worse as time goes on because of erosion, neglect and climatic change.

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G.2. Does uranium mining cause water pollution?

During routine mine and milling operations, radioactive substances and other chemical contaminants (including sulphuric acid) will escape into the water. In Ontario, the entire Serpent River system -- including more than a dozen lakes -- were badly contaminated for 55 miles downstream from the uranium mines in the Elliot Lake area by the late 70s. At that time, the International Joint Commission identified the Serpent River system as the largest single contributor of radium contamination to the Great Lakes. The situation has improved since then as corrective measures have been taken.

In case of a failure of the containment system for tailings, rivers and lakes can be ruined completely as a source of water for humans and animals. In the Elliot Lake area, there have been over thirty tailings dam failures. In 1979, a new tailings dam built with the latest technology suddenly collapsed in Churchrock, New Mexico; the resulting spill was the greatest accidental release of radioactive material into the environment prior to the Chernobyl nuclear disaster.

At Key Lake in Saskatchewan, there were more than half a dozen radioactive spills within six months of the mine's starting operations in 1985. The main problem at Key Lake is that the tailings area is too small, even though it is a modern mine.

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G.3. What dangers do tailings pose to humans, wildlife and the environment?

Unless uranium tailing are perfectly contained in some kind of storage system which has yet to be devised, humans and animals who come close to the tailings cannot help ingesting or inhaling some of this radioactive material, which seeps into the air, the food and the water. In this way, damage can be done to the lungs, skin, kidneys, blood, bones and reproductive organs. Over a period of years, that damage can lead to many types of illnesses, including cancers and leukemia. It can also lead to diseases and malformations in children, even before they are born.

A major study of Navajo Indians who worked as uranium miners, and those living near uranium tailings on the Colorado plateau, is almost finished. The children of these people have a very high rate of birth defects. A study in Malaysia is currently documenting changes in blood and ill health among children exposed to thorium and uranium waste.

Radioactive materials in the tailings can also be carried very far away in the bodies of animals, fish, birds, and insects. Anybody eating the meat from contaminated animals will get the radioactive material inside his or her own body.

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G.4. Is there a way to avoid this kind of radioactive contamination?

Since people have to breathe and eat and drink, it is impossible to avoid the radioactive material once it is released from the deep rock and brought to the surface and crushed and spread into the environment. The only remedy is prevention. Either the crushed rock should not be allowed to get into the environment, or the radioactive material should not be brought to the surface.

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G.5. How long will the tailings be radioactive?

The uranium which is taken away and sold represents only about one seventh of the total radioactivity in the rock. The rest will be left in the tailings, which will remain dangerously radioactive for hundreds of thousands of years -- far longer than the span of recorded human history.

In fact, the amount of radium in the tailings, and the amount of radon gas given off by the tailings, will not diminish much for the first 5,000 or 10,000 years. (The Egyptian pyramids are about 5,000 years old.) Even after 80,000 years, these quantities will have diminished by only one-half.

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G.6. How long will it take to get rid of the hazard of uranium tailings?

Unless a great deal of money is spent on engineered deep storage of the mine and mill tailings, they will be left at the mine site forever. No mine or mill site has yet been cleaned up in a permanently satisfactory way anywhere in the world.

New stringent laws for covering (but not burying) mine and mill tailings in the U.S. have made mining companies move away to other countries where there are no such detailed laws. Canada does not yet have detailed laws requiring the removal or covering of mine and mill tailings by the mining companies, nor does the Canadian government require deep burial in rock. In most cases, Canada does not even fence in the abandoned radioactive material or post signs to warn people that it is dangerous.

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G.7. Can modern science eliminate atomic radiation from radioactive tailings?

Modern science has no way to eliminate this radiation. There is no practical way to neutralize radioactive materials, to destroy them or to render them harmless.

Attempts are underway to try to put radioactive mine and mill tailings back into the ground, like the ore from which they originated, because the radioactive materials in the tailings were less harmful to animals and humans when they were underground.

