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Will Science Decide the Fate of Food Irradiation?
By Paisan Loaharanu
The safety of foods is normally decided by science, supported by a large body of data compiled from scientific research, evaluated by independent experts who are appointed by national or international authorities. Terms such as "acceptable daily intake (ADI)" or "maximum residue limits (MRLs)" are commonly used by regulatory authorities to certify the safety of food additives and pesticide residues, respectively, in food based on scientific research.
Yet FOODproductiondaily.com on December 4 published an article called "Irradiated foods highlighted during week of protest" filed under "Breaking News on Food Processing and Packaging -- Europe." The article caused me great alarm -- not because it described "week-long coordinated protests worldwide against the technology (food irradiation) by consumer groups" but because it misleadingly extracted information from "a new report recently published by U.S.-based Food & Water Watch." The article was derived almost exclusively from that one source, though Food & Water Watch is not known for its scientific expertise on food irradiation but is well known for its ideological opposition to this technology. A lot of information contained in the article ranged from half-truths to no-truth, and its hidden motive was to confuse and mislead the reader about the safety and effectiveness of food irradiation as a food processing method.
We were not aware of any public protest rallies against irradiated food held in the U.S., Italy, France, the Philippines, Australia, New Zealand, and Brazil. Unfortunately, the article was vague about where and when these rallies occurred, who was in attendance, and whether they were supported by national consumer organizations.
Here are some of the misleading claims of the article and my rebuttals:
CLAIM: Food irradiation can "kill up to 99% of pathogens," but (it is implied) does not kill the rest, leaving food still contaminated.
FACT: For pathogen control, the process (food irradiation) uses a dose sufficient to kill about 4-5 log cycles (99.99 to 99.999%) of target pathogens, e.g., _E. coli_ 0157:H7 or _Listeria monocytogenes_. The remaining pathogen is therefore 0.01-0.001% of the initial number of pathogens present in the food. Normally, fewer than ten cells of pathogens are present in one gram of food. Anyone familiar with food microbiology would know that the surviving fraction of a pathogen cell cannot proliferate (grow and multiply to cause illness to consumers). Therefore, foods irradiated for pathogen control are essentially free from target pathogens (there is no absolute zero in science!) -- and without causing a significant change in the food's sensible qualities.
CLAIM: "The EU has placed a ban on further irradiation approvals due to scientific research questioning the safety of some chemicals formed when food is exposed to radiation."
FACT: The EU never placed a ban on further irradiation approvals. Rather, the European Commission could not achieve a consensus on the positive list of irradiated foods (there were several types) to be allowed for irradiation in all EU member countries, as required by its Directive 1999/3. However, the Directive allows spices, herbs, and dried aromatic substances to be irradiated and traded freely in all EU member countries, with labeling requirements as stated in Directive 1999/2/EC. Countries that had already approved other irradiated foods before the issuance of the Directive in 1999 (e.g., Belgium, France, Italy, the Netherlands, Spain, and the UK) can continue to irradiate foods based on their earlier national approvals.
CLAIM: The UK and Irish authorities reported that several samples of food supplements sold in their countries, either wholly irradiated or containing irradiated ingredients, were not labeled as irradiated (as required by Directive 1999/2/EC).
FACT: While this claim is technically accurate, it does not contain all relevant facts. First, it should be pointed out that irradiated food supplements cause no health hazard in any way. It should also be noted that in several countries food supplements and food ingredients such as spices, herbs, and dried vegetable seasonings are normally fumigated by ethylene oxide. No labeling is required for fumigated foods regardless of the toxicity of the fumigants used. The fact is ethylene oxide was banned for fumigating food and food ingredients in Europe by the European Commission in 1991, due to its toxicity to humans and the environment. I never received satisfactory answers from the Irish and UK food authorities about whether food supplements marketed in the UK and Ireland have been fumigated by ethylene oxide (despite it being banned in their countries) and whether they have detected ethylene oxide residues in food supplements and food ingredients.
CLAIM: Radiolytic products -- cyclobutanones -- have been linked to genetic damage, says Food & Water Watch.
FACT: Preliminary studies conducted in Germany in late 1990s showed potential toxicity of 2-alkylcyclobutanone compounds (2-ACBs) when high concentration and highly purified compounds were used in in vitro and in vivo toxicity tests.(1,2) However, the results of these studies were purely academic, since the tests were done on pure 2-ACBs compounds at concentration thousands of times higher than those expected to occur in irradiated fat-containing foods, and the authors used a non-validated assay (a Comet Assay) as one of the tests to assess the toxicity. Other, validated tests, including the Ames test, did not show toxicity of 2-ACBs. Despite the caution comment by the authors that it would be hasty to use the results of the studies to draw a conclusion about a health hazard in consuming irradiated foods containing 2-ACBs, several activist groups including Food & Water Watch and the affiliated group Public Citizen chose to highlight this potential toxicity of 2-ACBs and to alarm the public about a supposed cancer risk.
