There
are many different kinds of radiation: even sound waves are a form of very slow
low energy radiation. Ionizing radiation is a particular class of its own; it has enough energy to break up molecules. It ionizes them,
turning them into negatively and positively charged pieces of molecules (called ions).
There
are several types of ionizing radiation: alpha radiation – slow-moving fat
positively charged particles, beta radiation – faster moving negatively charged particles
and gamma radiation – pulses of energy. X-radiation is very similar to gamma
radiation but is machine-made. Neutron radiation occurs naturally only where there is
uranium; only uranium spontaneously exudes neutrons.
No one
disagrees that ionizing radiation is not good for living things. Breaking up molecules whether enzymes, structural proteins or genetic material requires repair - and biological repair may not always be accurate. There is a largely discredited belief that a little bit of ionizing radiation might be good for biological
processes. This myth is largely propagated by supporters of the nuclear industry who seem
continually to try to ease restrictions on industrial and environmental
exposure. Most physicians believe in the precautionary principle; applied in
this instance, less is best.
The
largest proportion of an individual’s lifetime exposure, is from medical or
clinical investigations. This exposure a person can, within some limits,
control. Amounts
of exposure to radiation from the sun, and that from flying at high altitudes
is also largely under our personal control.
Background radiation is largely not under our control. Background
radiation is around 3.1 mSv/yr on large areas of the Canadian Shield and in
parts of the Rockies; the prairies are the lowest at around 2.1
mSv/yr. Winds from certain directions might bring higher levels of radiation. A location in India with a background radiation level of close to 5.0 mSv/yr has a definite increase in offspring with Down’s syndrome. There
have been unusual anomalies documented in high numbers by physicians in the
Ukraine near Chernobyl, amongst the Marshalleise Islanders, in the TRIANGLE in
Kazackstan, and in the South of Iraq (exposed to excessive amounts of uranium-238).
Uranium
is really the start of the nuclear industrial chain since its unique properties
made possible both the nuclear bomb and electricity from nuclear power. Its
importance led to prospecting and mining, milling, transporting, refining, and enriching and
thence to the end uses – bombs and nuclear power plants.
In nature,
uranium appears as a black rock. The Dene people had traditions which told them to
avoid the black rock. It is radioactive and contains traces of the entire
uranium decay chain:
(Please note that the first bismuth in the chain should be bismuth-214 instead of bismuth-210)
Radioactive
elements are continually giving off energy and as they release energy they
change into another element. As this figure shows, uranium has at least
fourteen decay steps between it and the stable, non-radioactive lead-208 at the
end.
When uranium-238 decays to thorium-234, it gives off an
alpha particle. The fat alpha particle can’t get through skin so for a long time it was not considered to be harmful. Inhaled or ingested, however, it is twenty times more
destructive than any other radioactive emission.
Thorium-234,
however, decays by beta particle emission. Whenever a beta particle is emitted,
the atomic number goes up by one, illustrated by the positioning of the
elements in the chain, and the atom becomes a new element. The new element in this decay step, protactinium-234, also decays by beta
emission and becomes uranium-234.
The
next series is the “alpha decay series” – the mass number going down by four
with each decay step. Uranium-234 becomes thorium-230 with the release of an
alpha particle and similarly, thorium-230 becomes radium-226.
Radium-226
is the first of the very energetically radioactive elements in the chain. It was discovered by Madame Curie in 1898. Because
it was new and exciting and glowed in the dark, it was marketed as a cure-all and
thousands of people drank radium water “for their health”. It was responsible
for countless deaths because it is a bone-seeker, lodging in bones and causing cancers such as leukemias and osteosarcomas.
With a
half-life of 1600 years, radium-226 becomes radon-222 which is a gas. In
nature, the gas remains captured in rock for its short decay half life of three and a
half days. In mine tailings, released
from rock, it drifts into the atmosphere downwind as far as several
thousand kilometers while it gradually becomes polonium-218 and settles onto plants
and animals. Polonium is toxic to humans – like arsenic only much more so – an
amount of polonium-210 no larger than the head of a pin killed the Russian spy,
Litveninko.
Additionally,
every decay step releases gamma radiation as well, lead-214 and bismuth-214
being the most biologically destructive.
Even
prospecting can have an environmental impact. A group of people in Nova Scotia
had their water supply affected when a driller went through their aquifer. By mining uranium the surface radioactivity is
affected forever. Where all of the elements in the uranium decay chain
quietly went about their business of decaying in balanced synchronicity bound in granite, they are now a soup of radioactive elements that can be leached into water systems or even affect one
another. They are no longer safely separated by inert granite.
