> > > radiolytic products mentioned in the article are normally found in
> > > foods.
> That seems vague. In which foods (cooked?)....at what levels?
> According to this logic it's therefore acceptable to include these
> products in all foods which are irradiated.
When a particle or photon of sufficiently high energy rips through
water, it knocks electrons off the water molecules, producing OH
radicals. These are so reactive that they chemically rip up anything
they touch and are gone in a few milliseconds (probably longer if the
food is dry). DNA is nicked, and this kills or weakens bacteria. Free
radical chain reactions are initiated in lipids and proteins, and gives
rise to radiolytic products. But these reactions are not unique to
Almost nothing is more violent in nature than the chemical assault
launched by white blood cells, for example. This involves hypochlorite,
nitric oxide, and free radicals. Ordinary respiration involves passing
electrons among proteins, the handoffs sometimes go wrong, and free
radicals are formed in your body. We are loaded with systems that
detoxify these things. The oxygen-rich environment we live in is
chemically violent. Molecular oxygen has enough affinity for electrons,
that it can directly initiate free radical chain reactions in foods.
Lots of nasty chemicals are formed, and we call it rancidity.
With all these things, dose is the critical issue.
> Those unique to the irradiation process are known as "unique
> radiolytic products" (URPs).
I see no mention of dose or toxicity.
> Some radiolytic products, such as formaldehyde, benzene, formic acid,
> and quinones are harmful to human health.
The paper implies that these are the URP's, but they are not. And
again, no mention is made of the levels found in food.
> Benzene, for example, is a
> known carcinogen. In one experiment, seven times more benzene was
> in cooked, irradiated beef than in cooked, non-irradiated beef.
What about the other experiments? And were the levels dangerous?
> URPs are completely new chemicals that have not even been identified,
> let alone tested for toxicity.
All the foods we eat are loaded with uncharacterized stuff at low
> In addition, irradiation destroys essential vitamins and minerals,
> including vitamin A, thiamine, B2, B3, B6, B12, folic acid, C, E, and
> amino acid and essential polyunsaturated fatty acid content may also
> affected. A 20 to 80 percent loss of any of these is not uncommon.
Is this important in a normal diet? What fraction of these in our diet
do we get from meat anyway?
> Are you suggesting that even the unique radiolytic products (URPs)
> "are normally found in foods." ?
This is circular reasoning. Anyway, I don't know enough to pass any
judgement on URP's The paper you quoted didn't shed any light. I did a
literature search to find out more. Let me know if you want a copy and
I'll send it directly.
I have attached the abstract of a paper that I believe puts the
toxicology of radiolytic products in the proper perspective, although it
really deals more with pesticide issues. Let me know if you want a
copy, I'll fax it.
TI Rodent Carcinogens:Setting Priorities
KE pesticide mania paranoia toxicology dose-response extrapolation
AB The human diet contains an enormous background of natural chemicals,
such as plant pesticides and the products of cooking, that have not
been a focus of carcinogenicity testing. A broadened perspective
that includes these natural chemicals is necessary. A comparison of
possible hazards for 80 daily exposures to rodent carcinogens from a
variety of sources is presented, using an index(HERP) that relates
human exposure to carcinogenic potency in rodents. A simialar
ordering would be ecpected with the use of standard risk assessment
methodology for the same human exposure values. Results indicate
that, when viewed against the large background of naturally
occurring carcinogens in typical portions of common foods, the
residues of synthetic pesticides or environmental pollutants rank
low. A similar results is obtained in a seperate comparison of 32
average daily exposures to natural pesticides and synthetic
pesticide residues in the diet. Although the findings do not
indicate that these natural dietry carcinogens are important in
human cancer,, they cast doubt on the relative importance for human
cancer of low-dose exposures to synthetic chemicals.
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