2. What is Radiation?
Radiation is the emission of energy as electromagnetic waves or as
moving subatomic particles, especially high-energy particles that
cause ionization.
Radiation has a wide range of energy that forms the electromagnetic
spectrum. The spectrum has two major divisions: ionizing and non-
ionizing radiation.
3. Ionizing Radiation
Ionization is the process in which a charged portion of a molecule (usually an
electron) is given enough energy to break away from the atom.
Ionizing radiation is so high in energy it can break chemical bonds. When these
bonds are broken, it can charge (or ionize) an atom that interacts with it.
When at a lower energy, it may break off a couple of electrons. At a higher energy,
it can destroy the nucleus of an atom. This means that when ionizing radiation
passes through the tissues of the body, it actually has enough energy to damage
DNA.
Examples: electromagnetic radiation, particulate radiation, medical x-rays,
nuclear radiation (from nuclear explosions, weapons, etc.), industrial gamma rays,
and consumer products (such as TVs or certain lights).
Nuclear explosions contain many sources of ionizing radiation. When nuclear
explosions occur, the radiation (gamma rays, x-rays etc.) superheat the air and
causes it to combust.
There are three main kinds of ionizing radiation:
Alpha particles, which include two protons and two neutrons.
Beta particles, which are essentially electrons.
Gamma rays and x-rays, which are pure energy (photons).
4. Non-Ionizing Radiation
Non-ionizing radiation is low-energy radiation that doesn't have enough
energy to ionize atoms or molecules.
We are exposed to non-ionizing radiation everyday.
It is located at the low end of the electromagnetic spectrum.
Examples: power lines, microwaves through telecommunication and heating
food, radio waves from broadcasting, infrared radiation from lamps,
ultraviolet radiation, visible radiation, cell phones, and lasers.
Some forms of non-ionizing radiation can damage tissues if you are exposed
too much to it (such as sitting in the sun for too long, and getting sunburn).
Overexposure to non-ionizing radiation can cause health issues, such as
damaged skin, burns, cancer, cataracts on the eye, etc.
5. How Radiation is Measured
The exposure to radiation is represented by the following equation:
Exposure = Dosage x Q
The amount of radiation
absorbed over time. It is
measured in Rads, Grays (the
SI unit) (1 Gray = 1 rad), or
ergs (1 Rad = 100 ergs).
The amount of tissue
damage caused by
radiation This varies
between different types
of radiation:
For x-rays and gamma
rays, Q=1.
For alpha particles, Q
= 15-20 (depending on
amount of particles)
For neutron rays,
Q=10.
Compares the radiation
exposure to the amount of
tissue damage (Q). It is
measured in rems. It could be
measured in seiverts (Sv),
but it is mostly measured in
rems. 1 SV = 100 rems
6. Radiation Exposure on the Human Body
Ionizing radiation, particularly nuclear radiation, can produce fatal
consequences if the human body is exposed to large amounts of radiation.
Something is “irradiated” when radiation is exposed to it, and could
potentially be damaged by it.
Ionizing radiation may act on cellular parts or simply just water inside human
cells. Radiation can react with water, creating water derived radicals, which
if it reacts with nearby molecules like cell parts, it will result in the breaking
of chemical bonds of these molecules through oxidation.
The most major effect of radiation in cells is the breaking of DNA molecules. As mentioned
above, radiation may break the double-stranded DNA, and if the cell tries to repair that DNA, it
will often “disrepair” itself and create errors in new DNA. This results in cell death.
Radiation exposure to the body most often occurs in chemotherapy in cancer patients, so
radiation exposure is small and only kills targeted cells. But in situations like nuclear accidents,
radiation can kill cells all over the body.
All radiation exposed to the body increases a person’s risk for cancer. Although most radiation
we are exposed to is non-ionizing, small tasks like talking on your cell phone for long periods of
time for a long time can caused pain in the ear because of the radiation that modern cell
phones emit.
8. Sample Problem
During the test run of an atomic bomb in the United States, the overall dosage of
radiation given off by the bomb was estimated to be 14.1 seiverts. The bomb
produced mainly neutron rays to be emitted. What was the overall radiation
exposure that people would have experienced if the bomb was really used in a
populated area? Would people survive?
1. Convert seiverts to rems
14.1 seiverts x
100 Rems
1 seivert
= 1410 rems
2. Q = 10, since neutron rays produce about 10 units of tissue damage
3. Exposure = 1410 rems x 10.
4. Exposure = 14,100 rads.
14,100 rads causes instant death, so people wouldn’t be able to
survive.
