P A R T
O N E
Nuclear Radiation and its Biological Effects
The future of humankind is present today within the bodies of living
people, animals and plants -- the whole seedbearing biosphere. This
living biosystem which we take so much for granted has evolved
slowly into a relatively stable dynamic equilibrium, with predictable
interactions between plants and animals, between microscopic and
macroscopic life, between environmental pollutants and human
health. Changes in the environment disturb this balance in two
ways: first, by altering the carefully evolved seed by randomly
damaging it, and second, by altering the habitat, i.e. food, climate
or environment, to which the seed and/or organism has been
adapted, making life for future generations more difficult or even
examples of maladaptation in nature and resulting
species extinction abound, our focus here is on human seed, the
sperm and ovum, and the effect on it and on the human habitat
resulting from increasing ionising radiation in the environment.
increased use of radioactive materials, which is a direct
outgrowth of the current military and energy policies of the
developed world, provides an opportunity for gauging what priority
these countries give to the health and well-being of individual
citizens, and for gauging governments' understanding of the tension
between individual and national survival. The first indicator of
underlying national priorities is the precision or lack of precision
with which health effects are predicted, and the thoroughness with
which an audit is taken and the predictions checked against
reality. The audit findings should be reported to the person or people
affected, and their participation sought in formulating changes in
policy to remedy any unanticipated problems. The individual's
sense of self-preservation and personal benefit, in such an ideal system,
would give realistic feedback to governments on the acceptability of national
policy. The combined experiences of governing and governed would forge a
national consensus on future directions.
- ABCC Atomic Bomb Casualty
Commission. Now called Radiation Effects Research Foundation (RERF)
- Alpha particle an electrically
charged ( + ) particle emitted from the nucleus of some
radioactive chemicals, cf. plutonium. It contains 2 protons
and 2 neutrons, and is the largest of the atomic particles
emitted by radioactive chemicals. It can cause ionisation.
- Beta particle an electrically charged
( - ) particle emitted from some radioactive chemicals. It has
the mass of an electron. Krypton 85, emitted from nuclear power
plants, is a strong beta emitter. Beta particles can cause
- Curie a measure of radioactivity.
One curie equals 3.7 x 10^10 nuclear transformations per
second. Ci is the symbol used.
- Microcurie: one-millionth of a curie.
(3.7 x 10^4 disintegrations per second) mCi is the symbol used.
- Picocurie: one-millionth of a microcurie.
(3.7 x 10^-2 disintegrations per second) pCi is the symbol used.
- Dose energy imparted to matter by
nuclear transformations (radioactivity).
Rad = 100 ergs per gram.
1 GRAY = 100 rad = 10,000 ergs per gram.
- Rem = rads x Q
where Q is a quality factor
which attempts to convert rads from different types of
radioactivity into a common scale of biological damage.
1 SIEVERT = 100 rad.
- Gamma ray short wave-length
electromagnetic radiation released by some nuclear
transformations. It is similar to X-ray and will penetrate
through the human body. Iodine 131 emits gamma rays.
Both gamma and X-rays cause ionisation.
- Half-life, biological
time required for the body to eliminate
one-half of an administered quantity of a radioactive chemical.
- Half-life, physical
time required for half of a quantity of
radioactive material to undergo a nuclear transformation. The
chemical resulting from the transformation may be either
radioactive or non-radioactive.
- Ionisation sufficient
energy is deposited in a neutral molecule to
displace an electron, thus replacing the neutral molecule with
positive and negative ions.
- Radiation the emission and
propagation of energy through space or
tissue in the form of waves. It usually refers to electromagnetic
radiation, classified by its frequency: radio, infrared, visible,
ultraviolet, X-ray, gamma ray and cosmic rays.
- Natural background radiation --
emissions from radioactive chemicals which
are not man-made. These chemicals include uranium, radon,
potassium and other trace elements. They are made more
hazardous through human activities such as mining and milling,
since this makes them more available for uptake in food, air and
- Background radiation --
includes emissions from
radioactive chemicals which occur naturally and those which result
from the nuclear fission process. The meaning of this term is
vague. In a licensing process it includes radiation from all sources other
than the particular nuclear facility being licensed, even if the
source includes a second nuclear facility located on the same site
(US regulations). Radioactive chemicals released from a nuclear
power plant are called `background' after one year.