Food irradiation is the process of exposing food to
ionizing radiationIonizing radiation consists of subatomic particles or electromagnetic waves that are energetic enough to detach electrons from atoms or molecules, ionizing them. The occurrence of ionization depends on the energy of the impinging individual particles or waves, and not on their number...
to destroy
microorganismA microorganism or microbe is an organism that is microscopic...
s,
bacteriaThe bacteria are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
,
virusA virus is an infectious agent too small to be seen directly with a light microscope. They are not made of cells and can only replicate inside the cells of another organism . Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
es, or
insectInsects are arthropods, having a hard exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae. They are the most diverse group of animals on the planet and include more than a million species that are already described. Insects represent more than half of all...
s that might be present in the food. Further applications include sprout inhibition, delay of ripening, increase of juice yield, and improvement of re-hydration.
IrradiationIrradiation is the process by which an item is exposed to radiation. The exposure can be intentional, sometimes to serve a specific purpose, or it can be accidental...
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
DNADeoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information...
, 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.
The speciality of processing food by ionizing radiation is that the energy density per atomic transition is very high; it can cleave molecules and induce
ionizationIonization is the physical process of converting an atom or molecule into an ion by adding or removing charged particles such as electrons or other ions. This is often confused with dissociation ....
(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.
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.,
herbA herb is a plant that is valued for flavor, scent, or other qualities. Herbs are used in cooking, as medicines, and for spiritual purposes....
s and
spiceA spice is a dried seed, fruit, root, bark, leaf, or vegetative substance used in nutritionally insignificant quantities as a food additive for the purpose of flavour, colour, or as a preservative that kills harmful bacteria or prevents their growth....
s) are irradiated at sufficient doses (five
kilograysThe gray is the SI unit of absorbed radiation dose due to ionizing radiation .-Definition:One gray is the absorption of one joule of energy, in the form of ionizing radiation, by one kilogram of matter....
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.
Furthermore, insect pests can be sterilized (be made incapable of proliferation) using irradiation at relatively low doses. In consequence, the
United States Department of AgricultureThe United States Department of Agriculture is the United States federal executive department responsible for developing and executing U.S. federal government policy on farming, agriculture, and food...
(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 AgencyThe International Atomic Energy Agency is an international organization that seeks to promote the peaceful use of nuclear energy and to inhibit its use for military purposes. It was established as an autonomous organization on 29 July 1957...
(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 UnionThe European Union is an economic and political union of 27 Member States, located primarily in Europe. Committed to regional integration, the EU was established by the Treaty of Maastricht on 1 November 1993 upon the foundations of the pre-existing European Economic Community...
has regulated processing of food by ionizing radiation in specific directives since 1999; the relevant documents and reports are accessible online.
The 'implementing' directive contains a 'positive list' permitting irradiation of only dried aromatic herbs, spices, and vegetable seasonings.
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.
Because of the '
Single MarketA common market is a type of trade bloc which is composed of a customs union with common policies on product regulation, and freedom of movement of the factors of production and of enterprise. The goal is that the movement of capital, labour, goods, and services between the members is as easy as...
' 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.
The Scientific Committee on Food (SCF) of the EC has given a positive vote on eight categories of food to be irradiated. However, in a compromise between the
European ParliamentThe European Parliament is the directly elected parliamentary institution of the European Union . Together with the Council of the European Union , it forms the bicameral legislative branch of the Union's institutions and has been described as one of the most powerful legislatures in the world...
and the
European CommissionThe European Commission acts as an executive of the European Union. The body is responsible for proposing legislation, implementing decisions, upholding the Union's treaties and the general day-to-day running of the Union.The Commission operates in the method of cabinet government, with 27...
, 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, and in 1998 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 AlimentariusThe Codex Alimentarius is a collection of internationally recognized standards, codes of practice, guidelines and other recommendations relating to foods, food production and food safety. Its name derives from the Codex Alimentarius Austriacus...
was about to remove any upper dose limit for food irradiation, the SCF adopted a 'revised opinion', 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 AuthorityThe European Food Safety Authority is an agency of the European Union that provides independent scientific advice and communication on existing and emerging risks associated with the food chain....
(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 flyFruit fly may refer to several organisms:* Tephritidae, the family of large fruit flies.* Drosophilidae, the family of small fruit flies and vinegar flies, including:...
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
GrayThe gray is the SI unit of absorbed radiation dose due to ionizing radiation .-Definition:One gray is the absorption of one joule of energy, in the form of ionizing radiation, by one kilogram of matter....
(Gy). One
GrayThe gray is the SI unit of absorbed radiation dose due to ionizing radiation .-Definition:One gray is the absorption of one joule of energy, in the form of ionizing radiation, by one kilogram of matter....