However, we do not know how to put the sand back together as a rock, nor do we know how to call back all the radon gas, the liquid effluents and the radioactive dust which have been released into the environment. Because the finely ground tailings are much more easily dissolved than the original ore, we cannot ensure that ground-water contamination will not occur following burial. Also, because the tailings will remain dangerous for a period of time which exceeds the span of human history, it is difficult to judge whether our storage methods will be adequate.

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G.8. What are the long-term effects of uranium mining? [Dr. Stella Swanson]

What is known:

  • Radionuclide content in aquatic biota (fish, insects, clams, plants) has been shown to increase downstream of uranium mine tailings; this increase is especially pronounced near older mines.

  • Radionuclide content in terrestrial plants near uranium mines and mills increases; again this increase is more pronounced near older mines.

  • Uranium series radionuclides do concentrate in plants low on the food chain but they do not biomagnify; that is, they do not increase in concentration as they are passed to successive steps in a food chain. Thus, they do not behave like mercury. This is fortunate for top predators, such as people; however, it does not mean that people or other animals at the top of the food chains get no radiation dose at all; just that it is much lower than it could have been had the radionuclides behaved like mercury. Furthermore, effects on biota at the bottom of food chains (where doses are higher) may have long-term ecological consequences.

  • Significant levels of radionuclides released during atmospheric bomb tests were found in caribou and reindeer in arctic regions in the late 1960s. Since then, data have shown the levels to be in steady decline. However, there have been no studies specifically focussing on animals who migrate into uranium mining areas and no recent studies tracking uranium-series radionuclides in sensitive arctic foodchains.

  • There are several other contaminants released by uranium mines; these can include arsenic, nickel and unnaturally high levels of salts. Some uranium tailings are also very acidic, leading to the release of more metals into the environment.

  • Improved treatment of uranium tailings at mines opened since 1980 has significantly decreased the rate of release of radionuclides and metals into the environment.

  • Estimated radiation doses to people eating fish once a week from a lake contaminated by an older uranium mine are 1 to 2 percent of the annual radiation dose limit for the general public. These are worst case estimates. The significance of such doses is subject to debate because it involves judgment as to the acceptability of any risk from radiation, as well as disagreement over the science used to derive the dose.

What is unknown:

  • We do not know what effects chronic exposure to low level radiation has on biota and ecosystems as a whole. We can guess, based on laboratory experiments using higher dose radiation of a different quality; however, we have no real data from the field.

  • Until recently, protection of people from radiation has been assumed to protect all other forms of life. This premise is now being questioned. A more ecosystem-centred approach may be preferable.

  • We do not know enough about radionuclide levels in game animals routinely consumed by people living near uranium mines.

  • We do not know how to decommission uranium mines so as to minimize radionuclide migration for millennia; uranium mines that have been decommissioned need further detailed study.

  • We do not know the significance of other contaminants released by uranium mining. They may be more damaging to indigenous biota than radiation.

One of the central problems in the debate about the nuclear fuel cycle is ignorance. Scientists simply do not know what the effects of chronic exposure to low-level radiation are, either in people or in other biota. We can guess, based on extrapolations from victims of high-level radiation such as atomic bombs and nuclear reactor accidents like Chernobyl. We will only begin to know for sure after several more decades have passed and a large population of exposed people has been studied. In the meantime, we have to ask: "Do we really want to live with this uncertainty? What risks are we willing to accept as a society?"

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H.1. Who is responsible for regulating tailings management in Canada?

As long as the uranium mine/mill complex is operating, the management of the tailings is regulated by the Atomic Energy Control Board (AECB) and by the appropriate provincial authorities. However, once the tailings have been abandoned, particularly when the owner/operator ceases to exist or disappears, there is considerable confusion as to who is responsible for managing the tailings.

There have been numerous cases in Canada and elsewhere where hundreds of thousands of tonnes of radioactive mine tailings or refinery wastes, neglected by the authorities, have been used in the construction of homes and schools, resulting in unacceptably high levels of radiation exposure in those buildings. In Ontario, there are several cases of abandoned uranium tailings which are still not properly fenced or posted with adequate warning signs. These vast stretches of radioactive sand are freely accessible to animals, bikers, children, berry-pickers and picknickers. There is also the ever-present danger that this innocuous-looking sand will be used as fill or in home construction.

