Junkfood Science: JFS Special: Eleven things you may not know about food irradiation

August 27, 2008

JFS Special: Eleven things you may not know about food irradiation

On Friday, the Food and Drug Administration published its final rule which will permit fresh and bagged iceberg lettuce and spinach to be irradiated to help protect consumers from the disease-causing bacteria behind the most common causes of foodborne illnesses, Salmonella and Escherichia coli 0157:H7. Food irradiation enables these susceptible vegetables to be safer to eat, while retain their nutrient value and slow spoilage, according to the FDA. While this was greeted as good news by most medical professionals and food scientists, almost immediately a flurry of fears and old myths resurfaced that had, or so most toxicologists thought, been put to rest more than a decade ago.

Fear is never helpful when you’re trying to make informed decisions for you and your family. Information is.

Dusting off fifty years of research and scientific expert reviews on food irradiation from forty countries — the sheer number of studies filling an entire file cabinet can’t be covered individually — let’s sum up the body of evidence behind the most common, and enduring, scares about food irradiation. We’ll start with the conspiracy theories.

Fact: Food irradiation is not a plot by the government to use up nuclear waste, cesium-137.

Helpful details: Cesium-137 isn’t used by any of the food irradiator facilities anywhere in North America. Cobalt-60 is used, which is specially made from natural cobalt at the Chalk River Laboratories of Atomic Energy of Canada Ltd. Cobalt-60 not a nuclear waste.

According to Dr. Elsa Murano of the Center for Food Safety and Dr. Peter Murano at the Center for Food Processing Technology, both with Iowa State University: “Food irradiation began as a result of the ‘Atoms for Peace’ program established by President Eisenhower in the early 1950s.” It was an effort to find peaceful, beneficial ways to utilize the advanced technological discoveries associated with atomic energy, not use up radioactive waste. The National Food Irradiation Program officially began in 1953.

Fact: Food irradiation does not creates nuclear waste or risk a nuclear disaster.

Helpful details: Cobalt-60 doesn’t produce neutrons that could activate materials or make them radioactive, nor can it start a fission chain reaction. A nuclear meltdown is not even possible, explains the American Nuclear Society.

Cobalt-60 doesn’t create radioactive waste. Very little cobalt 60 is needed at each radiator facility and can be used for about 15 to 20 years before the cobalt “pencils” are returned to Canada where they can be re-activated and reused or stored. Shipments are made in special hardened steel canisters that have been designed and tested to survive crashes without breaking. Cobalt is a solid, and even if somehow something should break, it will not spread through the environment, as the UW Food Irradiation Education Group explains.

According to the Canadian producer, if they’d decided to store all of the cobalt-60 they’d supplied to the world in 1988 (about 100 million curies) rather than recycle it, it could have been stored in a 1.25 cubic meter space (the size of a small desk).

Irradiation is a safe and carefully regulated and monitored technology. Facilities in the U.S. using gamma sources must be licensed by the U.S. Nuclear Regulatory Commission, must meet requirements of the Occupational Safety and Health Administration and the Environmental Protection Agency to ensure that workers and the environment will not be adversely affected in any way, and are subject to strict inspection control, according to the American Nuclear Society.

Cobalt-60 is also used in over 600 hospitals and medical radiation treatment centers and, after forty years and over a million isotope shipments, there has not been a single accident or radiation exposure to the public or environment, according to the Centers for Disease Control and Prevention.

Fact: Food irradiation does not make food radioactive.

Helpful information: Irradiated foods are not radioactive foods. From science class you may remember that gamma rays are the short high-energy waves at the upper end of the electromagnetic spectrum and are similar to ultraviolet light and microwaves. Food never touches any radioactive material during the process. Irradiated foods and their packaging are not made radioactive because most of the energy simply passes through the food, much like microwaves pass through food, leaving no residue, explains Joe Sebranek, Ph.D. with the Food Science and Human Nutrition Department of Iowa State University.

It’s also just like your teeth and bones are not radioactive after you have an X-ray.

