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BLOG: August 2008

More irradiated foods from the FDA

Before the end of this month, irradiated spinach and iceberg lettuce will join the list of irradiated foods allowed by the FDA to be marketed to the general population. Is it good or bad?

Proponents of food irradiation focus on better safety from outbreaks of infectious foodborne diseases, and longer shelf life. And the opponents are concerned by possible health risks due to consumption of irradiated foods. Let's take a bit closer look at these two opposing aspects of food irradiation.

 What is the added degree of protection from irradiating foods? The US National Center for Policy Analysis estimate is that irradiating half of the high-risk foods would reduce food-borne illnesses by 900,000 and deaths by 352, annually. According to their figures, it would amount to about 6.5% reduction in the total of food-borne diseases, and nearly 20% reduction in related deaths.

The discrepancy between these two sets of figures comes from irradiation targeting the deadliest bugs - like Listeria monocytogenes, nontyphoidal Salmonella and E-coli bacteria, which causes little over 10% of the total infections, but inflict two thirds of all deaths. Most of those infected by foods - about two thirds - are hit by a virus, but viral food-borne infections result in only 7% of the total deaths (almost all from Norwalk-like viruses).

According to the FDA, irradiation would kill most of E. coli, Salmonella and Listeria possibly contaminating spinach and lettuce.

Parasite-related deaths from contaminated foods are about three times more numerous than viral, nearly all caused by Toxoplasma gondii (common parasite in warm-blooded animals).

What are the high-risk foods for foodborne diseases? Primarily raw foods of animal origin, and particularly foods that mingle different animal parts, or are made of a number of different animals. Fruit and vegetables don't contain bad bugs on the inside, but can and do get surface-contaminated from water they are washed with after harvest, from fresh manure used as fertilizer, or when handled by infected persons.

Pre-packaged produce that is consumed raw is more risky, since it stays moist, providing better breeding environment for microorganisms.

Looking at the foods associated by the CDC (U.S. Centers for Disease Control) with the above worst infection-causing offenders, some of the typical high-risk foods are, more specifically:

  undercooked beef (E. coli) shellfish (Norwalk-like virus)  
pork, lamb and venison (Toxoplasma gondii)
unpasteurized milk (Salmonella, E. coli, Listeria)
inadequately pasteurized milk (Listeria)
salami (E. coli)
fresh soft cheese (Listeria)
eggs (Salmonella)
hot dogs (Listeria)
egg salad (Shigella)
ready-to-eat deli foods (Shigella, Norwalk, Rotavirus, E. coli, Listeria)
raw fruit and vegetables (E. coli, salmonela)
unpasteurized juice (Salmonela, E. coli).

Undercooked poultry, unpasteurized milk and comtaminated eggs or water also can contain Campilobacter jejuni bacteria, causing more foodborne disease in the U.S. - about 14% of the total, and 1/2 of all bacterial - than any other pathogen. Even with the fatality rate as low as 1 in 20,000, this diarrhea-causing bug still kills more people than E. coli (its two most dangerous strains), which has about 17 times higher fatality rate (fatality rate for nontyphoid Salmonella is 1 in 2,400, and 1 in 300 for Toxoplasma gondii).

So how much safer will make you irradiating spinach and iceberg lettuce? The last spinach related outbreak back in 2006 killed three people and sickened nearly 200. Even if it would be happening every year, that would still make

less than 1/5 and 1/2000 of a single percent of the yearly total,

respectively. Why is the FDA bothering with it at all?

It seems safe to assume that it yields to producers - or good portion of them - who find irradiating economically most feasible in reducing the risk of having their products recalled, or even being shut down. In addition to prolonging shelf life, it is insurance against always possible produce contamination from manure, water or infected handlers.

But - what is the price of this insurance? Does it come only in nickels and dimes, making produce more expensive, or you could, possibly, also pay with your health?

The FDA points out that there is no radiation residues left in irradiated foods. And that irradiation will reduce the risk of most threatening bacterial strains in spinach and lettuce, without compromising consumer safety, or the texture and nutritional value of irradiated foods.

Is food irradiation really as perfect as it makes it sound?

Not quite. Turns out, the list of objections is rather long, and starts with the very basis on which the FDA has approved of its limited use for foods back in 1963 (wheat and wheat flour). Among hundreds of studies on health effect of irradiated foods - nearly all on animals -

quite a few have documented adverse health effects,

including increased tumor formation, reproductive failures and kidney damage.

Even those several studies referred to by the FDA before the initial approval of food irradiation are no exception. The two English studies, according to their FDA reviewers, posed substantial problem for interpretation: there were differences between in the group of rats fed with irradiated (0.2kGy) wheat - for instance, higher stillbirth rate and unexplained abnormalities - but the small number of animals may have prevented them to become statistically significant.

