The irradiation
of foods and drinks with a view to ensure their preservation has developed
discretely over the years.
But this process provokes
chemical changes, known or unknown, in the
foods treated and in their packaging which, often, alter the quality of
taste of the foods, and in the long term sometimes present a risk to health.
In general the public is poorly or badly
informed about the conservation of foods by irradiation, and all sorts
of confusion arise: many inaccurate remarks have been heard on this subject,
the agri-food professionals have a good game presenting the detractors
of this process as ignorant alarmists.
Many different
sorts of irradiation exist according to the nature of the radiation used
and their power, with highly variable results,
changing also according to the nature of the foods treated. This
diversity, with some bad faith, allows the denial of all the dangers of
irradiation; they often say that this process
does not induce artificial radiation in the treated products, because the
energy in the irradiated particles is insufficient for this....
This is true in the
majority of cases, but absolutely not in all, all the more so when experiments
are concentrated on physical studies when everyone knows that radioactivity
also has chemical effects (1)...
A series of graduated effects
- Radiation at the lowest doses prevents,
by stopping cellular division,
the germination of cereal grains, but above all of tubers (potatoes do
not wither because of germination; the same for bulbs - onions, garlic,
shallots...).
This permits, in a dry atmosphere, prolonged
storage (in packaging pierced with ventilation
holes) without recourse to refrigeration.
- Radiation at distinctly higher levels
attacks insects by making them sterile,
them or their immediate descendants.
- Then, at a higher level, insects cannot
moult, to grow, and if it is still stronger
they are killed.
- Finally, intense radiation at high power
destroys all forms of life.
If the packaging is watertight, the total absence of germs makes these
foods into canned foods which have not been cooked, or the equivalent frozen
products, but which keep at normal temperatures: process applicable to
meat and fish.
Potential dangers
Irradiation is useful commercially in large
scale food distribution, since it allows much
longer preservation of products presented as fresh, and not frozen or tinned.
But living matter - and sometimes even minerals - is often very sensitive
to radiation, and the chemical reactions thus
induced are impossible to foresee in systems as complex as biological organisms,
even when dead. We therefore content
ourselves with tests to determine the immediate toxicity of irradiated
foods. But no retreat, nor enquiries into the long term. The
action that should be taken is, in effect, to study over the years numerous
foods, treated by different methods.
For the rest, we can already say that this
treatment strongly affects the taste of certain foods:
we have already abandoned it for dairy products. It is the best indicator
of chemical changes of proteins, unknown, which could well, in some cases,
create substances which are carcinogenic in
the long term, or capable of attacking certain
organs such as the liver or the brain.
But other risks exist
In the case of moderate irradiation, the
organisms (insects, fungi, bacteria) undergo a modification
to their genetic code. For most of the
time, this profound mutation of structure and physiology leads to death,
but other times, rarer, it can render the organism more aggressive, better
adapted to the function of producing poisons.
When this happens to organisms which multiply
themselves very rapidly, such as bacteria, their power of mutation is considerably
increased, in short a risk appears of unknown
infections, dangerous and difficult to treat.
To what is the emergence of salmonella
and other bacterial illnesses due? Without prejudice, of course,
the effects of chemical pollution and the abuse of antibiotics.
The chemical effects of irradiation, even
weak, are thus incontestable and imperfectly controlled.
There remains the nuclear effects - even
weak - , linked to the radioactivity of the sources used. But
there is not a threshold limit: the probability of inducing higher radiation
with the particles used. And an increase in the radiation absorbed,
even of the order found in nature, leads to additional risks to health
(cancer among others).
But the consumer is not informed of the
techniques used or the implicit energy.
And mineral water?
Treatment by ultraviolet destroys the bacteria
which could have stayed in the water or the packaging, by modifying in
a radical manner their general chemistry.
In view of the weakness of the radiation
used and the short duration of exposure (a few seconds) the
water is not subject to any chemical modification to its simple formula,
and even less an induction of radiation.
This process works because of the transparency of water and the low density
of bacteria involved. To have healthy water it must be agitated
and aerated before being drunk, because water
regenerates itself when it is not polluted by chemicals.
However mineral waters are most often treated
in plastic containers, sensitive to
ultraviolet
which partially decomposes them and allows them to
pollute their contents, at very weak doses,
which, uncontrolled, can produce perverse effects.
Ionising radiation
The radiation used to treat foods and drinks
are at best ultraviolet
rays, already relatively strong; next comes X-rays
classed, according to their power “X soft”, “X medium” and “X strong” and
lastly gamma rays, the most dangerous,
because their considerable energy engenders very many chemical reactions,
and also because they are capable of splitting the nuclei of atoms, which
cause mutations (change of chemical element),
and above all an artificial radioactivity.
The most economic way to produce gamma
rays is to use radioactive substances, by-products
of the spent fuel of nuclear power stations.
The chemical effects of this radiation results
from its ionising character. Sufficiently powerful to displace or
even tear out electrons from nucleus, it disturbs the chemical links between
atoms, basis of the substances which make up living beings.
From then on certain broken/modified molecules
form new products which, in their turn, can react with others to produce
new substances; an unpredictable chemistry
when it acts on animal or vegetable matter which is composed of very complex
and varied molecules, notably the proteins.
As a result, as well as a possible alteration
of the taste of foods, the birth of toxic
substances, may be in the long term: when are we going to notice them?
These phenomena are produced even
with radioactive particles of modest power:
ultraviolet, the weakest, causes tanning by stimulating the formation of
melanin, and changes certain substances into vitamin D.
Even visible light, with even less energy,
can produce chemical ionisation; it acts on chlorophyll.
All this shows well that irradiation, even
with little power, can have beneficial effects but also, in other cases,
ill-fated consequences, when it is applied
in circumstances that living nature doesn’t know how to adapt to for several
years.
Irradiation and DNA
Living cells, man, animal, vegetable, bacteria,
virus contain nucleotides (DNA: deoxyribonucleic acid and RNA: ribonucleic
acid). These molecular chains, billions of atoms long, contain the
plan which assures the composition, function
and development of the living being which
contains them.
A fundamental mechanism, “duplication”,
of the nucleotides allows them to make copies of themselves, destined to
control the growth and physiological functioning of multiple descendants.
But these nucleotides are sufficiently
sensitive to ionising radiation which locally
and randomly modifies the structure of a molecular chain, and sometimes
cuts them. But the system of self repair
of cells is sometimes incapable of absorbing these “malfunctions”,
can increase the effects of the sort that genetic code of a living cell
damaged like this suffers prejudice varying with the dose and above all
the power of the radiation received, which implies a more or less profound
reshuffle of the nucleotides.
In the mildest cases, growth
or development of the living being is found to be affected or stopped.
A stronger doses, transformations (moults,
change from larval form to adult) are prevented
or work badly.
Stronger radiation affects reproduction:
non viable descendants, or even presenting
monstrosities or functional anomalies which
prevent long life and reproduction. With even stronger doses the
exposed organisms becomes sterile,
and their colony can then develop inherited faults...
But the agro-industrial users of ionising
radiation are hardly concerned, preoccupied by the essence, merely the
type of chemical modification which serves
their interests....
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