The amount of radiation is measured using a unit called the Gray and low levels are used on food. Reviewing the evidence, international health and safety authorities have supported the safety of irradiation for all foods up to a dose level of 10,000 Gray, which is equivalent to the heat energy required to increase the temperature of water by 2.4ºC. While higher doses aren’t harmful, they can change the sensory qualities of foods. That’s why food technologists work to carefully balance the optimum dose — they want to use the least amount of radiation necessary to accomplish the objective, while minimizing the sensory effects on food. Clearly, it’s of no benefit to food producers to have food that doesn’t taste, smell or look good, and not all foods lend themselves to irradiation. Irradiation, for instance, isn’t used on liquid foods; so it makes the whites of eggs slightly thinner like an older egg and milk taste slightly different. But when used appropriately on solid foods, the irradiated food is indistinguishable, or even better with storage, than nonirradiated foods.

Three general dose applications are used in foods around the world:

Low-dose irradiation — up to 1,000 Gray (is used to inhibit sprouting; delay ripening; insect disinfestation; parasite inactivation).

Medium-dose irradiation — 1 to 10,000 Gray (reduces spoilage microorganisms and reduces or eliminates disease-causing microorganisms).

High-dose irradiation — above 10,000 Gray (can reduce microorganisms to the point of sterility).

Fact: Food irradiation has been extensively tested and shown safe.

Scares: The claims that may feel the most unsettling are those saying that food irradiation is new, untested and that the government is experimenting on the American public. According to Food & Water Watch, the FDA has approved food irradiation despite paltry and flawed safety data. The long list of dangers the organization describes sound so scary, it’s easy to feel they must know something you don’t: “Scientists have observed serious health problems in lab animals fed irradiated foods,” they say. “Those include premature death, cancer, tumors, stillbirths, mutations, organ damage, immune system failure and stunted growth. In one experiment, genetic damage was detected in young children who ate irradiated wheat. In some foods, irradiation forms chemicals known or suspected to cause cancer and birth defects.”

Helpful facts: Food irradiation has the longest history — more than 55 years — of intense scientific research and testing of any food technology in the world and found to not be harmful in any way. It may actually be surprising to learn how long food irradiation has been studied since the process was first patented for killing bacteria in food back in 1905.

“It was firmly concluded by a study conducted in Germany as far back as 1926 that irradiation did not produce any toxic factors in animal diets,” said the International Consultative Group on Food Irradiation [a joint World Health Organization Division of Nuclear Techniques in Food and Agriculture, UN Food and Agriculture Organization (FAO), and the International Atomic Energy Agency (IAEA), with scientific agencies from 40 countries]. Since then, countless hundreds of toxicological studies have been conducted in animal testing, including genetic studies, by scientists around the world. As the ICGFI explained:

FAO, IAEA and WHO convened a number of Joint Expert Committees on the Wholesomeness of Irradiated Foods in 1964, 1969, 1976 and 1980 as data became available to evaluate the safely for consumption of irradiated foods. These evaluations together with those carried out independently by national expert groups in Denmark, France, the Netherlands, Japan, the United Kingdom and the USA demonstrated no toxic effects as a result of consuming irradiated food. Another expert committee evaluated for the WHO in 1992 all literature and data which had been available since 1980; as a consequence, the previous findings were reconfirmed. During September 1997 a study group meeting was organised jointly by the WHO, FAO and IAEA to evaluate the wholesomeness of food treated by high dose irradiation. This group of experts concluded that doses greater than 10,000 Gray “will not lead to changes in the composition of the food that, from a toxicological point of view, would have an adverse effect on human health.”

During the 1980s, the FDA reviewed some 500 irradiation teratology and mutagenicity studies and found no adverse effects from low or high doses. “Over the last 20 year, millions of mice, rats, and other laboratory animals have been bred and reared exclusively on an irradiated diet,” said ICGFI. Even at doses of 50,000 Gray, studies in Austria, Australia, Canada, France, Germany, Japan, Switzerland, UK and USA have found that “no transmittable genetic defects — teratogenic or oncogenic — have been observed which could be attributed to the consumption of irradiated diets.”

As the CDC explained, the extensive safety studies have also been conducted on people, as well as well-controlled trials of animals in several different species fed all-irradiated food diets for several generations, and still found no evidence of adverse health effects. Sadly, no amount of evidence will be able to reassure some, and there will never be enough science to disprove a negative for them, but the body of the soundest evidence continues to not support worries of harm.

