Food irradiation: Wikis


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The Radura logo, used to show a food has been treated with ionizing radiation.

Food irradiation is the process of exposing food to ionizing radiation[1] to destroy microorganisms, bacteria, viruses, or insects that might be present in the food. Further applications include sprout inhibition, delay of ripening, increase of juice yield, and improvement of re-hydration. Irradiation is a more general term of deliberate exposure of materials to radiation to achieve a technical goal (in this context "ionizing radiation" is implied). As such it is also used on non-food items, such as medical hardware, plastics, tubes for gas-pipelines, hoses for floor-heating, shrink-foils for food packaging, automobile parts, wires and cables (isolation), tires, and even gemstones. Compared to the amount of food irradiated, the volume of those every-day applications is huge but not noticed by the consumer.

The genuine effect of processing food by ionizing radiation involves damage to DNA, the basic genetic information for life. Microorganisms can no longer proliferate and continue their malignant or pathogenic activities. Spoilage-causing micro-organisms cannot continue their activities. Insects do not survive, or become incapable of proliferation. Plants cannot continue the natural ripening or aging process.[1]

The specialty of processing food by ionizing radiation is that the energy density per atomic transition is very high; it can cleave molecules and induce ionization (hence the name), which is not achieved by mere heating. This is the reason for both new effects and new concerns. The treatment of solid food by ionizing radiation can provide an effect similar to heat pasteurization of liquids, such as milk. However, the use of the term "cold pasteurization" to describe irradiated foods is controversial, since pasteurization and irradiation are fundamentally different processes.

Food irradiation is currently permitted by over 40 countries, and the volume of food so treated is estimated to exceed 500,000 metric tons annually world wide.[2][3][4] [5]


Processing of food by ionizing radiation

By irradiating food, depending on the dose, some or all of the harmful bacteria and other pathogens present are killed. This prolongs the shelf-life of the food in cases where microbial spoilage is the limiting factor. Some foods, e.g., herbs and spices, are irradiated at sufficient doses (five kilograys or more) to reduce the microbial counts by several orders of magnitude; such ingredients will not carry over spoilage or pathogen microorganisms into the final product. It has also been shown that irradiation can delay the ripening of fruits or the sprouting of vegetables.[1]

Furthermore, insect pests can be sterilized (be made incapable of proliferation) using irradiation at relatively low doses.[6] In consequence, the United States Department of Agriculture (USDA) has approved the use of low-level irradiation as an alternative treatment to pesticides for fruits and vegetables that are considered hosts to a number of insect pests, including fruit flies and seed weevils; the U.S. Food and Drug Administration (FDA) has cleared among a number of other applications the treatment of hamburger patties to eliminate the residual risk of a contamination by a virulent E. coli. The United Nations Food and Agricultural Organization (FAO) has passed a motion to commit member states to implement irradiation technology for their national phytosanitary programs; the General assembly of the International Atomic Energy Agency (IAEA) has urged to make wider use of the irradiation technology. Additionally, the USDA has made a number of bi-lateral agreements with developing countries to facilitate the imports of exotic fruits and to simplify the quarantine procedures.

The European Union has regulated processing of food by ionizing radiation in specific directives since 1999; the relevant documents and reports are accessible online.[7] The "implementing" directive contains a "positive list" permitting irradiation of only dried aromatic herbs, spices, and vegetable seasonings.[8] However, any Member State is permitted to maintain previously granted clearances or to add new clearance as granted in other Member States, in the case the EC's Scientific Committee on Food (SCF) has given a positive vote for the respective application. Presently, six Member States (Belgium, France, Italy, Netherlands, Poland, United Kingdom) have adopted such provisions.[9]

Because of the "Single Market" of the EC, any food — even if irradiated — must be allowed to be marketed in any other Member State even if a general ban of food irradiation prevails, under the condition that the food has been irradiated legally in the state of origin. Furthermore, imports into the EC are possible from third countries if the irradiation facility had been inspected and licensed by the EC and the treatment is legal within the EC or some Member state.[10]

