U.S. CONGRESSIONAL HEARINGS
INTO FOOD IRRADIATION
House Committee on Energy and Commerce
Subcommittee on Health and the Environment
Excerpted from the testimony of
- S. G. Srikantia, B.Sc.,.B.B.S., D.Sc.
Professor of Food and Nutrition,
University of Mysore, India;
National Institute of Nutrition,
- Donald R Louria, Ph.D.,
Chairman, Department of
Preventive Medicine and Community Health,
University of Medicine and Dentistry, New Jersey
- George L Tritsch, Ph D
Cancer Research Scientist,
Roswell Park Memorial Institute,
New York State Department of Health
- Richard Piccioni, Ph D ,
Senior Staff Scientist,
Accord Research and Educational Associates
New York, NY.
National Institute of Nutrition,
During the course of these studies the Institute made several new and important observations of practical importance and published them in refereed international journals.
The meaning of increased numbers of polyploid cells is not clear , though it is often seen in association with rapidly regenerating tissues and with malignancy [ cancer ] . Whether it signifies either mutational or precancerous changes is not certain. But the meaning of "dominant lethal mutation" is obvious -- it indicated undesirable changes in reproductive performance.
The explanation for the increased polyploidy and the dominant lethal mutation following the ingestion of freshly irradiated wheat, is not clear. It is likely to be an effect of a mutagen formed in wheat during the process of irradiation. The fact that these effects were not seen when stored irradiated wheat was fed, suggests that the mutagen is a relatively unstable substance
Based on these findings the National Institute of Nutrition recommended that unconditional clearance of irradiated wheat was not warranted and that when subjected to irradiation, wheat should be stored for a period of at least twelve weeks prior to being released for consumption....
The Committee of Indian Scientists referred to here, is a two-man committee which consisted of Dr. P.C. Kesavan and Dr. P.V. Sukhatme, whose report, according to the federal register's citation, was submitted to the Joint FA0/WHO/IAEA Expert Committee on the Wholesomeness of Irradiated Food, held at Geneva in 1976.
This statement [ by the U.S. FDA ] leaves the reader with the impression that the [ Kesavan-Sukhatme ] report was discussed by the Joint Expert Group and that the findings in the report were endorsed by it. This would be at variance with the facts because the report was NOT submitted to the Joint Expert Group and therefore was never discussed . I can vouch for this since I was a member of that Expert Group. At that meeting, the [ earlier ] findings of the National Institute of Nutrition were accepted, as is reflected in the published reports of the Proceedings....
The FDA has now accepted that it was indeed incorrect to have cited that the Kesavan-Sukhatme report had been submitted to the Expert Group in 1976. It is unfortunate that many of the original readers of the Federal Register may not get to know the truth....
The [ Kesavan-Sukhatme ] report was a confidential document. After receiving the report, the government of India sent it to the Director, National Institute of Nutrition, for his views and comments The Institute's Director sent his comments to the government, which was also a confidential document. As of today, to the best of my knowledge neither of these documents has been made public. It was therefore surprising to learn that the FDA has a copy of the confidential Kesavan-Sukhatme report, and that it has accepted its findings without being aware that the conclusions of that report had been questioned. In his comments the Director, National Institute of Nutrition, has not only refuted some of the statements made in the report, but also provided additional evidence to back up the Institute's conclusions....
The FDA has committed a serious error of judgment. Had it seen the Institute's rejoinder to the Kesavan-Sukhatme report, surely, it would have been in a better position to evaluate that report....
It is indeed very strange that aspersions should have been cast on the scientific honesty and integrity of the Institute's workers a full ten years after the work was published. It is even stranger that the two scientists who allegedly made these statements have denied having made them when they were approached by me. The person who acted as Chairman at the panel discussions has, so far, not responded to my letter. Clearly, there is more here than meets the eye. It is very unfortunate that attempts are being made to discredit the Institute's work by resorting to questionable methods.
