Is food irradiation not similar to microwaving?
Food irradiation is sometimes incorrectly compared to microwaving. The energy particles in a gamma ray used in food irradiation are up to 10 billion times more energetic than microwaves, making this a vastly different technology.
Is irradiation the same as x-rays or radiation from the sun?
A chest x-ray gives about 0.01 rad of energy. The average dose of radiation from background radiation (radiation due to cosmic rays and natural radioactivity such as radon in rocks) annually is 0.1 rad. On the other hand, the dose of radiation from gamma rays applied to food during irradiation is 100,000-1 million rads (1-10 kGy). The amount of radiation being applied to food during irradiation is therefore massive, 10 million to 100 million times the dose of a chest x-ray.
How long will the radioactive Cobalt-60 being used in food irradiation facilities exist in our environment?
A radioactive isotope is generally considered to be hazardous for a period of 10-20 times its half life (the time it takes for half the nuclei of the radioactive material to undergo radioactive decay, and hence for the radioactivity of the material to be reduced by half). Cobalt-60 has a half-life of about 5 years which means it remains radioactive for 50-100 years. As the material is always disintegrating the cobalt-60 needs ongoing replacement. About 12% of the cobalt-60 used in irradiation facilities needs to be replaced yearly. This spent cobalt-60 and other nuclear waste needs to be stored. Right now we have tens of thousands of tonnes of spent nuclear fuel in storage, in Canada alone. Cobalt-60 is purposely produced in CANDU reactors from non-radioactive cobalt-59 for the purpose of irradiation. An irradiation facility requires huge amounts of radioactive material (e.g., 1-10 million curies), up to a 1,000 times more than a medical hospital irradiation facility. Food irradiation facilities will increase the total load of radioactive waste in the environment. Food irradiation creates nuclear waste just like a nuclear power plant.
What risks does food irradiation present because it is a nuclear technology?
The use of radioactive materials, even in small amounts, naturally raises concerns about the safety of the environment. I believe we are all well aware that nuclear waste storage is a problem in Canada, with no immediate solution in sight. With many food irradiation facilities, spread across Canada, located in your community, the amount of radioactive waste will escalate. There will be increased transport of radioactive material, which increases the risk of an accident - no matter what precautions are taken, there is never a guarantee that an accident or terrorist event will not result in a radioactive spill. All nuclear facilities have inherent occupational risks for the workers and those living near the facility; accidents at food irradiation facilities have already been documented.
Why not use X-rays or accelerated electron beams instead of nuclear material in irradiation facilities?
They do not have the same penetrating ability as gamma rays from nuclear material so have limited commercial usefulness. They will not penetrate much more than 2-4 cm, for example they could only be used with small particles of food, such as wheat grains. Accelerated electron beams produce some unwanted heat in the food, which also limits their commercial usefulness.
Are irradiated foods labeled so that consumers can choose to not buy them?
Yes and no. Foods containing ingredients that are irradiated and comprise more than 10% of the product are required to be labelled with a flower-like symbol (that imparts a seal of approval) and with wording implying irradiation. However, ingredients constituting less than 10% of a product are not required to be labelled, even if there are numerous irradiated ingredients in the product. Another major labelling concern is that there is no requirement to label any irradiated foods served in restaurants, hospitals and schools. If hamburger is irradiated in Canada and sold exclusively to fast-food restaurant chains, Canadians will be consuming irradiated food without knowing it, since irradiated hamburgers will not be labelled.
Is irradiated food safe?
Irradiated food has not been studied in the same way as other food chemicals or food additives. Well over a thousand food irradiation safety studies have been done and none have proven food irradiation to be safe. The reason being is that none of the studies utilized an acceptable safety factor. If a company wants to introduce a new food additive they are required to test that additive using what is called a "100-fold safety factor"; considered to be the standard. This means that the food additive will be fed to test animals over a period of time, generally two years or more, starting first with small amounts of the food additive then increasing to larger amounts. They would determine the highest dose of the additive which results in no toxic effects. This level is then divided by a safety factor of 100 to obtain the maximum dose level allowed in food. For food irradiation safety studies to mimic the 100-fold safety factor, that would mean increasing the dose of irradiation 100 times. This would basically ruin the taste and consistency of the food making the study unfeasible. So, in fact, food irradiation safety studies simply tested food that had been irradiated at the level that the nuclear industry had chosen as being commercially convenient; not based on safety. Also, most of the studies were conducted for only a few weeks or months, yet some cancers have latency periods of many years, and mutation effects may not show up for several generations.
What is really worrisome, is that in spite of no safety factor, and in spite of studies often being too short, some studies have actually shown adverse effects. Unhealthy chemicals have been found in larger amounts in irradiated foods, such as, lipid peroxides and benzene. Some studies have shown reduced survival rates and decreased immunity in test animals. Other studies on test animals, house flies, bacteria and plant and human cell tissues, have shown cell toxicity, cancer or mutations.