Fact: Irradiated food is not new.

Helpful information: Most disposable medical devices are sterilized using radiation, as are products such as tampons, baby bottles, cosmetics, food packages, juice cartons and wine corks. But foods and spices have been safely irradiated for decades, both in the United States and at least 38 major countries in the world.

According to the UN, several countries, including Belgium, France, Hungary, Japan, Netherlands and USSR are irradiating grains, potatoes, onions and other products on an industrial scale. Programs for irradiating potatoes, onions, and garlic were begun in Argentina, Bangladesh, Chile, China, Israel, Philippines and Thailand. China has sold irradiated apples since the early 1990s, for example.

Irradiation of wheat and wheat flour was approved in the U.S. in 1963, and since then irradiation has been expanded to include potatoes in 1964 to inhibit sprouting, spices and seasonings in 1986 for sterilization, dehydrated and dried foods in 1986 to control insects and improve storage, pork in 1985 to kill Trichina parasites, fresh fruits and vegetables in 1985, poultry in 1990 and 1992 to reduce bacterial pathogens, meats in 1997 and 2000 to control foodborne pathogens, and eggs in 2000, according to the CDC Division of Bacterial and Mycotic Diseases and the GAO. NASA has been irradiating foods for astronauts to consume in space since the 1970s. From Florida strawberries and onions to Hawaiian tropical fruits (papaya, rambutan, lycheese, cherimoya, irradiated produce has been safely eaten since the early 1990s.

As the 2000 GAO Congressional Report on the scientific studies on food irradiation said, about 97 million pounds of food are irradiated each year in the United States. The largest category are herbs, spices and seasonings, followed by fruits and vegetables and poultry. As toxicologist Dr. Kathryn E. Kelly noted, “we are all eating a lot of irradiated foods these days.” Never the less, only a fraction of the total amount of foods consumed that could be irradiated, is, noted the GAO.

Fact: Food irradiation helps prevent food waste and spoilage, reduce the need for chemical fumigants, and can help feed more of the world’s people.

Helpful information: According to the UN Food and Agriculture Organization, about 25% of all food produced worldwide is lost after harvesting because of insects, bacteria and rodents. “The use of irradiation alone as a preservation technique will not solve all the problems of post-harvest food losses,” explained the ICGFI, but it can play an important role in reducing food losses, as well as cut dependence on chemical pesticides.

“Many countries lose huge amounts of grain because of insect infestation, molds and premature germination,” reported the FAO. Sprouting, for example, is the major cause of losses for roots and tubers, which are important staples. These losses not only mean large financial losses for struggling farmers, but can mean more people can go hungry.

Many spoilage microorganisms, such as Pseudomonas spp are sensitive to irradiation and when irradiation is applied to poultry, for instance, not only is Salmonella eliminated, but most of the spoilage bacteria is, too. “This will double meat shelf-life, provided it is kept below 5ºC,” according to the ICGFI experts.

For highly perishable foods, food irradiation is proving not only highly desirable, but critical, said ICGFI. Low-dose irradiation can slow ripening and control fungal rot, such as in bananas, mangoes, papayas and strawberries. The fresher the food, the more effective irradiation is in improving shelf-life. Strawberries, which frequently spoil by Botrytis mold, can have a shelf-life of up to 14 days (stored at 10ºC), and mushrooms’ shelf-life doubles, with irradiation.

“The chief problem encountered in preservation of grains and grain products is insect infestation,” said ICGFI. Most of the pests of concern (beetles, moths, weevils and others) cause extensive damage during storage, but irradiation has proven an effective alternative to methyl bromide, the most widely-used fumigant, which is being phased out because of environmental concerns. The irradiation doses needed are low. Irradiation is now being used around the world to prevent losses by insects in stored grains, pulses, flour, cereals, coffee beans, dried fruits, dried nuts and other dried food products, including dried fish.

