Health Canada has completed a series of public meetings, proposing to add ground beef, chicken, shrimps, prawns and mangoes to the list of foods that may be irradiated.

Currently potatoes, onions, wheat, flour and spices can be irradiated in Canada, but in practice seldom are. Irradiation of food renders pathogens such as Salmonella and Escherichia coli O157:H7 unable to reproduce and is usually administered in the form of gamma rays from radioactive cobalt-60.

Health Canada says it believes the evidence suggests that irradiated food is safe for human consumption. Critics disagree and argue that it is unsafe for human consumption, unnecessary, or environmentally unfriendly.

The Canadian Cattlemen's Association believe the technology will allay fears about the safety of foods such as hamburgers, by reducing the levels of pathogens. Currently microorganisms cause millions of cases of food borne illness and thousands of deaths on a global basis.

Canadian government scientists have reviewed multi-generation studies on a variety of animals fed irradiated foods. They investigated whether irradiation altered vitamins levels or triggered chemical changes in food. They found that irradiation may result in partial losses of the vitamins thiamin, riboflavin and niacin, but concluded that these losses are not nutritionally significant when considering the overall diet. Their final conclusion was that consumption of irradiated foods does not pose a health hazard to the consumer.

Critics point out that there is no room for error at irradiation plants, which hold the radioactive materials. They also note that irradiation creates a variety of chemical by-products that can linger in food. A study by the Federal Research Centre for Nutrition in Germany, found that irradiation created trace amounts of cyclobutanones, compounds which may be genotoxic and even tumour promoting. Irradiation also produces free radicals that may cause cellular/DNA damage.

A spokesperson for Health Canada said that feeding vitamin E to cattle before slaughter can suppress the production of free radicals during irradiation. Critics are concerned that the source of pathogens such as Escherichia coli would not be considered but Health Canada insist that irradiation will complement but not replace safe food handling.

If the list of irradiated foods was extended in Canada, all the foods would be required to be labelled.

A final decision is not expected for months.

RSSL offers an irradiation screening service using PSL (pulsed photostimulated luminescence), a technique developed by Dr David Sanderson at the Scottish Universities Research and Reactor Centre. For more information e-mail enquiries@rssl.com .