Nonetheless, the results of multi-generation animal feeding test involving more than 135 metric tonnes of chicken sterilized by high-dose irradiation (59 kGy), which definitely contained 2-ACBs, never showed any toxic effects.(3) More recent studies conducted by Sommers (4,5) found no mutagenic effect of 2-dodecylcyclobutaones and related compounds.
It should be made clear that overwhelming scientific evidence on the safety of irradiated foods compiled in the past five decades, periodically evaluated by several teams of national and international experts, especially those appointed by FAO, IAEA and WHO since 1960s, showed no health problems from consumption of irradiated foods, regardless of absorbed dose.
Thus, the time has come for Food & Water Watch and other non-scientific groups to stop using irrelevant data to misinform the public about the potential toxicity of irradiated foods.
We should not use irrelevant claims but rather sound science to judge the safety of our food. If we were going to be consistently paranoid and eat nothing about which even hypothetical or minute potential risks had been discussed, we would stop eating a number of common foods, e.g., boiled eggs because of trace amount of benzene; bread, cake, pizza, and any carbohydrate-containing foods subject to high heat because of acrylamide; barbecued meat, chicken, fish, etc. because of benzopyrenes; and so forth, as these compounds could cause cancer in human and animals in massive (and irrelevant) doses. You could even sensationalize these concerns further by suggesting that we should not allow any heating of food, since it produces compounds that could perhaps be harmful in massive doses -- but this would be a stupid, tragic mistake for food-loving humans everywhere.
There are overwhelming data to support the safety and effectiveness of food irradiation, much more than the data supporting safety claims for many other food-processing technologies. Credible scientific and health organizations including the World Health Organization, the Food and Agricultural Organization of the United Nations, the Centers for Disease Control and Prevention, the American Medical Association, the American Council of Science and Health, the Institute of Food Technologists, and more have endorsed food irradiation as a safe method for sanitary and phytosanitary treatment for food.
Even an international consumer movement such as Consumer International (CI), affiliated with relatively credible consumer organizations worldwide, has ranked food irradiation low on its list of consumer worries. There are of course extreme groups such as Food & Water Watch, whose views are not acceptable by CI, who oppose the use of food irradiation for ideological reasons. But those groups should not inspire journalists to offer consumers misleading information.
References
1. Delincee, H. and Pool-Zobel, B.L. (1998) Genotoxic properties of 2-dodecylcyclobutanone, a compound formed on irradiation of food containing fat. Radiat.Phys.Chem., 52,39-42.
2. Burnouf, D., Delincee, H., Hartwig, A., Marchioni, E., Miesch, L., Raul, F., Werner, D. (2002) Etude toxicologique transfrontaliere destinee a evaluer le risque encouru lors de la consommation d'aliments gras ionises / Toxikologische Untersuchung zur Risikobewertung beim Verzehr von bestrahlten fetthaltigen Lebensmitteln. Eine franzosisch-deutsche Studie im Grenzraum Oberrhein. Rapport final / Schlussbericht INTERREG II.Projet / Projekt No. 3.171. (Marchioni, E., Delincee, H., Eds.) Berichte der Bundesforschungsanstalt fur Ernahrung, Karlsruhe, BFE-R--02-02, pp. 1-198. (also available online: http://www.bfa-ernaehrung.de/Bfe-Deutsch/Information/bfeber91.htm )
3. Thayer, D.W., Christopher, J.P., Campbell, L.A., et al. Toxicology studies of irradiation-sterilized chicken. J. Food Protect. 1987;50,287-288.
4. Sommers C.H. 2-Dodecylcyclobutanone does not induce mutations in the Escherichia coli tryptophan reverse mutation assay. J Agric Food Chem 2003;51:6367-6370.
5. Sommers C.H, Schiestl RH. 2-Dodecylcyclobutanone does not induce mutations in the salmonella mutagenicity test or intrachromosomal recombination in Saccharomyces cerevisiae. J. Food Protect. 2004;67:1293-1298.
Paisan Loaharanu is an Adjunct Professor of Food Safety at Michigan State University and the Former Head, Food and Environmental Protection Section, Joint FAO/IAEA Division.
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