(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).
Dosimetry
The measurement of radiation dose is referred to as
dosimetryRadiation dosimetry is the calculation of the absorbed dose in matter and tissue resulting from the exposure to indirectly and directly ionizing radiation...
, and involves exposing
dosimeterDosimeters measure an individual's or an object'sexposure to something in the environment — particularly to a hazard inflicting cumulative impact over long periods of time, or over a lifetime...
s jointly with the treated food item. Dosimeters are small components attached to the irradiated product made of materials that, when exposed to
ionizing radiationIonizing radiation consists of subatomic particles or electromagnetic waves that are energetic enough to detach electrons from atoms or molecules, ionizing them. The occurrence of ionization depends on the energy of the impinging individual particles or waves, and not on their number...
, change specific, measureable 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.
Applications
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 AlimentariusThe Codex Alimentarius is a collection of internationally recognized standards, codes of practice, guidelines and other recommendations relating to foods, food production and food safety. Its name derives from the Codex Alimentarius Austriacus...
Standard on Irradiated Food does not specify any upper dose limit.
NASAThe National Aeronautics and Space Administration is an agency of the United States government, responsible for the nation's public space program. NASA was established by the National Aeronautics and Space Act on July 29, 1958, replacing its predecessor, the National Advisory Committee for...
is authorized to sterilize frozen meat for astronauts at doses of 44 kGy as a notable exception.
Irradiation treatments are also sometimes classified as
radappertizationRadappertization is a form of food irradiation which applies a dose of ionizing radiation sufficient to reduce the number and activity of viable microorganisms to such an extent that very few, if any, are detectable in the treated food by any recognized method...
,
radicidationRadicidation is a specific case of food irradiation where the dose of ionizing radiation applied to the food is sufficient to reduce the number of viable specific non-spore-forming pathogenic bacteria to such a level that none are detectable when the treated food is examined by any recognized...
and
radurizationRadurization is the application to food irradiation to foods using a dose of ionizing radiation sufficient to enhance its keeping quality by causing a substantial decrease in numbers of viable specific spoilage microorganisms. The required dose is in the range of 0.4 - 10 kGy....
.
Table of the history of food irradiation
- 1895 Roentgen
Röntgen or Roentgen may refer to:* Wilhelm Conrad Röntgen, German physicist* Abraham Röntgen and David Röntgen, German cabinetmakers* Julius Röntgen, German-Dutch composer...
discovers X-rays ('bremsstrahlung', German for radiation produced by deceleration)
- 1896 Antoine Henri Becquerel discovers natural radioactivity; Minck proposes the therapeutic use
- 1904 Samuel Prescott describes the bactericide effects Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological research...
(MIT)
- 1906 Appleby & Banks: UK patent to use radioactive isotopes to irradiate particulate food in a flowing bed
- 1918 Gillett: US-Patent to use X-rays for the preservation of food
- 1921 Schwartz describes the elimination of Trichinella from food
- 1930 Wuest: French patent on food irradiation
- 1943 MIT becomes active in the field of food presevation for the US-Army
- 1951 US AEC begins to co-ordinate national research activities
- 1958 World first commercial food irradiation (spices) at Stuttgart, Germany
- 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
The Codex Alimentarius is a collection of internationally recognized standards, codes of practice, guidelines and other recommendations relating to foods, food production and food safety. Its name derives from the Codex Alimentarius Austriacus...
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
The Codex Alimentarius is a collection of internationally recognized standards, codes of practice, guidelines and other recommendations relating to foods, food production and food safety. Its name derives from the Codex Alimentarius Austriacus...
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
photonIn physics, a photon is an elementary particle, the quantum of the electromagnetic field and the basic "unit" of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force...
s in the gamma part of the
electromagnetic spectrumThe electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....
. The radiation is obtained through the use of radioisotopes, generally
Cobalt-60Cobalt-60 is a radioactive isotope of cobalt. Due to its short half life of 5.27 years 60Co is not found in nature. It is produced artificially by neutron activation of 59Co. 60Co decays by negative beta decay to the stable isotope nickel-60...
or, in theory, Cesium-137. Cobalt-60 is intentionally bred from Cobalt-59 using specifically designed nuclear reactors.
Cesium-137 is recovered during the refinement of "spent nuclear fuel" formerly refered 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, Cesium-137 is used only in small hospital units to treat blood before transfusion to prevent
Graft-versus-host diseaseGraft-versus-host disease is a common complication of allogeneic bone marrow transplantation in which functional immune cells in the transplanted marrow recognize the recipient as "foreign" and mount an immunologic attack...
.