The Scientific Committee on Food (SCF) of the EC has given a positive vote on eight categories of food to be irradiated.[11] However, in a compromise between the European Parliament and the European Commission, only dried aromatic herbs, spices, and vegetable seasonings can be found in the positive list. The European Commission was due to provide a final draft for the positive list by the end of 2000; however, this failed because of a veto from Germany and a few other Member States. In 1992,[12] and in 1998[13] the SCF voted "positive" on a number of irradiation applications that had been allowed in some member states before the EC Directives came into force, to enable those member states to maintain their national authorizations.

In 2003, when Codex Alimentarius was about to remove any upper dose limit for food irradiation, the SCF adopted a "revised opinion",[14] which in fact was a re-confirmation and endorsement of the 1986 opinion. The opinion denied cancellation of the upper dose limit, and required that before the actual list of individual items or food classes (as in the opinions expressed in 1986, 1992 and 1998) can be expanded, new individual studies into the toxicology of each of such food and for each of the proposed dose ranges are requested. The SCF has subsequently been replaced by the new European Food Safety Authority (EFSA), which has not yet ruled on the processing of food by ionizing radiation.

Other countries, including New Zealand, Australia, Thailand, India, and Mexico, have permitted the irradiation of fresh fruits for fruit fly quarantine purposes, amongst others. Such countries as Pakistan and Brazil have adopted the Codex Alimentarius Standard on Irradiated Food without any reservation or restriction: i.e., any food may be irradiated to any dose.

Radiation absorbed dose

"Dose" is the physical quantity governing the radiation processing of food, relating to the beneficial effects to be achieved.


Unit of measure for irradiation dose

The dose of radiation is measured in the SI unit known as Gray (Gy). One Gray (Gy) dose of radiation is equal to 1 joule of energy absorbed per kg of food material. In radiation processing of foods, the doses are generally measured in kGy (1,000 Gy).


The measurement of radiation dose is referred to as dosimetry, and involves exposing dosimeters jointly with the treated food item.[15][16] Dosimeters are small components attached to the irradiated product made of materials that, when exposed to ionizing radiation, change specific, measurable physical attributes to a degree that can be correlated to the dose received. Modern dosimeters are made of a range of materials, such as alanine pellets, perspex (PMMA) blocks, and radiochromic films, as well as special solutions and other materials. These dosimeters are used in combination with specialized read out devices. Standards that describe calibration and operation for radiation dosimetry, as well as procedures to relate the measured dose to the effects achieved and to report and document such results, are maintained by the American Society for Testing and Materials (ASTM international) and are also available as ISO/ASTM standards.[17]


On the basis of the dose of radiation the application is generally divided into three main categories as detailed under:

Low Dose Applications (up to 1 kGy)

  • Sprout inhibition in bulbs and tubers 0.03-0.15 kGy
  • Delay in fruit ripening 0.25-0.75 kGy
  • Insect disinfestation including quarantine treatment and elimination of food borne parasites 0.07-1.00 kGy

Medium Dose Applications (1 kGy to 10 kGy)

  • Reduction of spoilage microbes to prolong shelf-life of meat, poultry and seafoods under refrigeration 1.50–3.00 kGy
  • Reduction of pathogenic microbes in fresh and frozen meat, poultry and seafoods 3.00–7.00 kGy
  • Reducing the number of microorganisms in spices to improve hygienic quality 10.00 kGy

High Dose Applications (above 10 kGy)

  • Sterilisation of packaged meat, poultry and their products which are shelf stable without refrigeration. 25.00-70.00 kGy
  • Sterilisation of Hospital diets 25.00-70.00 kGy
  • Product improvement as increased juice yield or improved re-hydration

It is important to note that these doses are above those currently permitted for these food items by the FDA and other regulators around the world. The Codex Alimentarius Standard on Irradiated Food does not specify any upper dose limit.[18][19] NASA is authorized to sterilize frozen meat for astronauts at doses of 44 kGy as a notable exception.[20]

