In a food supplement enforcement exercise carried out by the Food Standards Agency (FSA) in 2003, 48 products from a variety of outlets were examined. 11 supplements were completely irradiated and 13 had an irradiated ingredient.
But Health Food Manufacturers Association (HFMA) director David Adams believes that the study needs to be put into context.
"The FSA conducted a random market survey in 2002, focusing on supplements that they thought might be irradiated," he told FoodNavigator.
"They were looking particularly at plant material from other countries. They found that slightly under half were irradiated or contained irradiated material.
"A year later, the FSA undertook an enforcement survey, which particularly focused on those products in the first survey. We're talking about a small proportion of food supplements.
"It found that slightly less contained irradiated material, which is strongly indicative that action had been taken."
Publication of the results was deferred until 2006 pending enforcement action by local authorities.
In addition, the HFMA said that there are a number of issues surrounding the enforcement survey that must be taken into account. The samples taken in 2003 were taken very soon after the initial test in 2002.
Adams points out that these supplement products often have a long shelf life, and that as a result, the enforcement survey might not have picked up on the improvements made in the preceding months.
The HFMA added however that it was pleased that the agency has confirmed that this is not a food safety issue. "It's a question of legality," said Adams.
Irradiation, used to prolong the shelf life of food products and/or to reduce health hazards, is a physical treatment of food with high-energy, ionising radiation. It exposes food to electron beams, X-rays or gamma rays, and produces a similar effect to pasteurisation, cooking, or other forms of heat treatment, but with less effect on look and texture.
Although an accepted manufacturing process in the USA and approved for use since 1963 to control mould and insect infestation in wheat and to inhibit the growth of sprouts on potatoes, European consumers remain sceptical of the food safety aspect and as a result, it is largely illegal.
At the moment, the only foods that may be irradiated and sold freely across the EU are dried aromatic herbs, spices and vegetable seasonings.
The HFMA says it has assured the FSA that much additional work has been undertaken to eradicate the incidence of irradiation in Member company food supplement products.
"We would certainly expect improved results now," he said.
However, the association has pointed out that this work is hampered by both the lack of a reliable and accessible screening test method and reported variability in test results.
"Methods for screening for irradiated materials are not that widespread, and are not always 100 per cent accurate," said Adams. "The FSA has been helpful however in organising to discuss these issues and there will be a technical workshop in autumn. After that we plan to publish Best Practice guidelines for our members."
The HFMA is the UK's leading trade association for specialist food supplements and health products.