Calling for further research will not resolve our consistent doubts about the safety of irradiated food. One of the greatest concerns is the unknown effect of feeding irradiated foods to people over long period of time.
Can irradiation get rid off food poisoning from E.coli and Salmonella?
First of all its important to recognize that there are many causes of food poisoning, and irradiating some food stuffs is not going to prevent contamination from other sources, nor cross-contamination of the irradiated food. Only good hygiene can prevent this.
Having said that, there are real concerns about bacteria in irradiated food. Commercial irradiation doses proposed for meat and poultry can kill a large number of bacteria, but does not guarantee that all bacteria will be killed, especially the more pathogenic ones. E.coli and Salmonella have been shown to survive irradiation doses 50-100% higher than commercial doses. Various factors affect whether or not there is an even or complete kill of bacteria. For example, kill can be inconsistent due to inconsistencies in the dose. The actual dose depends on the rate at which food passes the radiation source; the radioactivity of the cobalt-60 rods (cobalt-60 is continually disintegrating, so the rods need to be rearranged and replaced on an ongoing basis to maintain some modicum of consistency in dosages); the chemical composition and physical state of the food (for example frozen food requires a higher dose); the size and shape of the food; and the more contaminated the food, the higher the dose is needed to complete kill (yet higher doses would result in adverse smell and taste changes to the food). Even if a small number of pathogenic bacteria survive, they can go on to grow and reproduce after irradiation. Growth is especially effective after irradiation because many other bacteria have been killed off so competition is less. For some bacteria such as E.coli 0157:H7, even a small number of bacteria can be dangerous. A final consideration is that irradiation has been shown to increase the rate of bacterial or viral mutations, which could lead to "super germs" that are more resistant to irradiation, and will lead to even greater problems for humans down the road.
Why is raw ground beef so likely to be contaminated?
Cattle are known to be the largest reservoir of E.coli 0157:H7 and they carry the bacteria in their lower intestines. When the cattle are slaughtered the intestines can be split open and the bacteria are spread onto the carcass itself. This means that a piece of steak or a roast can carry these bacteria, but only on the outside. When you cook that steak or roast, the outside part carrying the bacteria is cooked the most, so the bacteria are killed. When raw contaminated meat is ground, the bacteria is distributed throughout the meat. So you now have bacteria on the outside as well as the inside of a raw ground meat patty. Thick, frozen hamburgers are a particular concern since its difficult to cook the inside without burning the outside. It is important to have thinner hamburgers, and if the hamburgers are frozen to thaw them in the fridge prior to cooking, and to make sure there is NO pink showing after cooking.
What are the alternatives to food irradiation in preventing food poisoning?
Alternatives with better outcomes exist. They are less expensive and carry less or no risk to consumers and the environment compared to food irradiation. The prevention of food poisoning lies in good animal husbandry, in reducing pollution of our waterways and water supplies, in clean and careful food handling, and preventive hygiene.
The prevention of food poisoning is like a chain with many links that need documentation, control and management. The following are the 4 weakest links in the chain:
- Link 1: The farm. We need to assess the living conditions of cattle, poultry and other animals raised for human consumption. We know that a healthy human has less disease and the same goes for animals. For example, poultry farms need adequate spacing of pens, adequate air ventilation, and no contamination of feces into their water and food supply. For cattle; a manure management program is especially important. This would include reducing pollution with animal waste of our waterways, wells and water supplies from the farm operations. An example of research in cattle management is a possible vaccine against E. coli 0157:H7 given to cattle, and it is now at the field trial level. Research is also developing a bacterophage preparation (a mixture of viruses) that infect and kill E.coli at its origin - the intestine of cattle. At the farm we also need to ensure that workers or young children in direct contact with livestock wash thoroughly after contact.
- Link 2: The slaughter house. There are numerous hazard analysis points that have been clearly identified by the industry and government. These need to be carefully monitored, not only by industry, but also more tightly by the Food Inspection Agency. An example of a critical hazard point is when the animal is slaughtered, that the intestine contents don't contact the rest of the carcass. To date, its only by choice that some slaughter houses mandate the spraying of carcasses with antimicrobial sprays, or subjecting the carcasses to steam in a chamber, followed by rapid chilling.
- Link 3: Storing, transporting and packaging. Tight hygiene is needed to prevent contamination and cross-contamination during these steps. We need better and faster methods of detecting E. coli and other organisms at the processing and retail level, to prevent new areas of possible contamination, and to identify sources of contamination.
- Link 4: The consumer or restaurant. At this link in the chain, food poisoning can be avoided by following what I call the FIVE C's; which I believe should be taught in Kindergarten and reinforced at every grade level.