Irradiation treatments are also sometimes classified as radappertization, radicidation and radurization.[21]

Table of the history of food irradiation

  • 1895 Roentgen discovers X-rays ("bremsstrahlung", German for radiation produced by deceleration)
  • 1896 Antoine Henri Becquerel discovers natural radioactivity; Minck proposes the therapeutic use[22]
  • 1904 Samuel Prescott describes the bactericide effects Massachusetts Institute of Technology (MIT)[23]
  • 1906 Appleby & Banks: UK patent to use radioactive isotopes to irradiate particulate food in a flowing bed[24]
  • 1918 Gillett: U.S. Patent to use X-rays for the preservation of food[25]
  • 1921 Schwartz describes the elimination of Trichinella from food[26]
  • 1930 Wuest: French patent on food irradiation[27]
  • 1943 MIT becomes active in the field of food preservation for the U.S. Army[28]
  • 1951 U.S. Atomic Energy Commission begins to co-ordinate national research activities
  • 1958 World first commercial food irradiation (spices) at Stuttgart, Germany[29]
  • 1970 Establishment of the International Food Irradiation Project (IFIP), head quarters at the Federal Research Centre for Food Preservation, Karlsruhe, Germany
  • 1980 FAO/IAEA/WHO Joint Expert Committee on Food Irradiation recommends the clearance generally up to 10 kGy "overall average dose"
  • 1981/1983 End of IFIP after reaching its goals
  • 1983 Codex Alimentarius General Standard for Irradiated Foods: any food at a maximum "overall average dose" of 10 kGy
  • 1984 International Consultative Group on Food Irradiation (ICGFI) becomes the successor of IFIP
  • 1997 FAO/IAEA/WHO Joint Study Group on High-Dose Irradiation recommends to lift any upper dose limit
  • 2003 Codex Alimentarius General Standard for Irradiated Foods: no longer any upper dose limit
  • 2004 ICGFI ends


Electron irradiation

Electron irradiation uses electrons accelerated in an electric field to a velocity close to the speed of light. Electrons are particulate radiation and, hence, have cross section many times larger than photons, so that they do not penetrate the product beyond a few inches, depending on product density. Electron facilities rely on substantial concrete shields to protect workers and the environment from radiation exposure.

Gamma irradiation

Gamma radiation is radiation of photons in the gamma part of the electromagnetic spectrum. The radiation is obtained through the use of radioisotopes, generally cobalt-60 or, in theory, caesium-137. Cobalt-60 is intentionally bred from cobalt-59 using specifically designed nuclear reactors. Caesium-137 is recovered during the refinement of "spent nuclear fuel", formerly referred to as "nuclear waste". Because this technology — except for military applications — is not commercially available, insufficient quantities of it are available on the global isotope markets for use in large scale, commercial irradiators. Presently, caesium-137 is used only in small hospital units to treat blood before transfusion to prevent Graft-versus-host disease.

Food irradiation using Cobalt-60 is the preferred method by most processors, because the deeper penetration enables administering treatment to entire industrial pallets or totes, reducing the need for material handling.[30] A pallet or tote is typically exposed for several minutes to hours depending on dose. Radioactive material must be monitored and carefully stored to shield workers and the environment from its gamma rays. During operation this is achieved by substantial concrete shields. With most designs the radioisotope can be lowered into a water-filled source storage pool to allow maintenance personnel to enter the radiation shield. In this mode the water in the pool absorbs the radiation. Other uncommonly used designs feature dry storage by providing movable shields that reduce radiation levels in areas of the irradiation chamber.

One variant of gamma irradiators keeps the Cobalt-60 under water at all times and lowers the product to be irradiated under water in hermetic bells. No further shielding is required for such designs.

