Detecting ionizing radiation does not mean that a disaster
has or will occur. Detecting radiation
is generally a good thing if the radiation is expected, intended or
natural. We and all living things on earth
are naturally radioactive. This is due
primarily to our requirement to have a healthy level of potassium and carbon in
our bodies (and these are both naturally radioactive).
It is not difficult to measure small fractions of the
radiation coming from natural sources.
This includes alpha, beta and gamma radiation coming from radon in the
air and all of its decay products. Similarly, the radium in the earth from the
natural decay of uranium and thorium is also fairly easily measured. Radiation dose rates from natural background
are readily measured with the right equipment.
Dose rates above these values are again not difficult to quantify for
gamma and x-ray radiation.
The average radiation dose a US citizen receives from
breathing unfiltered air from the environment is over 200 mrem in a year due to
natural radon. This is more than twice
the limit an adult citizen is allowed to receive if they were to be working at
a nuclear facility. A radiation worker
can receive up to 5000 mrem in a year legally but they have special training to
enable them to keep their doses as low as possible and how to be informed and
monitor their doses to support this function.
Typical radiation workers in the nuclear industry receive around 100
mrem per year from occupational exposure.
Typical annual doses to airline pilots and stewardess are also in this
range if they do enough transcontinental flights as the cosmic radiation
increases substantially with altitude and flight duration.
Legal exposure levels to members of the public who are not
working on a nuclear facility range from 10 mrem to 25 mrem per year depending
on the regulatory body having jurisdiction.
This is approximately the same level of exposure a person receives from
the natural potassium in their body required to stay healthy. Potassium is both essential for life and a
high energy beta and gamma emitter.
Scientific organizations specializing in this field report
that the minimum radiation dose required to see any medical effects is around
10,000 mrem. This only holds if very
large numbers of people in a community receive this or higher doses to be able
to see a small but statistically significant increase in the probability of
cancer. Legally an emergency responder
can receive doses in this range if it is required in the process of saving
lives and they are fully informed of the health risks associated with these
efforts.
In order to see any medical effects for a single person from
a radiation exposure requires receiving a dose of around 100,000 mrem. At levels this high, male fertility will
start to decrease and the skin will react with reddening like a sunburn. Doses that are considered comparable to
chemical exposures which are immediately dangerous to life and health are
greater than 400,000 mrem.
All of these effects are typically attributable to receiving
the dose over a short period of time.
Many in the field believe the body's healing ability can easily repair
from radiation exposures if they are in the range of environmental levels due
to the natural healing process. This is
consistent with the scientific results
Medical exposures can range as high as 1,000 mrem in some
rare cases but on average, the annual dose citizens receive from medical
services is similar to the dose we all receive from natural sources.
