Irradiated foods are foods that have been exposed
to ionizing radiation. Ions are electrically charged
particles, and ionizing radiation is radiation that produces
these charged particles. Nonionizing radiation is
produced by microwaves, television and radio waves,
and visible light. Ionizing radiation is higher in power
than these types of radiation, although it is in the same
spectrum. The kinds of ionizing radiation used for
food irradiation include gamma rays, beams of highenergy
electrons, and x rays.
When foods are irradiated, they are exposed to the
source of the ionizing radiation for a short time. This
radiation produces short-lived compounds that damage
the deoxyribonucleic acid (DNA) of living organisms,
such as bacteria that are in the food. Because
DNA makes up the genes that contain the instructions
that tell an organismhow to grow and reproduce, once
the DNA is damaged the organism cannot do this
correctly and will die.
The amount of radiation required to irradiate
foods depends on the type and thickness of the food
product and the type of organismthat are present. The
larger the DNA of the organism, generally the less
radiation is required to irradiate it. Insects and parasite
have the larger DNA and require the lowest levels
of radiation, while bacteria generally require slightly
more, and viruses have very small amounts of DNA
and require very high levels of radiation. Most parasites,
insects, and bacteria can be eliminated at levels of radiation approved for commercial use, but many
viruses cannot.
Irradiating foods does not make the foods radioactive
in any way. Irradiation done using beams of
high-energy electrons or X-rays do not even use any
radioactive material. Irradiation done using gamma
rays involves exposure of the food to a radioactive
substance, usually cobalt 60 or cesium 137, for a short
period. The radioactivity of this substance is not in any
way transferred to the food that is exposed to it.
Precautions
Irradiation is not a substitute for safe food handling
practices. Although irradiation kills or disables
many pathogenic organisms, these organisms can be
reintroduced to the foods if cross contamination
occurs. In addition, not every pathogen is completely
destroyed by irradiation, and leaving foods such as
raw meat out at room temperature can allow these
pathogens to reproduce to significant levels. Irradiation
should be viewed as an extra step to help ensure
that the food supply is safe, not as a replacement for
food safety practices that are already in place.
Interactions
Irradiated foods are not expected to interact with
any other foods, medicines, or products.
Complications
There are no complications expected from consuming
irradiated foods. Some concerned groups have
expressed fears that the long-term effects of eating
irradiated food are unknown. However, many different
scientific studies have examined the effects on both
animals and humans of consuming irradiated foods.
There has not been any evidence that irradiated foods
are harmful in either the short or the long term.
One
study even examined many generations of animals fed
irradiated foods and found no harmful effects. Irradiating
food is accepted as a safe practice and is
endorsed by many organizations including the World
Health Organization, the Centers for Disease Control,
the United States Food and Drug Administration, and
the American Medical Association.
Parental concerns
Some parents may have concerns that the vitamin
and nutrient content of irradiated foods may be
reduced compared to the content of the same foods
that have not been irradiated. For most vitamins, minerals,
and nutrients this is not the case.
Studies have
shown that the levels of most vitamins in irradiated
foods are not significantly different from the levels in
foods that have not been irradiated. Some vitamins
however, such as thiamine (vitamin B1), have been
found to be sensitive to irradiation. The extent to
which such vitamins are destroyed however, depends
greatly on type of food being irradiated. Thiamine was
found to be decreased by 50% in a water solution that
was exposed to radiation, but only decreased by 5% in
a dried egg exposed to the same level of radiation.
Many vitamins, like thiamine, that are sensitive to
irradiation are as sensitive, or even more sensitive, to
heat, and are broken down at least as much by the
process of canning or heat treatments. Therefore,
although levels of some vitamins may be decreased in
irradiated foods compared to fresh foods, the levels of
these vitamins may be higher in irradiated foods than
in comparable canned or otherwise sterilized foods.