X-ray irradiation

Similar to gamma radiation, X-rays are photon radiation of a wide energy spectrum and an alternative to isotope based irradiation systems. X-rays are generated by colliding accelerated electrons with a dense material (target) such as tantalum or tungsten in a process known as bremsstrahlung-conversion. X-ray irradiators are scalable and have deep penetration comparable to Co-60, with the added effect of using an electronic source that stops radiating when switched off. They also permit dose uniformity. However, these systems generally have low energetic efficiency during the conversion of electron energy to photon radiation requiring much more electrical energy than other systems. Like most other types of facilities, X-ray systems rely on concrete shields to protect the environment and workers from radiation.

Nominal X-ray energy is usually limited to 5 MeV; however, USA has provisions for up to 7.5 MeV which increases the conversion efficiency. Another development is the availability of electron accelerators with extremely high power output, up to 1,000 kW beam. At a conversion efficiency of up to 12%, the X-ray power may reach (including filtering and other losses) 100 kW; This power would be equivalent to a gamma facility with Co-60 of about 6.5 MCi.

Irradiated foods in the market place

Current U.S. market

Some U.S. supermarkets carry irradiated food products today ranging from fresh tropical fruit from Hawaii or Florida,[31] dehydrated spices[32], spinach[33] and ground meat products.[34][35] Certain supermarkets like Whole Foods Market prefer not to carry irradiated products for reasons of consumer perception.

General economic aspects

Some foods, particularly fruits and vegetables, are not available for sale on the global market unless treated to prolong shelf life for transportation. This may include radiation processing. However, this application has not yet been exploited. In contrast, irradiation to eliminate insect pests to fulfill quarantine requirements is gaining commercial significance. This is true for fruits Hawaii exports to the U.S. mainland, and increasingly for imports from subtropical countries to the U.S. under bilateral agreements that allows those less-developed countries to earn income through food exports. As an example, Mexico has started to export irradiated guava to the U.S. in 2008, Mango in 2009 and has received approval for Citrus, Star Fruit and Manzano Chili. Furthermore, a number of Asian countries hold bilateral agreements to irradiate exotic fruits for quarantine purposes and export it to the USA.

The actual cost of food irradiation is influenced by dose requirements, the food's tolerance of radiation, handling conditions, i.e., packaging and stacking requirements, construction costs, financing arrangements, and other variables particular to the situation.[36] Irradiation is a capital-intensive technology requiring a substantial initial investment, ranging from $1 million to $5 million. In the case of large research or contract irradiation facilities, major capital costs include a radiation source (cobalt-60), hardware (irradiator, totes and conveyors, control systems, and other auxiliary equipment), land (1 to 1.5 acres), radiation shield, and warehouse. Operating costs include salaries (for fixed and variable labor), utilities, maintenance, taxes/insurance, cobalt-60 replenishment, general utilities, and miscellaneous operating costs[37][38]

Treatment costs vary as a function of dose and facility usage. Low dose applications such as disinfestation of fruit range between US$0.01/lbs and US$0.08/lbs while higher dose applications can cost as much as US$0.20 / lbs.[38]

Consumer perception

Irradiation has not been widely adopted due to an asserted negative public perception, the concerns expressed by some consumer groups and the reluctance of many food producers.[39]

Consumer organizations, environmentalist groups, and opponents to food irradiation refer to some studies suggesting that a large part of the public questions the safety of irradiated foods, and will not buy foods that have been irradiated.[40]

On the other hand, other studies indicate the number of consumers concerned about the safety of irradiated food has decreased in the last 10 years and continues to be less than the number of those concerned about pesticide residues, microbiological contamination, and other food related concerns. The number of people reporting no concerns about irradiated food is among the lowest for food issues, comparable to that of people with no concern about food additives and preservatives. Consumers, given a choice and access to the real irradiated product are ready to buy it in considerably large numbers.[41][42]

The globalized food supply

Opponents of food irradiation sometimes state that large-scale irradiation would increase processing, transportation, and handling times for fruits and vegetables thus contributing to a negative ecological balance compared to locally grown foods.[citation needed]