I wish to reiterate that the Institute has NOT withdrawn anything which it said earlier on this subject and stands fully behind all that it has published. Indeed, its stand has received support from the publications of both Renner and Anderson and coworkers. The Institute also does not agree with the Kesavan-Sukhatme report. It stands behind its statement that eating irradiated wheat-based diets is associated with undesirable consequences and reiterates its recommendation that should wheat be irradiated for human consumptions it must be stored for at least 12 weeks before being released for use.
Two of the studies are in English, three in French, and one in German. The two in English were reviewed by five epidemiologists and biostatisticians. Their judgment was that both studies posed substantial problems in interpretation. In one of the two studies, published in 1964, the authors note "in many cases statistical comparisons were not possible. However, examination of the data intuitively suggests that the differences have no real significance."
In actuality, there were differences between controls and those rats given irradiated wheat, but the small number of animals may not have permitted statistically significant differences to be found. There were unexplained stillbirths in the litters of rats given wheat irradiated with twenty thousand rads; recalculation of that stillbirth rate shows a significant increase. This study is hardly an endorsement for the safety of irradiating food. The other study, intensively reviewed, has similar problems with statistical significance, unexplained deaths, and abnormalities in animals given irradiated foods that are treated dississively and virtually ignored.
So the two studies in English, instead of documenting safety, raise questions about the safety of food irradiation. Additionally, one of the studies suggests that older animals may be more susceptible to adverse effects when eating irradiated foods.
What about the French and German studies? In two of the three French studies, the dose of radiation to food was less than fifty thousand rads; this small dosage makes the conclusions difficult to apply to the human situation. No specific adverse effects were noted. The German study showed no adverse effects directly, but showed other adverse effects that will be discussed subsequently.
Taken together, these studies could not possibly establish the safety of food irradiation. Indeed, two of the studies suggest the technology is not safe.
In the 1964 report the authors noted that both controls and those fed irradiated wheat were given supplementary vitamins; in part, "this was done to avoid the reproductive difficulties that were attributed to destruction of vitamin E induced by radiation". In the German experiment, in the first year of analysis those animals given irradiated foods weighed significantly less than controls and showed reproductive defects; both these abnormalities were corrected by administration of vitamins, particularly vitamin E.
There are now many other data indicating that irradiation of foods can reduce the nutrient value of those foods. Additionally, further processing of the food, for example by cooking, may result in accelerated nutrient depletion compared to unirradiated foods.
The supporters of food irradiation treat the potential damage to the nutrient value of food as if it were unimportant or nonexistent That is a major mistake. If the nutrient value of food is reduced, then the argument for food irradiation prolonging shelf life is undercut. Surely, it would not make sense to prolong shelf life if the foods are nutritionally defective.
To summarise, I do not believe that irradiated foods have been shown to be safe for general consumption. Equally important, the effects of irradiation on the nutrient contents of food are not established. I believe the prudent action to take is to prohibit the irradiation of food until the basic issues are sorted out. To do less would be irresponsible.
I am opposed to consuming irradiated food because of the abundant and convincing evidence in the refereed scientific literature that the condensation products of the free radicals formed during irradiation produce statistically significant increases in carcinogenesis, mutagenesis and cardiovascular disease in animals and man. I will not address the reported destruction of vitamins and other nutrients by irradiation because suitable supplementation of the diet can prevent the development of such potential deficiencies. However, I cannot protect myself from the carcinogenic and other harmful insults to the body placed into the food supples and I can see no tangible benefit to be traded for the possible increased incidence of malignant disease one to three decades in the future.
Irradiation works by splitting chemical bonds in molecules with high energy beams to form ions and free radicals. When sufficient critical bonds are split in organisms contaminating a food, the organism is killed. Comparable bonds are split in the food. Ions are stable; free radicals contain an unpaired electron and are inherently unstable and therefore reactive. How long free radicals remain in food treated with a given dose of radiation or the reaction products formed in a given food cannot be calculated but must be tested experimentally for each food. Different doses of radiation will produce different amounts and kinds of products.