In two of the three French studies, the dose of radiation was less than 0.5kGy, a small fraction of what is used on foods for human consumption. And in the German study, the animals fed irradiated foods had significant weight loss and reproductive defects, both corrected by vitamin supplementation (particularly vitamin E).

The only study on humans available, was on five malnourished children in India, fed with 0.75kGy irradiated wheat (Srikantia et al. 1973). While the children gained weight, and had normal serum albumin and hemoglobin level, after only four weeks four of them had developed gross chromosomal abnormality (polyploidy, abnormally large multiplication rate) in their bone marrow cells. It returned to normal 26 weeks after the irradiated wheat was removed from their diet.

When wheat was stored for 12 weeks after irradiation, there was no chromosomal abnormality - nor increase in prenatal deaths in the simultaneous study on mice - within the period of observation.

Interestingly, the FDA publicly interpreted these result as supportive of their notion that irradiated foods are safe, which prompted professor Srikantia to respond by reiterating that consumption of irradiated wheat is associated with "undesirable consequences", and that irradiated wheat should be stored for at least 12 weeks before it can be used for food.

All of the above is neither comforting nor convincing when it comes to the subject of health safety of irradiated foods. Noting that

most of the studies used significantly lower radiation doses
than those eventually approved by the FDA,

it is scientific fact that exposing foods to radiation of 0.25-70kGy (most of them in 1-10kGy range) used by the industry, causes significant, unpredictable and only partly known molecular changes within it. These changes are independent of the form of radiation (electron beams, x-rays or nuclear gamma rays). Radiation energy splits molecular chemical bonds, creating free radicals, which then go on to continue to alter food molecules long after the irradiation stops.

This results in the formation of so called "radiolytic products", which include toxic, carcinogenic and mutagenic substances, some known, some not. For instance, one of the radiation effects on unsaturated fats is transformation of benzo-pyrenes to mutagenic benzo-pyrene quinones. It is more pronounced in oils with low vitamin E content, like some of fish oils (it is probably due to vitamin E, being antioxidant, partly neutralizing free radicals and getting destroyed in the process).

Lipid peroxidation caused by free radicals makes them unhealthy, damaging cellular processes similarly to the way trans fatty acids do.

Irradiation also converts nitrates to nitrites, reactive molecules forming nitrosamines, known carcinogens, in their interactions with nucleic and amino acids.

This is only a small part of complex molecular changes inflicted to foods by irradiation, but it already doesn't look rosy. It can be expected that antioxidant-rich foods will be generally less adversely affected by irradiation, but

at a price of losing more in their nutritional value.

Radiation also damages other important nutrients, like enzymes, and can turn foreign chemical present in food (additives, pesticides) into radiolytic products of unknown health effects.

The FDA, while aware of these facts, maintains that the risk is acceptable. At the same time, it admits that the available scientific literature does not provide definitive evidence that irradiated foods are safe. Plainly put,

they think it is safe, but do not guarantee it.

Can we trust their objectivity, or assume bias toward consumer safety?

Not really. The FDA showed it clearly this past year, with its proposal that irradiated foods can be labeled not as irradiated, but "electronically pasteurized", or "cold pasteurized". Is that fair to 71% of consumers who, according to June 2007 Consumers Union survey, do not want to buy and consume irradiated foods. Of course not.

Other than providing only a limited protection against foodborne diseases, at a price of making food less healthy or unhealthy, other drawbacks of irradiation are:

it does not sterilize food, which can be bio-contaminated after irradiation, just as easy as non-irradiated foods

it makes possible for food producers to sell foods of inferior quality that couldn't be legally sold if not irradiated (primarily meats); it also makes it easier for them not to address the primary cause of food contamination: unsanitary conditions during production and packaging 

it will likely create strains of radiation-resistant pathogens, which will either make irradiation increasingly less efficient as protective measure, or require higher doses of radiation

In the meantime, the list of irradiated foods is growing. Partial list includes beef, pork, lamb, poultry, wheat, wheat flour, vegetables, fruits, eggs in the shell, seeds for sprouting, spices, herbal teas...

Is there better alternative?

Of course. For one, foodborne infectious diseases are no different than other infectious disease in that they are significant danger mostly for those with compromised immune system. Take good care of it, and it will give you much more protection than irradiating foods. Those who cannot have strong immune system, can rely on proper cooking, safer food choices, handling and preparation. Again, these precautionary steps are likely to offer better protection, without all the negatives of food irradiation.