Contamination is a special burden whenever produce and spices are stored or dried. Until recently, most spices and herbs were fumigated to destroy contaminating microorganisms, according to the ICGFI. However, fumigants are increasingly being banned, such as the use of ethylene oxide prohibited by the European Union in 1991, and they also leave chemical residues on foods. Irradiation has been embraced as a more healthful, cleaner and environmentally-friendly alternative, said the ICGFI experts, “and its use results in cleaner, better quality herbs and spices compared to those fumigated with ethylene oxide.”

Irradiation has helped ensure safer international trade by preventing the spread of insect pests. Many countries require quarantine treatment of imported fruits, but these treatments are increasingly being banned, such as the use of ethylene dibromide. Irradiation has proven to be a very effective alternative to control fruit fly and other insect problems without chemical fumigants, and has been used in the U.S. since 1996.

Around the world, during times of the year when local produce is not available, in order to provide people with foods and staples, such as potatoes, onions, yams and other plant foods that sprout, long-term refrigeration is needed. But that’s costly, especially in warmer regions of the world. An alternative is chemical sprout inhibitors, such as maleic hydrazide, propham or chloropropham, but these don’t work well under tropical conditions and can leave residues on the produce, said the ICGFI. Very low irradiation inhibits sprouting on these foods without leaving residues, while allowing them to be stored at higher temperatures and enable them to reach and feed more people.

Facts: Food irradiation can save lives and help prevent miscarriages, congenital toxoplasmosis and other catastrophic illnesses.

Helpful details: Amidst fears, the message that always seems to get lost is the benefits of technological developments and how many lives could be saved and how many devastating health problems that could be prevented. As Dr. Dennis G. Maki, M.D., professor of medicine at the University of Wisconsin School of Medicine and Public Health in Madison, wrote: “Unfortunately, because of widespread lack of understanding of the risks and sequelae of foodborne disease and the effectiveness and safety of irradiation, [food irradiation] has not yet achieved widespread acceptance.”

This past week’s FDA announcement comes as Tulsa mourns the loss of a 26-year old man from E.coli foodborne illness and Canadian health officials announce that the death toll from listeria in processed meats has reached twelve.

Looking at the larger picture, doctors and scientists weigh the reality of the benefits with potentials for harm. As toxicologist Dr. Kathryn E. Kelly noted, we know thousands of people get sick from farm manure and pathogens found in nature, and even die from foodborne illness each year, but “we can't point to a case of anyone who has ever gotten sick from eating irradiated foods.”

The CDC has estimated that irradiation of high-risk foods could prevent up to a million cases of bacterial foodborne disease that result in the hospitalization of more than 50,000 persons and kill many hundreds each year in North America.

Dr. Robert V. Tauxe, medical epidemiologist and chief of the Foodborne and Diarrheal Diseases at the CDC, brought clarity to those health benefits in a 2001 paper where he illustrated the effects if half of just meat and poultry would be irradiated in our country. He estimated 8,500 hospitalizations would be prevented; along with 881,625 cases of foodborne illnesses just from the E. coli, Campylobacter, Salmonella, Listeria and Toxoplasma. Additionally, 6,660 catastrophic illnesses would be prevented — and these can’t be taken lightly — at least 250 cases of hemolytic uremic syndrome, 250 cases of group B strep, 6,000 cases of reactive arthropathy, 60 miscarriages, and up to 1,000 cases of congenital toxoplasmosis.

Professor Dennis Olson, director of Iowa State University’s Linear Accelerator research facility, and food irradiation researcher observed: “If we treat all of the lettuce and spinach, then there's going to be a very rare instance of exposure to illness-causing microorganisms.”

“This is especially important for at-risk populations immune-compromised folks, pregnant women, children under the age of eight, and elderly,” he explained. “These people are at high risk for food-borne illness and it may be useful to feed them greens that have been irradiated, for that last margin of safety.”

What many consumers may not realize is that irradiated foods are actually preferable for significant numbers of the population, precisely for their safety benefits. As the GAO report noted, irradiated foods are specifically purchased by healthcare and food service establishments, from nursing homes and hospital, to school systems and restaurant chains, to help ensure the safety of people with weakened immune systems whose lives could be jeopardized by a foodborne illness, or to prevent widespread outbreaks. For cancer patients, fragile elderly in nursing homes, bariatric surgery survivors, HIV/AIDS patients and other people with suppressed immune systems or compromised gastrointestinal systems, foodborne illnesses can be life threatening. Medical professionals often advise them to avoid fresh produce and raw and organic foods — reminding them that even the most wholesome foods from nature isn’t sterile. Irradiated foods have enabled these vulnerable patients to be able to enjoy fresh foods more safely.