Labeling and terminology issues

Labeling laws differ from country to country. While Codex Alimentarius represents the global standard in particular under the WTO-agreement, member states are free to convert those standards into national regulations. With regard to labelling of irradiated food, detailed rules are published at CODEX-STAN — 1 (2005) labelling of prepacked food.[43]

The provisions are that any "first generation" product must be labeled "irradiated" as any product derived directly from an irradiated raw material; for ingredients the provision is that even the last molecule of an irradiated ingredient must be listed with the ingredients even in cases where the unirradiated ingredient will not appear on the label. The RADURA-logo is optional; several countries use a graphical version which differs from the Codex-version.

In the U.S., as in many other countries, irradiated food must be labeled as "Treated with irradiation" or "Treated by radiation" and require the usage of the Radura symbol at the point of sale. However, the meaning of the label is not consistent. The amount of irradiation used can vary and since there are no published standards, the amount of pathogens affected by irradiation can be variable as well. In addition, there are no regulations regarding the levels of pathogen reduction that must be achieved. Food that is processed as an ingredient by a restaurant or food processor is exempt from the labeling requirement in the US; other countries follow the Codex Alimentarius provision to label irradiated ingredients down to the last molecule (cf. EU).

FDA is currently proposing a rule that in some cases would allow certain irradiated foods to be marketed without any labeling at all. Under the new rules, only those irradiated foods in which the irradiation causes a material change in the food, or a material change in the consequences that may result from the use of the food, would bear the Radura symbol and the term "irradiated", or a derivative thereof, in conjunction with explicit language describing the change in the food or its conditions of use. In the same rule FDA is proposing to permit a firm to use the terms "electronically pasteurized" or "cold pasteurized" in lieu of "irradiated", provided it notifies the agency that the irradiation process being used meets the criteria specified for use of the term "pasteurized".[44]

Food irradiation is sometimes referred to as "cold pasteurization"[45] or "electronic pasteurization"[46] because ionizing the food does not heat the food to high temperatures during the process, as in heat-pasteurization (at a typical dose of 10 kGy, food that is physically equivalent to water would warm by about 2.5 °C). The treatment of solid food by ionizing radiation can provide an effect similar to heat pasteurization of liquids, such as milk. However, the use of the term, cold pasteurization, to describe irradiated foods is controversial, because pasteurization and irradiation are fundamentally different processes, although the intended end results can in some cases be similar.

Consumer perception of foods treated with irradiation is more negative than those which processed using other food processes. "People think the product is radioactive," said Harlan Clemmons, president of Sadex, a food irradiation company based in Sioux City, Iowa.[47]

Enforcement of labelling

There are analytical methods available to detect the usage of irradiation on food items in the marketplace.[48][49][50] This may be understood as a tool for government authorities to enforce existing labeling standards and to bolster consumer confidence. The European Union is particularly strict in enforcing irradiation labeling requiring its member countries to perform tests on a cross section of food items in the market-place and to report to the European Commission; the results are published annually in the OJ of the European Communities.[51]

United States Regulators of Food Irradiation

The Radura logo, as required by U.S. Food and Drug Administration regulations to show a food has been treated with ionizing radiation.

Food irradiation in the United States is primarily regulated by the FDA[52] since it is considered a food additive. Other federal agencies that regulate aspects of food irradiation include:

Each new food is approved separately with a guideline specifying a maximum dosage; in case of quarantine applications the minimum dose is regulated. Packaging materials containing the food processed by irradiation must also undergo approval.[54]

Note: The Radura logo as regulated by FDA is slightly different from the international version as proposed in Codex Alimentarius.[43]

Safety aspects

Safety, security and wholesomeness aspects

Hundreds of animal feeding studies of irradiated food, including multigenerational studies, have been performed since 1950.[55] Endpoints investigated have included subchronic and chronic changes in metabolism, histopathology, and function of most systems; reproductive effects; growth; teratogenicity; and mutagenicity. A large number of studies have been performed; meta-studies have supported the safety of irradiated food.[55][56][57][58][59]