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H.2. What do the regulations require?

The regulations require the design, construction, maintenance and monitoring of an engineered facility for storing tailings as long as the mine/mill complex is operational. There are also requirements for treating effluents and limiting access to the site, and there are close-out criteria to be followed in preparing the tailings for abandonment.

During the operational phase, the tailings must be physically confined behind some kind of retaining wall. The regulations require that provision be made for controlling the blowing of radioactive dust and limiting the atmospheric releases of radon gas. In addition, design measures to prevent the seepage of chemicals and radionuclides into the underlying soil, and to reduce the levels of radioactivity in the liquid run-off, must be approved. In unusual cases, where some portion of the tailings contains unusually high concentrations of radioactivity, special design requirements may be laid down by the regulators.

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H.3. Are the regulations effective?

Over all, tailings management during the operational phase has greatly improved in the last fifteen years. Nevertheless, even at the newest mines, radioactive spills are frequent. Inspectors are not highly trained, and they often fail to notice flagrant violations of the regulations.

The long term containment of uranium tailings remains a major unsolved problem. Two of the most significant failures occurred in 1979, at Churchrock, New Mexico, when (as already mentioned) a huge state-of-the-art tailings dam collapsed without warning, and in the early 1980's, at Cluff Lake, Saskatchewan, when efforts to store highly radioactive tailings in thousands of concrete "pots" ended as a dismal failure. Although the pots were supposed to last for centuries, dozens of them were found to be cracked and leaking after less than five years of use.

Once uranium tailings have been abandoned, it is doubtful whether any regulations can be effective in preventing large-scale contamination of the environment. The levels of radioactivity in the tailings, and the amount of radon gas produced by the tailings, will not noticeably diminish for more than 10 000 years. How can the natural forces of erosion, migration, dispersion and dissolution be held in abeyance? Who will monitor the wastes and take corrective action? And who will pay for the future effort needed to do all this?

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H.4. Are the regulators independent of the industry?

The Atomic Energy Control Board (AECB) is supposed to be independent of the nuclear industry. However, it reports to the federal Minister of Energy, Mines and Resources -- the same Minister who is responsible for Atomic Energy of Canada Limited (a crown corporation that designs, builds and sells nuclear reactors) and Cameco (formerly Eldorado Nuclear Limited, another crown corporation that owns and operates uranium mines and refineries).

Moreover, most AECB staff are drawn from various sectors of the nuclear industry, including the uranium companies. In the past, many of the Board members were representatives of the very industries that AECB is regulating. Formal public hearings are not required as part of the licensing process, nor have such hearings ever been held.

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J.1. Can the human body protect itself from radioactive materials?

The body has no way of protecting itself from radioactive substances in food or air. It takes them in and stores them in the lungs, muscles, bones and other organs, just as if they were natural foods.

Inside the body, when the radioactive material decays, it explodes (microscopically), causing damage to the tiny living cells. When many of these cells are damaged, the body is less able to fight off a variety of infectious diseases.

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J.2. How does atomic radiation cause cancer?

Chronic illnesses -- including leukemia or cancer -- can be caused by atomic radiation. When cells are damaged in such a way that they begin to reproduce in an abnormal and uncontrolled fashion, they have become cancer cells. As the cancer spreads, it destroys healthy tissue, and unless arrested, it eventually kills the host organism. Leukemia is a cancer of the bone marrow, which results in the uncontrolled overproduction of white blood cells to the detriment of other blood cells.

It takes time for a cancer to grow, so the effect is not apparent immediately. It often takes many years before cancer caused by breathing radioactive air or eating contaminated food can be spotted by a doctor. Even then, it is usually impossible for the doctor to tell whether that specific cancer was caused by atomic radiation.

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J.3. How does atomic radiation cause genetic defects in children?

Radiation damage to the father's sperm or the mother's eggs can result in a damaged child. Atomic radiation workers, such as uranium miners, take the greatest risk of having a damaged child because they are in closest contact with radioactive materials. A child suffering from genetic damage can pass that damage on to future generations.