Another cost of foodborne illness are the financial hardships. Not only do foodborne illnesses pose a serious threat to human health, they are an important cause of reduced economic productivity, according to studies by the CDC in the early 1990's. They showed that foodborne diseases caused by pathogenic bacteria, such as Salmonella and Campylobacter and by Trichinae and other parasites, claim an estimated 9,000 lives annually and cause 24- to 81-million cases of diarrheal disease in the United States alone. Economic losses associated with these diseases were estimated at between $6.5 billion and $33 billion.

The idea that we don’t need irradiated foods isn’t supported by evidence.

Facts: Food irradiation can be an important aspect of food safety procedures and an effective critical control point in the Hazard Analysis and Critical Control Points (HACCP) system.

Helpful information: All food, no matter how it’s grown, is susceptible to air- and soilborne bacteria, fungi and insects. While, undeniably, we have the safest food supply in the history of our country, food scientists are continually working to make it safer. Since 2004, there’s been a 43% decrease in the E.coli contamination of ground beef samples tested by the USDA, according to Dr. Maki, writing in the New England Journal of Medicine. This decrease has followed intensified federal regulatory efforts to improve food-safety systems and microbiological testing by producers.

But achieving further improvements is unlikely if we continue to rely solely on our current strategies, he noted, and don’t accept food irradiation on a wider scale.

Fresh produce, like lettuces and spinach, is especially challenging, because no amount of washing reliably eliminates the risk of contamination naturally found on fresh produce plucked from the soil, explained Dr. Maki. Unlike meats, which can be cooked to kill pathogens, most fresh produce is eaten raw and doesn’t have a “kill step,” to ensure safety, added the Institute of Food Technology.

With more than four million tons of lettuce, spinach and sprouts eaten in North America every year fresh and uncooked, said Dr. Maki, “irradiation can greatly reduce the incidence of all bacterial foodborne disease and save hundreds of lives each year.”

Recent E.coli 0157:H7 and salmonella outbreaks, and recalls of spinach, lettuce, and other leafy greens in 2006 and 2007, have raised public concerns of produce safety. “In 2006, there were an estimated 50 billion servings of green, leafy salads served in this country, and there were approximately 1,200 people made ill,” said Sam Beattie, Extension food safety specialist and an assistant professor of food science and human nutrition at Iowa State University. While the risks of food-borne illness from produce are already extremely low, he said, irradiation is one more tool to ensure safety.

As the Institute of Food Technology notes, food irradiation has been shown effective on the bacterial pathogens on fresh produce that most make people sick, such as E.coli O157:H7, Salmonella, and Listeria monocytogenes, and the pathogens that make food spoil. Irradiation that results in a 1-log reduction in bacterial pathogens can be achieved at the lowest levels of radiation. “The majority of serious foodborne illnesses resulting in hospitalizations and deaths (60% and 72%, respectively) come from bacterial pathogens,” said the IFT.

Meaning, irradiation is most effective for the elimination of the most serious safety threats for consumers.

Fact: Food irradiation can never replace existing food safety and sanitation practices, or be used to pawn bad food off onto consumers.

Scares: Trying to convince us that food irradiation could be used to hide disgusting, filthy food and sell us rotted, poor quality or dangerous food may sound frightening, but defy the scientific reality of how food irradiation works. But we hear horror tales about slaughterhouses and food processing plants, filled with unsavory depictions of feces, urine and pus.

Helpful facts:
Food processes such as heating, freezing, chemical or fumigation treatment, and irradiation are not intended as substitutes for good hygienic practices, explain the ICGFI experts. “Both at the national and international levels, good manufacturing practices (GMPs) govern the handling of specific foods and food products.” Clean practices must be followed in the preparation of food for irradiation. In fact, irradiation requires a stricter adherence to GMP in order for the product to be irradiated, ICGFI pointed out.