- Cleanliness: including, hand washing and cleaning of utensils and counters. All raw foods should be washed, and milk pasteurized.
- Chilling: keeping cold foods cold, through adequate refrigeration or freezing.
- Cooking: keeping hot foods hot, and cooking foods such as chicken and hamburgers until there is no pink showing.
- Avoiding Cross-Contamination, by making sure you don't put your well-cooked hamburger on the same plate that held the raw meat.
As a dietitian what concerns do you have about the nutritional quality of irradiated food?
All food processing, including irradiation, results in some nutrient loss. Food irradiation has been shown to result in losses of fat-soluble vitamins, some of the B vitamins, vitamin C, and nutrients such as fat. Loss of nutrition generally increases in foods that contain higher amounts of water and as radiation dose increases.
One of the main concerns with food irradiation is that it is going to be added along with other food processes. So for example, when a food is frozen there is some loss of nutrients, but if it is irradiated first, then stored, then frozen, there is much greater loss of nutrients.
One particular nutrient which is affected is fat. Irradiation breaks the bonds of fats, including omega-3 fatty acids, and given their importance in protecting the heart, any losses are significant. Irradiation also decreases vitamin E, an antioxidant that protects the good fats, the polyunsaturated fats, which protect the heart.
Fresh produce is a dietitian's first choice, and where fresh food is not available we look to preserving produce that is as fresh as possible. We want the fruit or meat that is canned to be fresh. We don't want to can fruit that was picked a week ago or meat that was slaughtered a week ago, then irradiated, then canned.
Isn't irradiation safer than using chemicals?
It is true that pesticides, herbicides and fungicides carry varying levels of risk to humans and the environment. However, this does not mean we should overlook the human and environmental risks of food irradiation. There are some really positive trends happening in some sectors of agriculture, for example, integrated pest management which reduces the use of agricultural chemicals is an important step forward. The costs of having a safe food supply are initially high but because they are environmentally sustainable they will prove far more beneficial to the public in the long term.
It is important to note that irradiation will not reduce the amount of fungicides, pesticides and herbicides used during the growing period. The most likely chemical reduction would come from reduced fumigation of fruits and vegetables. Yet, fruits and vegetables are very sensitive to irradiation (they break down easily following irradiation), so it is not a process likely to be used with these foods extensively. Some studies have suggested that irradiation may increase the use of chemical additives, because irradiation might be combined with additives such as sodium nitrite to improve bacteria kill. Some new additives may be added to offset the bad odours or other organoleptic effects from irradiation.
What are the real financial costs of food irradiation?
A food irradiation facility, depending on type and size, will cost from $2 million to over $10 million for a larger facility, as calculated back in 1990. These costs don't take into account transporting the foods large distances to and from centralized irradiators, the cost of the land, the cost of the initial cobalt-60 (which can add another million dollars), the cost of ongoing cobalt-60 replacement, costs of storage of radioactive material, disposal, and radioactive spill clean up, worker safety training, and government regulation of facilities. Any food irradiation facility using nuclear material will require special containment and storage units and precautions. Cobalt-60 is always "ON" and that means irradiation facilities need to be operated 24 hours a day, every day of the year, for maximum efficiency.
An unanswered question is what might be the cost of adverse health effects in the general population following long-term consumption of irradiated foods?
Why is food irradiation such a polarized issue?
It seems that for every person or organization that is supporting food irradiation you can find someone or some group who is opposing it. For example the World Health Organization has given food irradiation the green light but the International Organization of Consumers' Unions opposes it. The American and Canadian Medical Association took stands in the 1980's supporting food irradiation with some restrictions yet the British Medical Association opposed food irradiation. Certainly some of the proponents have a vested interest, such as those involved in the nuclear industry, given that much of food irradiation is a nuclear technology. However, politics aside, the cattle, hog and poultry industries are recognizing the need to improve the safety of their meat and to reduce water contamination. But in our anxiousness to find solutions we must be careful to not go backwards and create another, larger problem.
The Canadian Government has played an instrumental role in food irradiation research and promotion - and we have yet to see any benefits. Most consumers are still following their gut reaction and saying "we don't want it", yet the government funding continues.
Will food irradiation help feed the poor nations in the world?
Food irradiation will not relieve the needs of hungry people, but will introduce more economic, environmental and health problems. Food irradiation is siphoning off research money that would be better spent on non-hazardous, environmentally safe alternatives. Food irradiation is inappropriate for developing nations, where the Canadian government is actually encouraging the purchase of food irradiators. These countries do not have the infrastructure for such a high technology and expensive industry, and besides, it won't improve the consumers' food buying power or the quality of their food. In spite of reassurances, once irradiators are sold to other countries, Canada cannot enforce its standards of environmental and occupational safety regarding the handling of radioactive material, nor regarding the potential for terrorism.
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