Since the father's sperm is replaced every three or four months, he could theoretically wait for some time after working in the mine before fathering a child. However, if his body is contaminated with long-lived radioactive materials, his sperm could continue to be damaged by internal exposure to radiation even after quitting his mining job.

Women carry in their bodies from birth, all the eggs they will ever have. Damage to a woman's eggs at any one time can result in a damaged baby many years later.

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J.4. How do we know that atomic radiation causes genetic damage?

Genetic damage has been observed and documented in every laboratory species that has been so far studied, including mammals, insects, micro-organisms and plants.

Genetic damage sometimes results in an unviable organism, leading to spontaneous abortion or premature death. Some kinds of genetic damage result in gross abnormalities or deformities, whereas other types involve subtle differences which are difficult to detect. In fact, some forms of genetic damage are not seen in the first or second generations, but only later, after several generations have passed.

Among human populations, there is little direct evidence of radiation-induced genetic damage. Several scientific studies have found a significant increase in the incidence of a genetic disease known as Down's syndrome (also called mongolism) following irradiation of the mother, but other studies have not shown a comparable increase. An unusually high incidence of Down's syndrome has also been reported from some geographical regions where the background radiation levels are likewise unusually high. Thus, while there is evidence that radiation causes Down's syndrome, the evidence is not conclusive.

Despite the lack of conclusive studies showing genetic effects in humans, scientists consider it virtually certain that such effects are indeed caused in humans by exposure to atomic radiation, since these effects have been demonstrated in many other species.

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J.5. How else can atomic radiation damage unborn children?

A recent British study (the Gardner Report, published in the Journal of the British Medical Association in February, 1990) shows that the children of men who work in the Sellafield nuclear plant in northern England experience a much higher rate of leukemia than other children. The radiation exposure of the father appears to play an important role. It may be that damage to the sperm before conception causes leukemia in the children born later on -- but no one knows exactly how or why.

Even if the father and the mother conceive a healthy baby, that baby is vulnerable to radiation while it is growing in the mother's womb. Whatever the mother eats can travel through the umbilical chord to the baby and damage it so that it is born with a disease or a deformity. The unborn child can also be affected by penetrating radiation from outside the mother's body. Sometimes when a baby is seriously damaged before birth it is spontaneously aborted or it dies at the time of birth.

Mental retardation due to brain damage is the most likely form of developmental abnormality resulting from exposure to atomic radiation, if the f¤tus is exposed during the critical period when the child's brain is being formed. Radiation-induced mental retardation has been observed and documented in animals as well as humans.

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J.6. Is there a cure for radiation victims?

Some of the damage caused by radiation is healed by the body's own power to heal itself. Rarely is the healing perfect. Medical treatment can relieve some of the side effects of radiation damage and can prolong life through cancer surgery or treatment.

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J.7. Can radioactivity be detected by human senses?

In concentrated form, radium or thorium or polonium can give a person a severe burn. Also, when uranium is exploded in an atomic bomb or "burnt" in a nuclear reactor, many radioactive substances are produced, that give off atomic radiation intense enough to kill a person very quickly with burning pain.

However, at much lower doses, such as those experienced in uranium mining, atomic radiation cannot be detected by any of our human senses. Special instruments are needed. Alpha radiation, the kind associated with radon gas and most of the other uranium decay products, is difficult to detect even with instruments.

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J.8. Are medical and dental x-rays free of risk?

Although x-rays are often useful and sometimes necessary, they do cause damage to living cells, slightly increasing the risk of both cancer in the individual exposed and genetic damage to his or her subsequent offspring. That's why lead aprons or shields are now used to protect the patient's gonads.

As with all forms of atomic radiation, the risk from x-rays is cumulative; it increases with each extra little dose. That's why doctors, nurses and technicians often leave the room or duck behind a wall while a patient is being x-rayed.

Although the risk from one x-ray is small, the public health consequences of routine exposures can be serious because of the large numbers of people exposed to that small extra risk. That's why x-ray machines in shoe stores (letting kids see their toes wriggle) have been disallowed, and mass programs of chest x-rays have also been discontinued.