Consumer advocacy groups such as Public Citizen or Food and Water Watch maintain that the safety of irradiated food is not proven, in particular long-term studies are still lacking, and strongly oppose the use of the technology.[60][61]

A report of fatal incidences with pet food in Australia [62] led to some rumours and speculations about the safety of irradiated food and a nationwide recall. In the Australian case 16 cats were reported to have been euthanized after severe paralysis subsequent to being fed a certain cat food[63] The company issuing a recall stated that the problem only occurred with Australian pet-food. The company speculated this was due to irradiating the pet-food. The Australian Quarantine Inspection Services (AQIS) (at that time) required the irradiation to a minimum dose of 50 kGy or heating of imported dry food.[64] After the incident, the pet food manufacturer created a compassion fund for pet owners.[65] The cause of the cat illness is not yet clearly understood and is still under investigation and verification. Vitamin A depletion wasn't confirmed in the affected cats.[66] Researchers from Wisconsin University announcing their conference presentation said in the published abstract: "Here, we show that cats fed an irradiated diet during gestation developed a severe neurologic disease resulting from extensive myelin vacuolation and subsequent demyelination." [67] There are several Youtube videos claiming to show cats suffering from irradiated food[68] and a video including excerpts from an interview with Dr. Georgina Childs, the veterinarian from SASH involved in the initial cat cases.[69]

There has been news that radiation processing of imported cat food has now been banned in Australia.[70] Previously it had been a mandatory requirement for imports including dry and semi-moist food to be irradiated at a minimum dose of 50 kGy or to be heated to a temperature of 100 °C (212 °F) for a minimum of 30 minutes. Actually, the AQIS — having jurisdiction on quarantine issues — has announced with date of 2009-06-06 that the alternative of radiation processing for cat food is no longer acceptable and that irradiated dog food needs to be labeled by "Must not be fed to cats".[71][72] AQIS in its announcement refers to recently published scientific studies and reminds importers of their responsibility to regularly check whether new scientific results could have any implication for their products. This is to say a "ban" of food irradiation does not exist; and the theory about the causes of ataxia with cats food irradiated products has not been proven. Meanwhile, Dr. G. Child has published a report of the clinical signs and outcomes of those cats.[73] The authors point to epidemiological and to toxicological studies which are still underway. It is not yet clear by which mechanism and what changes induced in the irradiated pet food the damages in the white matter of spinal cord and brain are caused.

Criticism and concerns about food irradiation

Concerns have been expressed by public interest groups and public health experts that irradiation, as a non-preventive measure, might disguise or otherwise divert attention away from poor working conditions, sanitation, and poor food-handling procedures that lead to contamination in the first place.[74]

A complaint list may contain the following concerns and objections[75] which not all can be covered and discussed in this article:

Food irradiation might
- be used to mask spoiled food,
- discourage strict adherence to Good Manufacturing Practices,
- preferentially kill "good" bacteria, encourage growth of "bad" bacteria,
- devitalize and denature irradiated food,
- impair the flavour,
- not destroy bacterial toxins already present,
- cause chemical changes which are harmful to the consumer,
- and, on top of all, is unnecessary in today's food system.

