The Rural Voice, 1988-10, Page 24FOOD
IRRADIATION
Some say it's "a silent
nuclear war." Others say it's "a
real opportunity for Canada."
Food irradiation, in short, is a
controversial agri-food issue.
And as October is the month of
Agri -Food Week, writer Ian
Wylie-Toal has researched the
subject of food irradiation from
both sides.
The black symbol shown
right is used internationally to
mark irradiated food.
F
ood processing is not
normally a topic associated
with controversy. It is hard,
for example, to imagine tempers
flaring during a discussion of canning.
The technical points of freezing are
not normally regarded as ammunition
to be thrown back and forth between
two radically opposed groups. Drying
and salting rarely prompt outraged
letters to the editor.
Food irradiation is different.
Discussions of this issue are often
marked by animosity and hot tempers.
Newspaper articles and letters from
the past year or so reveal the split:
one side describes food irradiation as
"subtle and insidious," a "scam," a
"threat," and "a silent nuclear war."
The other calls it "safe," "a real
opportunity for Canada," a process
that could "make our food safer and
cleaner" or "reduce starvation." It is
difficult to believe that all of these
descriptions fit the same process.
So what is food irradiation, and
why does it provoke such different
responses? Answering the "what" is
relatively simple; the "why" is much
more difficult and requires a bit of
explanation. As with any contro-
PROGRESS or
POISON
versial topic, more than facts are
involved in shaping opinion: differing
world views, trust in institutions, and
belief in science all have their place in
the discussion.
The aim of food irradiation is the
same as that of all food processing, to
preserve food in a state fit for human
consumption by getting rid of bacteria,
fungi, insects, and parasites. Stopping
normal plant processes such as sprout-
ing and ripening are also goals. Con-
ventional methods use drying, chill-
ing, heat, or chemical additives. Food
irradiation uses ionizing radiation.
There are several types of food
irradiators, but the most common one
works by exposing food to a cobalt -
60 source. Cobalt -60 is an unstable
form of cobalt -59 and is produced de-
liberately during the normal workings
of a CANDU reactor. Cobalt -60 is
not, however, a nuclear waste product,
as is the caesium 137 used in many
U.S. irradiators.
As cobalt -60 decays to a lower
energy state (forming nickel), it emits
gamma rays — high-energy, short-
wave radiation which penetrates food.
As the rays travel through the food
they lose energy to large molecules by
ionizing them (removing or adding an
electron), making these molecules
unstable so that they break, decay, and
react with others to form stable radio -
lytic products (RPs).
If the food is a plant, this process
disrupts its normal internal workings,
halting sprouting and ripening. The
DNA of organisms living on or in the
food is especially susceptible to ioni-
zation because this genetic disruption
kills or sterilizes them. If the food is
properly sealed before irradiation, it
can be stored indefinitely at room
temperature without rotting.
A commercial irradiator consists of
a cobalt -60 source which is stored in
deionized water when not in use. A
concrete wall surrounds it to absorb
any escaped radiation. Food to be
irradiated is loaded onto a conveyor
system which takes it into the build-
ing, around the exposed radiation
source, and back out again.
Irradiation is cleared for use in
approximately 32 countries for 30
foods, but only about a third of these
countries allow the food to be sold in
stores. The others allow its use only
for medical, agricultural, and scientific
purposes.
22 THE RURAL VOICE