Twenty-five years ago, Dr. Alice Stewart (a British M.D.) showed that a single diagnostic x-ray to the abdomen of a pregnant woman increased by fifty percent the chance that her child would later develop leukemia. It is no longer acceptable to x-ray unborn babies unless there is a compelling medical reason to do so.

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K.1. What is an "acceptable" level of exposure to atomic radiation?

There is no convincing scientific evidence that there is a safe dose of atomic radiation. The evidence points strongly to the opposite conclusion -- that every dose of atomic radiation administered to a large population, no matter how small it may be, will cause a corresponding increase in the numbers of cancers, genetic defects in offspring and other diseases.

The increase in the incidence of cancers and genetic defects seems to be roughly proportional to the total radiation dose received by the entire population. If the radiation dose is cut in half, the increase in the number of people dying of cancer or having defective children will also be cut in half, but the degree of damage to each affected individual is undiminished. Lowering the dose reduces the frequency but not the severity of the medical consequences. Every regulatory body in the world uses this principle as the basis for regulating radiation exposures.

Since no dose is safe, there is no objective or scientific way to decide what dose is acceptable. It is a social or political choice, not a technical or scientific one. The situation is further complicated when the people who receive the benefits are not the only ones who are taking the risks.

Science can only help us to estimate the risks -- how many people are likely to get cancer, how many children are likely to be born defective, or what other types of illnesses might increase as a result of a given exposure to radiation. To judge whether or not these consequences are acceptable is beyond the scope of science.

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K.2. Who is responsible for regulating radiation exposure in Canada?

The Atomic Energy Control Board (AECB) is responsible for regulating radiation exposure in Canada in cooperation with the Radiological Protection Bureau of the federal Department of Health and Welfare. Since the AECB has little medical or epidemiological expertise, it also depends heavily on research done and recommendations made by bodies outside Canada.

In particular, it relies on the advice of the International Commission on Radiological Protection (ICRP), a self-appointed international advisory body consisting of prominent scientists who work in the field of atomic radiation. Critics have charged that ICRP members are in a conflict-of-interest situation, because their careers are based on jobs which inevitably expose people to man-made radiation.

The AECB sets maximum permissible levels of radiation exposure for atomic workers and for members of the general public. These levels are not regarded by the ICRP as acceptable levels for continuous exposure, but as upper limits beyond which radiation exposure becomes clearly unacceptable. Attempts are made to keep actual exposures to a small fraction of the maximum permissible limits, but there is no guarantee that this will always be the case.

The industry and the regulators claim to follow the ALARA principle, which means keeping radiation exposures "As Low As Reasonably Achievable, social and economic factors being taken into account." But who decides what is reasonable? Critics of the industry claim that current occupational and public exposures are already in many cases unreasonably high, particularly in the light of recent scientific studies published since 1988 which indicate that the risks from low-level radiation are from two to eight times as great as previously thought.

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K.3. What is the basis for setting radiation standards?

In a very real sense, radiation standards are arbitrary. While maximum permissible levels of radiation exposure have been defined for workers and for the general public, these exposures should not be regarded as safe, or even acceptable. The International Commission on Radiological Protection (ICRP) warns that it would be unacceptable for workers or for members of the general public to be exposed continuously to the maximum permissible dose levels.

Radiation standards are for people only, ignoring other species. The assumption that if humans are protected, so are non-humans, is now being seriously questioned.

Two approaches have been used to justify the existing radiation standards. The first involves estimating the risks of death and genetic damage from a given dose of radiation, and comparing these radiation risks with other risks (e.g. deaths from car accidents, hazardous work, fires, earthquakes, spontaneous birth defects, over-eating, etc.) in an effort to make these two kinds of risk more or less comparable. The second approach involves comparing the permissible levels of man-made radiation to the levels of naturally-occurring background radiation.

These approaches have been criticized. The first approach compares risks which people can take steps to avoid with risks of exposures to atomic radiation which are not within the individual's control or power to choose. This approach also assumes an accurate knowledge of the true risks of low-level radiation exposure; but there is growing scientific evidence that these risks have been seriously underestimated for decades. The second approach ignores differences between naturally-occurring radiation and man-made radiation; the latter sometimes involves radioactive substances or biological mechanisms which may not be characteristic of naturally occurring radiation.