"Food irradiation is a pseudo-fix," said Bill Freese, a science policy analyst with the Center for Food Safety in Washington, DC. "It's a way to try to come in and clean up problems that are created in the middle of the food production chain. I think it's clearly a disincentive to clean up the problems at the source."[76]

Processors of irradiated food are subject to all existing regulations, inspections, and potential penalties regarding plant safety and sanitation; including fines, recalls, and criminal prosecutions. But critics of the practice claim that a lack of regulatory oversight (such as regular food processing plant inspections) necessitates irradiation.[77] "[Irradiation] is a total cop-out," said Patty Lovera, assistant director of Food and Water Watch. "They don't have the resources, the authority or the political will to really protect consumers from unsafe food."[78]

While food irradiation can in some cases maintain the quality (ie. general appearance and "inner" quality) of certain perishable food for a longer period of time, it cannot undo spoilage which has occurred prior to irradiation. Irradiation cannot be successfully used to mask quality issues other than pathogens. However, as heat pasteurization (example milk), processing by ionizing radiation can contribute to eliminate pathogen risks from solid food (example meat or lettuce). Milk heat-pasteurization is not considered to be a method "to cover up poor food quality"; consequently, food irradiation should not be accused to serve such criminal purposes[75]. Under a HACCP-concept (Hazard Analysis and Critical Control Point) radiation processing can serve and contribute as an ultimate critical control point before the food reaches the consumer.

Opponents to food irradiation and consumer activists frequently state that the final proof is missing that irradiated food is "safe" (i.e. not unwholesome). Moreover, the lack of long-term studies should be a further reason not to permit food irradiation. Such questions, by the principle, cannot be answered by science as any scientist should have learned during his studies. Proving the absence of a negative is virtually impossible. For such reasons the basic question needs to be rephrased: What are the chances — the probabilities — that consuming irradiated food will in some way produce unhealthful effects? The scientific consensus is "very slim".[79] A few quick answers to possible questions:

Do irradiated foods cause cancer or genetic damage? It has never happened.
Does irradiation change the chemical composition of whatever is irradiated? Of course it does. That's why it works. (Some details in other sections of this article)

Long-term studies have already been carried on huge numbers of laboratory animals, many species and multiple generations. No negative effects have been observed which could be correlated in a causal way to the irradiation treatment of the food. However, the absence of a noxious effect cannot be proven by the principle, even not in long-term studies. A further complaint is that animal studies cannot be transferred to humans.

There are many more concerns of such kind and the answers have to be found by validating the scientific evidence.

Of course and quite naturally, during the now more than 60 years of research into food irradiation and possibly harmful effects a number of publications have reported such deleterious effects among others as

- polyploidy in malnourished Indian children
- increase of aflatoxin production by irradiated microorganisms
- vitamin deficiencies at extremely high doses to the complete diet
- non-vitamin effects at higher doses (free radicals?)
- change in chronaxie with rats

However, those experiments could be either not verified in later experiments, could not be clearly attributed to the radiation effect, could be attributed to an inappropriate design of the experiment etc.

In more recent experiments a number of new issues have been raised as

- possible tumor promoting effect of 2ACBs in extremely high concentrations
- ataxie caused in Australian cats by high-dose irradiated imported feed
- multiple sclerosis caused intentionally in cats by high-dose irradiated feed
- specific effects caused only in pregnant cats by high-dose irradiated feed

In particular, for those very specific situations of those experiments it would be indispensable to defermine whether those animal models have any relevance for human nutrition. Typically, food as intended for human consumption is never irradiated at such extremely high dose levels; on the other hand, feed sterilization by ionizing irradiation is widely accepted standard in rearing of laboratory animals (eg. SPF-free) and in producing gnotobiotic animals for agricultural production.

Worker safety and impact on the environment

The safety of irradiation facilities is regulated by the United Nations International Atomic Energy Agency and monitored by the different national Nuclear Regulatory Commissions. The incidents that have occurred in the past are documented by the agency and thoroughly analyzed to determine root cause and improvement potential. Such improvements are then mandated to retrofit existing facilities and future design.

Care must be taken not to expose the operators and the environment to radiation or radioactive contamination. Interlocks and safeguards are mandated to minimize this risk. Nevertheless there have been radiation related deaths and injury amongst workers of such facilities, many of them caused by the operators themselves overriding the interlocks.[80] It should be noted that "ordinary" occupational safety regulations also apply to radiation processing facilities; the radiation aspect are typically excluded and supervised by special authorities.

