Expert: Dr. Leo Nollet - 4/10/2011

Question
Doctor, here in the USA, foods may be irradiated to prolong shelf life. Have you heard of any studies linking consumption of such foods to higher rates of cancer, or any other illnesses?
Also, here in the USA, water is sometimes purified with UV light-have you heard of any health problems associated with drinking UV treated water?
Thanks!
Steve

Answer
Dear Steve,
First question. I hope this information helps.

Food Irradiation
Food irradiation is perhaps the single most studied food processing technology for toxicological safety in the history of food preservation. Studies pertaining to the safety and nutritional adequacy of irradiated foods date back to the 1950s and were frequently associated with the use of radiation to sterilize foods.

Hundreds of short-term and long-term safety studies led to the approval of one or more foods for irradiation by presently more than 60 countries. These studies are thoroughly reviewed in “The Safety and Nutritional Adequacy of Irradiated Foods,” published by the World Health Organization in 1994.

In the United States, the Food and Drug Administration reviewed the available studies for the quality of experimental design, rigor, and statistical validity before approving irradiation of a variety of food products including grain, fruits and vegetables, spices and dried herbs, meat and poultry, and eggs for human consumption.

The vast majority of the studies failed to find adverse effects associated with consumption of or exposure to irradiated foods. Not surprisingly, a small number of studies produced equivocal results pertaining to the safety of irradiated foods. However, in-depth review of those studies determined that they were deficient in experimental design, used insufficient numbers of test subjects for proper statistical analysis, or suffered from experimenter error.

The preferred method for assessing the toxicological safety of irradiated foods has been long-term feeding studies in animals, often for multiple generations. Toxicologists prefer to use animals for these types of evaluations, as opposed to using people or their children, for obvious reasons. Swallow reported that animals used for toxicological research, fed diets of radiation-sterilized foods for 40 generations, suffered no ill effects from consumption of irradiated foods.

Thayer and others reported that rodents fed diets of radiation-sterilized chicken meat (45–68 kGy) did not suffer an increased risk of cancer or birth defects. The same study also failed to find adverse effects associated with long-term consumption of irradiated meat in beagle dogs. De Knecht-van Eekelen and others conducted single- and multiple-generation feeding studies in rats without finding adverse effects due to consumption of the irradiated chicken diet. Poling and others reported no evidence of changes in survival, histopathology, or reproduction in three generations of rats fed radiation-sterilized ground beef. Feeding studies in animals have been very consistent in the lack of adverse effects associated with long-term consumption of irradiated foods.

2nd question
UV-treated water is safe to drink. UV treatment does not add chemicals or change the chemical composition of the water. When properly sized and installed on a visually clear water source, UV can effectively protect from microorganisms in the water. Prolonged storage of water after UV treatment is not recommended.