“Irradiation is not a short cut that means food hygiene efforts can be relaxed,” explains the CDC Division of Bacterial and Mycotic Diseases. “Many steps need to be taken from farm to table to make sure that our food supply is clean and safe. Irradiation is a major step forward, but it does not replace other important efforts, including efforts to improve sanitation on the farm and in the food processing plant.”

These assurances are not simply government or corporate rhetoric, but because of how irradiation works and how irradiation doses are calculated. “For irradiation to be effective, the food that is to be irradiated already needs to be clean,” explains the CDC. It won’t work effectively when food is highly contaminated. Also, “the more initial contamination there is, the higher dose of irradiation it would take to eliminate possible pathogens,” which means the more the taste and quality of the food would be affected. And then, no one would want to eat it.

In determining the amount of irradiation needed to kill 99.9% of the pathogens on the food, explains the CDC, food scientists measure D-values for that disease organism and how many organisms are present in the food. The, the irradiation technician can determine how much irradiation it will take to kill all of the pathogens present. They want to use the least amount of irradiation possible, not only to conserve costs, but to minimize any sensory effects on the food.

“Actually, combining irradiation with increased sanitation is advantageous because less contamination means lower doses of irradiation would be needed, decreasing the chance of changes in taste or smell of a product,” explained Dr. Robert V. Tauxe, medical epidemiologist and chief of the Foodborne and Diarrheal Diseases at the Centers for Disease Control and Prevention, Atlanta, Georgia, in a 2001 issue of Emerging Infectious Diseases.

It is impossible for irradiation to be used to pass along bad food to consumers, as many might fear, because irradiation does not enhance the quality of food, but only helps to make it safer. That means, if it wasn’t fresh or good tasting before treatment, it won’t be afterwards. Repeated studies have confirmed that irradiation cannot mask off flavors or odors of spoiled products.

But irradiation does enable farmers to let produce fully ripen to its peak flavors and nutritional value before being irradiated to help it retain its best qualities while enroute to market or storage. Farmers aren’t left to pick produce underripened and firm to help it withstand the trip or last long enough to be consumed. The quality of irradiated foods can quickly surpass nonirradiated foods with storage.

Doctors Peter and Elsa Murano, as food microbiology researchers at Texas A&M University, conducted multiple studies to evaluate the sensory appeal of irradiated foods and found that freshness, color, flavor, texture and acceptability are not significantly different from nonirradiated foods. In fact, “the only significant difference was the irradiated samples being rated as more tender and juicy than the unirradiated samples.”

Fact: Food irradiation has minimal effects on the nutritional quality and wholesomeness of foods.

Helpful information: Some of the most interesting findings of research on irradiated foods are on the nutrients. Irradiation is sometimes called cold pasteurization, said the ICGFI, because it does much the same thing as heat pasteurization, but without increasing the food’s temperature and leaves the food closer to its natural, fresh and unprocessed state. In contrast, chemical safety treatments can leave residues, and heating changes its texture, color and flavor and, well, cooks it.

Because irradiation at the doses used on food [don’t be fooled by studies that try to nuke foods beyond edibility, attempting to show how irradiation can be harmful] doesn’t raise the temperature of the food being processed hardly at all, nutrient losses are minimal, too. In fact, they’re largely less than the normal losses that occur with other methods of food preservation, such as drying, canning or heat pasteurization, or during cold storage. As the GAO review of the research explained, the main components of food — carbohydrates, protein and fats — change little during irradiation. “Vitamin loss corresponds to that in foods that are cooked, canned or held in cold storage” — all of which are perfectly nutritious.

As the IFT explains, vitamin B and C are the most sensitive to heat, yet, for example, studies have found no significant differences in the vitamin C content of irradiated and nonirradiated oranges with storage. The marginal losses of vitamins with irradiation are not clinically meaningful or to the extent that it would result in any adverse effect on the nutritional status of individuals or populations, said the FAO, IAEA and WHO. We get vitamins from a wide range of foods in our diet. The National Health and Nutrition Examination Survey, for instance, found negligible losses for thiamin, riboflavin and niacin in meats ranging from 0.01% to 1.5%.