An incident in Decatur, Georgia where water soluble caesium-137 leaked into the source storage pool requiring NRC intervention[81] has led to near elimination of this radioisotope; it has been replaced by the more costly, non-water soluble cobalt-60.

National and international regulations on the levels and types of energy used to irradiate food generally set standards that prevent the possibility of inducing radioactivity in treated foods, and, hence, excluding the risk to workers and the environment.


Other methods to reduce several pathogens in food include heat-pasteurization, ultra-high temperature processing, UV radiation, ozone or fumigation with ethylene oxide.

For quarantine purposes, insect pests can also be eliminated by fumigation with methyl bromide or aluminum phosphine, vapour heat, forced hot air, hot water dipping, or cold treatment.

Other methods to extend shelf life of food items include modified atmosphere packaging, carbon monoxide, dehydration, vacuum packaging, freezing and flash freezing as well as chemical additives.

Opponents to food irradiation and consumer activists (cf. Public Citizen[60]) maintain that the best alternative to food irradiation to reduce pathogens is in good agricultural practices. For example, farmers and processing plants should improve sanitation practices, water used for irrigation and processing should be regularly tested for E. coli, and production plants should be routinely inspected. Concentrated animal feeding operations near farmland where produce is grown should be regulated.

Proponents of food irradiation have said that practices of organic farming can only reduce the extent of the microorganism load. They assert that residual flora including pathogen germs will always persist; and that processing by ionizing radiation could be the ultimate measure (as a CCP under a HACCP-concept) to practically eliminate such risks.[82][83][84]

See also

Further reading

  • World Health Organization publications:
    • Food irradiation — A technique for preserving and improving the safety of Food, WHO, Geneva, 1991 (revised)
    • Wholesomeness of irradiated food, WHO, Geneva, Technical Report Series No. 659, 1981
    • Safety and nutritional adequacy of irradiated food, WHO, Geneva, 1994
    • High-dose irradiation: Wholesomeness of food irradiated with doses above 10 kGy, WHO, Geneva, 1999, Technical Report Series No. 890
    • WHO Statement on 2-Dodecylcyclobutanone and Related Compounds
  • Facts about Food Irradiation, A series of Fact Sheets from the International Consultative Group on Food Irradiation (ICGFI), 1999, IAEA, Vienna, Austria [1]
  • Diehl, J.F., Safety of irradiated food, Marcel Dekker, N.Y., 1995 (2. ed.)
  • Satin, M., Food irradiation, Technomic, Lancaster, 1996 (2. ed.)
  • Urbain, W.M., Food irradiation, Academic Press, Orlando, 1986
  • Molins, R. (ed.), Food irradiation — Principles and applications, Wiley Interscience, N.Y., 2001
  • Sommers, C.H. and Fan, X. (eds.), Food Irradiation Research and Technology, Blackwell Publishing, Ames, IA, 2006
  • Hauter, W. and Worth, M., Zapped! Irradiation and the Death of Food, Food & Water Watch Press, Washington, DC, 2008.

"The food that would last forever : understanding the dangers of food irradiation" by Gary Gibbs, Garden City Park, N.Y. : Avery Pub. Group, c1993


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  4. ^ C.M. Deeley, M. Gao, R. Hunter, D.A.E. Ehlermann, The development of food irradiation in the Asia Pacific, the Americas and Europe; tutorial presented to the International Meeting on Radiation Processing, Kuala Lumpur, 2006. <ef>,cntnt01,detail,0&cntnt01articleid=488&cntnt01detailtemplate=resourceCenter-publication-detail-template&cntnt01returnid=231&hl=en_US last visited 2010-02-18
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  6. ^ Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, IAEA, International Database on Insect Disinfestation and Sterilization — IDIDAS — last visited 2007-11-16
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"The food that would last forever : understanding the dangers of food irradiation" by Gary Gibbs, Garden City Park, N.Y. : Avery Pub. Group, c1993

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