The kinds of bonds split in a given molecule are governed by statistical considerations. Thus, while most molecules of a given fatty acid, for example, may be split in a certain manner, other molecules of the same fatty acid will be split differently. A free radical can either combine with another free radical to form a stable compound, or it can initiate a [chemical] chain reaction by reacting with a stable molecule to form another free radical, et cetera, until the chain is terminated by the reaction of two free radicals to form a stable compound. These reactions continue long after the irradiation procedure.
I am bringing this up to give you a rationale for the vast number of new molecules that can be formed from irradiation of a single molecular species, to say nothing of a complicated mixture as a food. Furthermore the final number and types of new molecules formed will depend on the other molecules present in the sample. Thus, free radicals originating from fats could form new compounds with proteins, nucleic acids [DNA] , etc. These considerations lead to the following conclusions:
The first study I will discuss deals with the danger of irradiation of foods which contain unsaturated fats. This is particularly timely since the American public is being advised to reduce total fat intake, especially intake of saturated fats, because of the excellent correlation [with] cardiovascular disease and some forms of cancer. Unsaturated fat consumption is indeed increasing in the United States. When poly-unsaturated fats are exposed to one to four kilogray (100-400 thousand rads) large concentrations of peroxides are formed and a concomitant oxidation of benzo-pyrenes to mutagenic benzo-pyrene quinones takes place. This response is dose dependent. Unsaturated fats such as cod liver oil and mackerel oil showed much greater benzo-pyrene quinone formation than saturated fats (like coconut oil) or fats containing vitamin E, such as corn oil.
This recent study of 1986 clearly shows that peroxidation of lipids by irradiation produces known carcinogens. Not emphasised in this paper is that peroxidation of lipids also results in their cross-link polymerization in a manner akin to the drying of oil-based paint These polymers cannot be digested by our digestive enzymes and will likely be deposited as insoluble plaques in blood vessels. This would have analogous results as the deposition of insoluble cholesterol plaque is well known to lead to high blood pressure and cardiovascular disease in some individuals. In a consensus statement frequently quoted to document the safety of irradiated food by proponents the following statement is made:
"In this research, several anomalies appeared in the test animals (for example, hemorrhages, ruptured hearts and vitamin deficiencies) but these were related to feeding the test animals food they did not customarily eat, and not to treating the foods with ionizing energy"
Hemorrhages and ruptured hearts bring to mind acute and extremely high elevation of blood pressure. I would question the prudence of instigating a study of feeding animals food they do not customarily eat and then dismissing adverse effects for this reason. I do not believe such a statement could appear in the refereed scientific literature.
I would next mention the effects of irradiation on nitrate in foods. Irradiation converts nitrate to nitrite in a dose dependent manner. Mutagenesis is directly proportional to nitrite concentration. Nitrite is a reactive molecule and reacts with nucleic acids and various amino acids in protein and forms the known family of carcinogens known as nitrosamines. These have been demonstrated to be potent carcinogens in man.
Now let me turn to what I believe to be the most convincing and comprehensive group of studies to demonstrate the harmful effects of irradiated food. In 1975 were reported the results of feeding five malnourished Indian children wheat irradiated with 75,000 rads. This wheat produced weight gain, serum albumin, and hemoglobin levels indistinguishable from what was found with unirradiated wheat. However, four of the five children showed gross chromosomal polyploidy four weeks after initiation of the feeding program. Chromosome number returned to normal twenty six weeks after the feeding was stopped. This is unequivocal evidence of a potent mutagen in irradiated wheat. I would remind you that the high lung cancer incidence in the United States in 1982-83 was 80 per 100,000, which is equivalent to 0.08 percent. In these children, incidence of polyploidy was 80 percent [1000 times larger] .
Proponents of food irradiation have attempted to dismiss this study since only five individuals were involved, but mercifully no one has repeated this with greater numbers of children, especially since equivalent results were found when irradiated wheat was fed to monkeys and rats. In both these studies polyploidy was seen after several weeks of feeding and returned to normal about two months after feeding irradiated wheat was stopped. In summary, I would be hard put to find a group of better studies to demonstrate the mutagenic properties of irradiated wheat
In summary we feel the FDA has adopted scientifically indefensible criteria for assessing, and in their view, demonstrating, the safety of irradiated foods.
