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Food irradiation is the practice of subjecting food to high doses of ionizing radiation - gamma radiation, X-rays or electron beams - in order to kill germs and prevent food poisoning. Irradiation extends the shelf life of foods and eliminates pathogens. At higher doses, it makes the food suitable for people suffering from deep immunosuppression, such as leukemia patients. Because the technology overlaps two areas of everyday life which are highly prone to woo and pseudoscience - food and nuclear technology - most of the time it is drowning in a tidal wave of bullshit. Lack of consumer acceptance is the primary reason why it is not used to a greater extent.
Uses of irradiation
Irradiation is conducted by subjecting food, typically already in its packaging, to radiation from a particle accelerator or a sample of radioactive material, such as cobalt-60 (which emits gamma rays and electrons as it decays). Bacteria, fungi, insects and parasites die due to DNA damage and inactivation of enzymes.
The primary use of irradiation is to kill germs without heating the food after it is put in its airtight packaging. This allows the sterilization of foods which cannot be pasteurized, such as fresh fruit and vegetables, spices, frozen and raw meat and fish, and complete prepared meals. Additionally, low doses of radiation can prevent sprouting of foods such as potatoes, garlic and onions, and delay ripening.
Irradiation requires large and expensive equipment, although the technology can also be used for other applications such as sterilizing medical equipment, cosmetics, and packaging. In 2012 the UK Food Standards Agency reported that there were more than 20 sites in the EU and 10 outside the EU, "three in South Africa and India, two in Thailand and one each in Turkey and Switzerland". The Turkish site is GammaPak which offers a range of Cobalt-60 sterilisation.
Irradiation will not inactivate metabolic enzymes naturally present in food, which cause its slow decomposition over time. It can't be used to "fix" partially spoiled food, as the toxins already produced by microorganisms are not destroyed. (Pasteurization, by contrast, can eliminate those toxins that break down on exposure to heat, such as the botulism toxin.) Doses of radiation used in food processing typically do not kill viruses. Foods high in unsaturated fat, such as nuts and vegetable oils, tend to taste bad after being subjected to radiation.
Irradiation facilities tend to be capital intensive, with costs in the range of $1 million - $5 million.
Mostly fictional concerns of opponents
The most obvious fear is that irradiated food is radioactive itself and will cause you to grow a tail or an extra hand. In reality, all food is slightly radioactive, and irradiation does not increase its radioactivity. This is similar to visible light: no matter how long you sunbathe, you will not start glowing in the dark, even though sunlight is a form of radiation. Inducing radioactivity in food is only possible using neutrons, but irradiation does not use them. This fear is probably rooted in the all-too-common confusion — eagerly exploited by anti-nuclear scaremongers — between radiation (receiving rays produced by nuclear reactions) and radioactive contamination (having physical particles of radioactive materials on or in oneself).
Other arguments against food irradiation are listed below.
- Irradiation would hide hygiene problems at manufacturing plants. The inherent assumption is that maintaining hygiene standards is a goal in itself, whereas in fact the actual goal is safe food, with hygiene standards being only a means to that end. Proponents of irradiation do not think that irradiation is a substitute to hygiene, as irradiation is not equivalent to complete sterilization. Additionally, it cannot remove toxins already produced by microorganisms.
- Irradiation reduces the nutritional value of food. This is true in case of some micronutrients such as vitamins. Protein, carbohydrates and fat are not affected to any significant degree. The loss of vitamins is lower than in alternative methods, such as canning, drying or pasteurization. Slightly less nutritious food is better than toxic food.
- Irradiation extends the shelf life of food. It requires some really crazy logic to consider this a disadvantage. Longer shelf life reduces the amount of food lost to spoilage and allows smaller shops to keep a wider inventory. The only possible detrimental effect is that food might lose some nutrients when stored over long periods of time - but again, slightly less nutritious food is better than spoiled food or no food at all. An extended shelf-life also reduces the cost of a particular type of food, which plays into an unspoken prejudice that cheap food is synonymous with junk food
- Irradiated food loses nutrients over time faster than non-irradiated food. Persistent free radicals are sometimes proposed as a chemical basis. They are supposed to somehow "catalytically" destroy antioxidants. However, such catalytic action is chemically impossible - when a free radical reacts with a molecule of an antioxidant, both molecules are inactivated. The fact that some of the radicals persist in irradiated food indicates that they simply failed to react with antioxidants.
- Irradiation of fats produces 2-alkylcyclobutanones (2-ACBs), which might be carcinogenic. This is trying to answer the wrong question. Coffee contains over 1000 different compounds, and 19 of the 28 that were tested are rodent carcinogens. Despite this, coffee consumption is not a risk factor for cancer. A feeding study using the complete product is a better estimate of cancer risk than analyzing its chemical content. The same logic can be applied to irradiated food and 2-ACBs. Animal studies showed no carcinogenic effect of irradiated food, even at very high radiation doses. Therefore, whether isolated 2-ACBs are carcinogenic is irrelevant.
- Food woo
- FAQ on radioactivity and nuclear technology
- Microwave oven, which uses a very different kind of radiation
- Raisins, which are grapes irradiated with yet another sort of radiation
- See the Wikipedia article on food irradiation.
- Irradiated food, UK Food Standards Agency, 26 Apr 2012
- GammaPak website
- University of Wisconsin, Madison - The Facts about Food Irradiation
- Position of the American Dietetic Association: Food Irradiation
- New York Times - Spinach and Peanuts, With a Dash of Radiation
- Which is exactly the opposite of the actual case: junk foods tend to be convenience foods, which in the long run are considerably more expensive per meal than foods prepared at home from basic ingredients. Convenience foods are an extremely expensive luxury, as people on food stamps, or otherwise on tight food budgets, rapidly learn.
- New York Times - EATING WELL; Questions on Irradiated Food
- The causes and prevention of cancer: the role of environment
- Coffee consumption and risk of gastric and pancreatic cancer-A prospective cohort study