Authors:
Dr. Cathy Vakil M.D., C.C.F.P., F.C.F.P.
Dr. Linda Harvey B.Sc., M.Sc., M.D.
May 2009
The authors would like to thank Gordon Edwards, David Martin and Terry Mauer for their help in preparing this paper.
EXECUTIVE SUMMARY5
Ever since the discovery of radioactivity at the turn of the last century, it has been recognized that ionizing radiation has a deleterious impact on human health. Radiation damage can affect any part of the cell and can interfere with many cellular processes. Most importantly, damage to the genetic material of the cell can lead to cancer, birth defects and hereditary illness. It is generally accepted by the scientific community that there is no safe level of radiation exposure, and that any amount of
exposure to ionizing radiation is harmful.
Standards of acceptable exposure in Canada and elsewhere have been reduced many times over past decades, as evidence has mounted of more deleterious health effects. Effects of chronic low-level exposures are poorly understood, especially in children. All stages of the nuclear fuel chain have their associated toxicity. There is also the continuing risk of accidents or meltdowns, which could release massive amounts of radioactivity, such as occurred at Three Mile Island and Chernobyl.
Much of the long-lived radioactive contamination we are spreading into our environment now is essentially permanent and irreversible.
This paper will examine the health risks associated with the nuclear power industry at all stages - from uranium mining, to the fission process in reactors, to radioactive waste, and will comment on the risk of nuclear war, which we regard as the ultimate public health issue.
Uranium mining contaminates air, water and soil. Crushing tons of radioactive rock produces dust, and leaves behind fine radioactive particles subject to wind and water erosion. Radon gas, a potent lung carcinogen, is released continuously from the tailings in perpetuity. Drilling and blasting disrupt and contaminate local aquifers. Water used to control dust and create slurries for uranium extraction becomes contaminated. Tailings containments can leak, leach or fail, releasing radioactive material into local waterways. Various organisms can transport radioactive material away from contaminated sites. These sites remain radioactive for many thousands of years, and will be unsafe to use for most human purposes for that long, as well as being a source of continuing contamination for surrounding populations.
Uranium refining and enriching facilities release radioactive contamination which can impinge on nearby populations. These processes also necessitate transporting many tons of radioactive material by rail or truck. This carries with it the risk of accidents or spills, with further risk of air, water and soil contamination.6
RADIATION AND HEALTH OVERVIEW
There are three types of atomic radiation of principal concern to human health and safety in regard to uranium mining and nuclear power generation. These are alpha, beta and gamma radiation.
Alpha and beta radiation involve high-speed electrically charged particles with mass, and gamma radiation involves electromagnetic energy. Neutron radiation is a fourth type of atomic radiation, involving particles with mass but no charge. All of these are capable of displacing electrons from atoms and molecules, and are referred to as ionizing radiation.
Alpha particles, composed of 2 protons and 2 neutrons, and being bulky, are the most biologically destructive of the three. They have been found to be up to 20 times more damaging to intracellular structures than gamma rays.
They were once considered to be safe by the nuclear industry because they do not normally penetrate skin. Ingested or inhaled, however, and positioned within living tissue, they can discharge their alpha particles directly into the structures of the cell, damaging the cell’s contents, including its DNA.
Radon, the second leading cause of lung cancer after smoking, is an alpha emitter, as are plutonium 239, uranium 238 and its daughters, uranium 234, thorium 230, radium and polonium.
Some DNA damage is reparable by the cell, but alpha particles are more likely than other forms of radiation to cause double-strand DNA breaks which are not readily repaired. Attempts at repair can lead to deletions, inversions, acentric fragments and cross-linking, as repair enzymes try to work with missing and scrambled pieces. It is well known that damaged
DNA can trigger many diseases in humans such as cancer (13), 14 teratogenic effects including mental retardation and birth defects (14), chromosomal abnormalities (15) and inheritable disease (7,13). Beta particles are high-speed electrons, with a small amount of mass and considerable energy. Their effects on biological tissue are somewhat intermediate between alpha and gamma radiation, although closer to those of gamma radiation.
BACKGROUND RADIATION
The scientific community generally agrees that there are no “safe” levels of exposure to ionizing radiation, and that any exposure carries the risk of harm (10).
“Acceptable” levels are based on “acceptable harm”. Natural background levels in most parts of the world are considered to be in the order of 2.4 mSv/yr, with about 1.0 mSv being gamma radiation, mostly from cosmic rays, and the remainder being alpha radiation, largely from radioactive radon gas.
This varies somewhat with elevation and other geographic features.
Background levels of radiation are thought to contribute to background rates of cancers and genetic defects, and the aging process.
According to nuclear regulatory agencies, an acceptable exposure for the public is currently an additional 1.0 mSv/yr above background. It must be borne in mind that any exposure created by human sources, such as nuclear weapons testing fallout or emissions resulting from nuclear reactor accidents, will be added to background exposures.
15
Nuclear industry workers are allowed to receive 20 mSv/yr averaged over 5 years. Such an exposure, according to ICRP 60 guidelines (17) would be expected to generate 3.2 excess cases of fatal cancer per 100 workers over a 40 year career. This is in contrast to other industrial toxicological situations in which 1/10,000 to 1/million fatalities are considered acceptable (18).
Read more:
http://www.nben.ca/environews/articles/archives/Human%20Health%20Implications%20of%20Uranium%20Mining%20and%20Nuclear%20Power%20Generation_2009__1_.pdf
