America has experienced a spate of virulent cases of food poisoning over the past several years, and scientists are convinced that irradiation is the most effective way of ridding foods of the causal bacteria such as Salmonella and Escherichia coli.
Spearheading the latest campaign is new research from the US Department of Agriculture (USDA), which tested irradiation against a waterwash and a chemical treatment. Irradiation was the only one of the three that removed virtually all of the E. coli bacteria from lettuce and spinach leaves (Proceedings of the 235th National Meeting of the American Chemical Society, April 13, 2008).
Around 40 countries around the world license irradiation processes to some extent, but the US is one of the more liberal in its use. Most of the frozen meats sold in American supermarkets have been irradiated, and health campaigners are worried that all vegetables and fruit will soon be as well.
In the UK, only herbs, spices and vegetable seasonings are currently allowed to be irradiated-and these all have to be properly labelled as such-although food inspectors have discovered that other foods are being illegally irradiated. In one survey, they discovered that, of the 18 purchases of shellfish at supermarkets in Suffolk, seven had been irradiated.
Nevertheless, the food industry lobby continues to urge the EU to expand the range of foods that can be irradiated.
What is food irradiation?
The use of ionizing radiation for food preservation began in the US in the 1920s. It uses electron beams, X rays or gamma rays to kill bacteria, delay fruit from ripening, and stop potatoes and onions from sprouting.
The process creates short-lived free-radical molecules that kill micro-organisms, a process that also occurs when we cook, chop or grind food. But irradiation also kills bacteria directly by affecting their DNA.
Yet, despite the claims of the food industry that irradiation is the answer to food poisoning, it fails to prevent certain toxins such as botulinum, produced by the bacteria that cause botulism, viruses such as the ones that cause foot-and-mouth disease and hepatitis, and the prions that cause BSE, or 'mad-cow disease', as these
are all resistant to irradiation (Center for Food Safety. Food Irradiation, 2007; www. centerforfoodsafety.org/food_irrad.cfm).
Is irradiated food safe?
Although irradiation causes chemical changes in food, official government groups nevertheless persist in assuring the public that the process is safe. What's more, America's Food and Drug Administration (FDA) is making moves to disguise the fact that food has been irradiated by either removing all labelling or changing the wording to 'cold pasteurized'.
Studies carried out by the USDA have been quick to praise irradiation, and have even described the process as "an underutilized technology" (Nutr Clin Care, 2004; 7: 149-55). But researchers at the University of Texas Medical Branch point out that most studies have only examined the effectiveness of irradia-tion and not its safety. "Current evidence does not exist to substantiate the support or unconditional endorse-ment of irradiation of food for consumption," they conclude (Int J Hyg Environ Health, 2004; 207: 493-504).
The few studies that have examined safety issues have come up with alarming results. Researchers at the Friedrich Schiller University in Jena, Germany, discovered that irradiation creates a new class of contaminants-namely, 2-alkylcyclobutanones-when used on fats. The contaminants are toxic and may speed up the progressof colon tumours, they say (Mutat Res, 2006; 594: 1-9).
The carcinogenic effects of this new contaminant-which has never been found in non-irradiated foods-was confirmed in a separate study on rats (Radiat Phys Chem, 2002; 63: 431-5).
Irradiation also creates another potential carcinogen-furan-when fruit and vegetables are irradiated. Fruits that have high levels of simple sugars and a low pH are especially likely to form furan when irradiated(J Food Sci, 2008; 73: C79-83).
Even the process in itself is not safe. The ionizing radiation used on foods-usually cobalt-60 and cesium-137-are known carcinogens. Indeed, a study of workers, exposed to ionizing radiation at the Savannah River Site nuclear plant in South Carolina, discovered that they experienced higher-than-average rates of cancer (Am J Indust Med, 2007; 50: 881-91).
What else does it do to food?
The FDA assures the American public that "the irradiation process may cause a small loss of nutrients but no more so than with other processingmethods, such as cooking, canning or heat pasteurization".
This is simply not true. Aside from creating possible carcinogens, irradi-ation also strips food of its essential nutrients. Levels of vitamin E are reduced by around 25 per cent, and vitamin C by up to 10 per cent. This loss is compounded by the extended shelf life permitted by irradiation and when the food is eventually cooked (Position Statement of the Food Commission, July 2002; www.foodcomm.org.uk/irradiation_ probs.htm).
Irradiation can destroy up to 80 per cent of the vitamin A in eggs, up to95 per cent of the vitamin A and lutein in green beans, half the vitamin A and lutein in broccoli, and 40 per cent of the beta-carotene in orange juice. Irradiation also doubles the amount of trans fats in beef (Center for Food Safety. Food Irradiation, 2007).