“Irradiation can reduce ascorbic acid (vitamin C) in some vegetables, but the decrease is generally insignificant, given the natural variation observed in fresh produce, and does not exceed the decrease seen during storage,” reported the IFT. “Irradiation converts ascorbic acid to dehydroascorbic acid, both of which exhibit biological activity and are readily interconvertible.” And, interestingly, irradiation can also increase the phenolic content of some produce, meaning irradiation increases its antioxidant capacity.

“Many concerns about irradiation harken back to earlier objections to pasteurization and retort canning,” said Dr. Tauxe.

Fact: Food irradiation does not create dangerous cancer-causing compounds and eating it has not been shown to cause cancer.

Scares: Even a hint of the Big C can manipulate and scare the willies out of us. In addition to cancer fears raised by Food & Water Watch, the nonprofit activist group, Cancer Prevention Coalition has continued to report in press releases that irradiation forms “chemicals that are known or suspected to cause cancer and birth defects... Dozens of experiments dating to the 1950s have revealed a wide range of serious health problems in animals fed irradiated food.” According to Samuel Epstein, M.D., the group’s chairman and emeritus professor of environmental medicine at the University of Illinois' School of Public Health: “Every man, woman and child who takes a bite of irradiated food increases their chance of getting cancer. It is no exaggeration to say that our government has turned the American people into guinea pigs.”

Helpful research: As the ICGFI and GAO report have noted, over half a century of international scientific research — on multiple species, humans and multi-generational — has failed to support concerns of irradiated foods or that they cause cancer. The irradiation process produces very little chemical change in food, none of which have been found to be harmful or risky. As they explain, the substances produced by irradiation are like those in cooked food.

Don’t let words scare you into fearing that irradiation causes uniquely dangerous substances to be created. Radiolytic does not mean radioactive or toxic in some way. It simply means that these substances are produced by irradiation, in the same way that thermolytic products are produced by cooking and heat processing. As these scientific experts explain, most of these radiolytic products are the familiar substances found naturally in nonirradiated foods or that are also produced in foods when they’re cooked. “The safety of these radiolytic products has been examined very critically, and no evidence of their harmfulness has ever been found.” The FDA has estimated radiolytic compounds are formed in amounts less than 3 parts per million.

As Dr. Murano at the FDA Center for Food Safety said, “no radiolytic products have been found in irradiated foods that have not been found in much greater amounts in food exposed to ordinary cooking.”

All forms of food preparation, including cooking, steaming, canning, roasting, pasteurization and freezing, create small amounts of free radicals. Free radicals are even produced in the natural ripening of fruits and vegetables, but no one would argue we shouldn’t consume fresh fruits and vegetables. But free radicals are also used to frighten us into fearing irradiation could be dangerous. ICFGI puts these concerns to rest by explaining:

Free radicals disappear by reacting with each other in the presence of liquids, such as saliva in the mouth. Consequently, their ingestion does not create any toxicological or other harmful effects. This has been confirmed by a long-term laboratory study in which animals were fed a very dry milk powder irradiated at 45 kilogray, more than four times the maximum approved dose for food irradiation. No mutagenic effects were noted and no tumours were formed. No toxic effects were apparent in the animals over nine successive generations. Similarly, a toast of bread (unirradiated), which actually contains more free radicals than very dry foods that have been irradiated, can be expected to be harmless.

Radiation kills only rapidly growing cells — those of insects or pathogenic bacteria — but there is little effect on the food itself because the cells in food are not multiplying. But fears have circulated since the 1970s that eating irradiated foods can cause abnormal chromosomes [DNA damage] and cancer. The source of this fear is a group of scientists from the National Institute of Nutrition (NIN) in Hyderabad, East India, who cited studies on rodents and monkeys, and one study on 15 severely malnourished children hospitalized for kwashiorkor, in which five children were fed bread made with freshly-irradiated wheat for six weeks. It’s worth taking a look at the source of this fear.