Treatment of food with ionizing radiation presents issues of food safety qualitatively unlike those posed by any other food processing method or food additive. The large amount of energy contained in ionising radiation provides the potential for exceedingly complex chemical transformation of food components including the production of mutagenic or carcinogenic substances which were not present or were present in far smaller amounts before irradiation. This potential far exceeds that of ordinary heat processing, microwave radiation, etc. At the same time, because the production of these "radiolytic products" takes place within the food itself, it is impossible to design a toxicological test in which animals are exposed to exaggerated doses of these products the chemical identity of which remains largely unknown. Thus toxicologists are limited to biological testing which is thousands of times less sensitive than the testing typically required of other chemical additives or pesticide residues.
In 1979, after years of controversy and false starts, radiation food processing was reevaluated by a specially appointed FDA committee, the BFIFC (Bureau of Foods Irradiated Foods Committee) They acknowledged that feeding whole irradiated foods to test animals, even after long periods of time, was completely inadequate to assess the carcinogenic potential of the radiolytic products present in those foods. As an alternative to direct biological testing they proposed acceptance of a theoretical calculation of the maximum concentration of radiolytic products present in irradiated food -- and made the extraordinary leap of faith that parts-per-million residues of unknown substances pose no risk when ingested by millions of people over their entire lives.
Subsequently an FDA task force reiterated the BFIFC recommendations and reported the results of an elaborate Review" of the available literature on the toxicological testing of irradiated foods - testing which they, as well as the BFIFC, agreed was inherently incapable of providing definitive evidence of the safety of irradiated food. The five studies which have been mentioned by others at this hearing provided, according to the Fen itself only the assurance that irradiated food is not wildly mutagenic and/or carcinogenic. The task force therefore justified its conditional approval of irradiation of fruits and vegetables with up to one hundred thousand rads, and spices with up to three million rads, on the same theoretical basis as proposed by the BFIFC.
Proponents of food irradiation commonly claim there are no studies in the scientific literature showing mutagenic or carcinogenic activity in irradiated foods or food components. In fact, as our own literature survey has shown, dozens of such studies exist, observed in a variety of biological systems, published by a variety of authors, in a variety of peer-reviewed scientific journals, over a period of twenty years.
In fact, a substantial number of studies can be found in the open scientific literature indicating the presence of known mutagens, carcinogens, or cytotoxic substances in focd or food components which have been irradiated. Furthermore, the radiation chemistry of foods is far from fully understood, as evidenced by a steady appearance in the literature of studies on new radiolytic products found in various irradiated foods (e.g. Simic and Jovanovic, 1986; and ^khlag et al, 1987) Many of these radiolytic products have not been individually tested for mutagenicity or carcinogenicity.
In short, the available scientific literature provides evidence to make a strong presumption of carcinogenicity in some if not all irradiated food. The question is one of quantifying the risk. Recently, the National Academy of Sciences (1987) identified twenty-three pesticides which are responsible for the vast majority of the total carcinogenic risk posed by the presence of pesticide residues in the U S food supply. Food irradiation would make essentially no contribution to the elimination of these pesticides since, of the twenty-three, several are herbicides or insecticides applied in the field, and the remainder are fungicides, whose replacement by irradiation is a highly dubious proposition. In fact irradiation of fruits and vegetables may well increase, rather than decrease, the requirement for post-harvest application of fungicide, because irradiated products are more susceptible to infection by colds and fungi. On the question of the use of ionizing radiation to inactivate salmonella in poultry, it is important to understand two points:
In summary, the continuing research effort by our organisation indicates clearly that recent and pending approvals of food irradiation processing by the FDA should be rescinded, and the same degree of caution now being expressed by several states and national agencies around the world be implemented on a federal level.