Both approaches assume that it is acceptable to add the risks of "technologically enhanced" radiation exposure to all the other risks to which we are already exposed, or to multiply the risks from background radiation by some arbitrary factor.

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K.4. What is "background radiation"?

Some radiation exposure is unavoidable, even in the absence of uranium mining and nuclear technology. This "background radiation" is due to small quantities of radioactive materials in the natural environment -- food, water and air -- as well as penetrating rays from outer space to which we are all exposed.

In some places, background radiation is higher than in other places, depending on the altitude, the nature of the soil, and the type of building materials used. In recent years, it has become clear that the largest and most dangerous single source of exposure to background radiation is in the form of naturally occurring radon gas.

It is considered that many of the cancers and birth defects that spontaneously occur in human populations are caused by our unavoidable exposure to background radiation.

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K.5. Is background radiation increasing?

Because of man's activities, background radiation exposure is gradually increasing as greater quantities of naturally ocurring radioactive materials are being released into the biosphere (for example, through uranium mining).

We have added significantly to the unavoidable radiation exposure of all people on earth because of fallout from nuclear weapons testing and nuclear power plant discharges, particularly in the case of a large-scale accident like Chernobyl.

The medical profession has also added to our average radiation exposure through the use of x-rays. In addition, small quantities of medical and industrial radioisotopes (man-made radioactive substances used for "tracers" or therapeutic purposes) often end up in soil, water or air.

Although the term "background radiation" is not meant to include bomb fallout, reactor discharges, medical exposures or environmental contamination from radioisotopes, it is nevertheless a fact that people all over the world are being exposed to increasing doses of radiation because of these factors.

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K.6. Is radon in homes a problem? how does it get there?

In the U.S., the U.K. and Sweden (but not yet in Canada), the governments have recently urged all citizens to measure the radon in their homes for their own safety.

Radon in homes is produced from tiny amounts of radium found in the soil or in building materials. Radon can also enter homes dissolved in tap water. A certain amount of radon is natural and unavoidable, but nonetheless dangerous. The more radium there is, the greater the problem. Of course, in uranium mines and in uranium tailings the amount of radon is far greater than that in most homes.

In some places, such as Port Hope, Ontario, and Grand Junction, Colorado, elevated radon levels in homes and schools resulted from the use of abandoned uranium tailings or other uranium wastes in construction. In other places, such as Oka, Quebec, and St. Johns, Newfoundland, radium-contaminated materials have been sold to unsuspecting builders, leading to high radon levels in many homes.

A new British medical study (published in The Lancet in April 1990) has found a significant correlation between elevated radon levels in homes and serious illnesses like myeloid leukemia in children and kidney cancer in adults. This study uses published statistics from fifteen countries, including Canada.

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K.7. Are Canadian exposure standards being made more stringent?

In recent years, Canadian authorities have been relaxing exposure standards for atomic radiation rather than tightening them. Within the last decade, the maximum permissible concentration of radium in Canadian drinking water was increased by a factor of nine. The maximum permissible concentration of uranium in water is also being increased. New regulations proposed by the AECB, and not yet passed into law as of September 1990, will increase the maximum permissible intake of many radioactive subtances in the workplace.

Meanwhile, in other countries, the standards are being tightened because of new scientific evidence which indicates that the risks from low level exposure to atomic radiation are considerably higher than was thought just a few years ago. In the U.K., the suggested maximum permissible exposure for atomic workers has been lowered to 40 percent below Canada's current permissible level. In the U.S. and the U.K., the suggested maximum permissible exposures for members of the general public are much lower -- by more than a factor of ten -- than the corresponding figures in Canada.

Canadian regulatory authorities have never held public hearings to decide on radiation standards, despite numerous official recommendations that they do so. They have they never had any representation from the broad Canadian public on their decision-making bodies. It is ironic that radiation standards are now being passed into law in Canada, based on an antiquated report published by the ICRP in 1977, rather than on the best scientific evidence which is currently available.

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