According to this study, published in 1975 in the American Journal of Clinical Nutrition, these children were all so severely malnourished, “all of them had severe growth retardation edema of the lower extremities, mental apathy and hypoalbuminemia—levels of serum albumin being below 2 g/I00 ml.” While there were no differences among these children and the controls with regard to chromosomal aberrations, the authors reported finding more polyploid and abnormal cells. One notation made by the authors, which I’ve never seen publicly pointed out, said: “Viral infections and administration of cytotoxic drugs may be associated with the presence of polyploid cells, its significance may perhaps not be the same as that of polyploid cells ‘induced by the ingestion of irradiated wheat.’” [But their report failed to note which of the hospitalized children had received medications, and the intervention-control groups had not been randomized.]

Because this 30-year old claim of chromosomal damage continues to circulate, it might be helpful to learn what international scientists and research have concluded, after countless researchers tried to replicate this finding — a finding which has only been reported from that single source. As the International Consultative Group on Food Irradiation reported, no other researchers have ever been able to replicate the NIN finding, or find any mutagenic effect from irradiated wheat, writing:

Can eating irradiated food cause development of abnormal chromosomes? NO. The issue of abnormal chromosomes as a result of eating irradiated food has been more sensationalised than any other. The claims focus on the incidence of polyploidy, which is alleged to result from consumption of products made from wheat immediately after irradiation. Polyploidy means the occurrence of cells containing twice or more the number of chromosomes. Human cells normally have 46 chromosomes. If they are polyploid they could have 92 or even 138 chromosomes. The incidence of polyploid cells is naturally occurring and varies among individuals, and even in one individual from day to day. It can also vary from organ to organ within one individual.

The biological significance of polyploidy is unknown. When undertaking studies on polyploidy, it is important that many thousands of cells are counted in order to see the effect of a treatment. As polyploid cells are rare, it is essential that enough cells are observed before any valid conclusions can be reached. It can also be extremely difficult to recognise polyploid cells; if normal (diploid) cells happen to be superimposed on the microscope slide they look very much like one polyploid cell.

Media reports have frequently cited results published in the mid-1970s by a group of scientists from the National Institute of Nutrition in Hyderabad, India.... When the report is examined more closely, among other shortcomings, it is found that only 100 cells from each of the five children in each group were counted — an incredibly small sample upon which to base any conclusion. In addition, although the results in each group were averaged, there is no indication of the actual incidence in each child. No polyploidy at all was seen when wheat was irradiated and stored for 12 weeks before consumption.

A number of institutions in India and elsewhere have tried to reproduce the results found at NIN based on information made available to them. Some used absorbed radiation doses as high as 45,000 Gray...showed no effect from consuming the irradiated wheat. None of the studies carried out came up with results similar to those found at NIN.

Even the Indian government appointed a committee of experts to investigate the reasons for the discrepancy between the results reported by the researchers in Hyderabad, and, according to ICGFI, the Committee was “very critical of the work of the Hyderbad authors and concluded that the available data failed to demonstrate any mutagenic potential of irradiated wheat.” Even national scientific committees and independent researchers in Australia, Canada, Denmark, France, the United Kingdom and the USA, they reported, have evaluated the alleged incidence of polyploidy and concluded the data doesn’t support an increased polyploidy. Finally:

In 1988 D. MacPhee and W. Hall, advisers to an Australian Parliamentary Committee Inquiry into the use of ionizing radiation, examined the NIN results. They concluded that the inability of other researchers to replicate the NIN results casts doubts upon the reliability of the NIN conclusions; that polyploidy is a poor measure of genetic damage; and that "major biological implausibilities" exist in the chain of occurrences "which allegedly links the consumption of irradiated food with the occurrence of genetic events".

Of course, food irradiation is not a cure-all or the only technique used by food scientists and producers to help ensure the safety of our food, nor does it absolve us from our role of careful food handling in our home kitchens, but it can be a valuable additional tool for helping us keep our families safe.

Most importantly, knowledge can help us to make more informed decisions.

© 2008 Sandy Szwarc. All rights reserved.

For more information:

Food Irradiation from the Centers for Disease Control and Prevention Division of Bacterial and Mycotic Diseases

Facts about Food Irradiation from the International Consultative Group on Food Irradiation

Food Irradiation — Available Research Indicates That Benefits Outweigh Risks from GAO report to Congress

Bookmark and Share