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. 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-rayX-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays...
s 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
tantalumTantalum is a chemical element with the symbol Ta and atomic number 73. A rare, hard, blue-gray, lustrous transition metal, tantalum is highly corrosion resistant and occurs naturally in the mineral tantalite, always together with the chemically similar niobium...
or
tungstenTungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A steel-gray metal, tungsten is found in several ores, including wolframite and scheelite...
in a process known as
bremsstrahlungBremsstrahlung , is electromagnetic radiation produced by the acceleration of a charged particle, such as an electron, when deflected by another charged particle, such as an atomic nucleus. The term is also used to refer to the process of producing the radiation...
-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.
Current U.S. market
Some U.S. supermarkets carry irradiated food products today ranging from fresh tropical fruit from Hawaii or Florida, dehydrated spices and ground meat products. Certain supermarkets like
Whole Foods MarketWhole Foods Market is an Austin, Texas-based foods grocer. , the company operates over 275 locations in the United States, Canada, and the United Kingdom....
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 Chile. Furthermore, a number of Asian countries hold bilateral agreements to irradiate exotiic 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. 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
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.
Consumer perception
Opponents to food irradiation, consumer organizations and environmentalist groups 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.
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.
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.
Labeling and terminology issues
Labeling laws differ from country to country. While
Codex AlimentariusThe Codex Alimentarius is a collection of internationally recognized standards, codes of practice, guidelines and other recommendations relating to foods, food production and food safety. Its name derives from the Codex Alimentarius Austriacus...
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.
The provisions are that any 'first generation' product must be labelled '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 US as in many other countries irradiated food must be labeled as "Treated with irradiation" or "Treated by radiation" and require the usage of the
RaduraThe Radura is the international symbol indicating a food product has been irradiated. The Radura is usually green and resembles a plant in circle. The top half of the circle is dashed...
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".
Food irradiation is sometimes referred to as 'cold pasteurization' or 'electronic pasteurization' 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.
Enforcement of labelling
There are analytical methods available to detect the usage of irradiation on food items in the marketplace.
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.
United States Regulators of Food Irradiation
Food irradiation in the United States is primarily regulated by the FDA since it is considered a food additive. Other federal agencies that regulate aspects of food irradiation include:
- United States Department of Agriculture
The United States Department of Agriculture is the United States federal executive department responsible for developing and executing U.S. federal government policy on farming, agriculture, and food...
(USDA) - meat and poultry products, fresh fruit
- Nuclear Regulatory Commission
Nuclear Regulatory Commission is a United States government agency that was established by the Energy Reorganization Act in 1974, and was first opened January 19, 1975. The NRC took over the role of oversight of nuclear energy matters and nuclear safety from the AEC, or Atomic Energy Commission...
(NRC) - safety of the processing facility
- United States Department of Transportation
The United States Department of Transportation is a federal Cabinet department of the United States government concerned with transportation. It was established by an act of Congress on October 15, 1966 and began operation on April 1, 1967...
(DOT) - safe transport of the radioactive sources
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.
note: The Radura logo as regulated by FDA is slightly different from the international version as proposed in Codex Alimentarius.
Safety, security and wholesomeness aspects
Hundreds of animal feeding studies of irradiated food, including multigenerational studies, have been performed since 1950. 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, some having demonstrated adverse effects of irradiation, and some concluding the process yields safer foods.
Consumer advocacy groups such as
Public Citizen-Introduction:Public Citizen is a non-partisan, politically left-of-center, non-profit public interest 'advocacy organization' based in Washington, D.C., with a branch in Austin, Texas...
or
Food and Water WatchFood & Water Watch is a Washington, D.C. based non-governmental organization and consumer rights group which focuses on corporate and government accountability relating to food, water, and fishing. Food and Water Watch employs a four pronged effort focusing on public and policymaker education,...
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.
A report of fatal incidences with pet food in Australia 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 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.. After the incident, the pet food manufacturer created a compassion fund for pet owners. 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. 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." There are several Youtube videos claiming to show cats suffering from irradiated feed and a video including excerpts from an interview with Dr. Georgina Childs, the veterinarian from SASH involved in the initial cat cases.
There has been news that radiation processing of imported cat feed has now been banned in Australia. Previously it had been a mandatory requirement for imports including dry and semi-moist feed to be irradiated at a minimum dose of 50 kGy or to be heated to a temperature of 100 °C 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 feed is no longer acceptable and that irradiated dog feed needs to be labeled by "Must not be fed to cats". 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 feed irradiation does not exist; and the theory about the causes of ataxia with cats feed irradiated products has not been proven.
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
contaminationContamination is the presence of a minor constituent in another chemical or mixture, often at the trace level. In chemistry, the term usually describes a single chemical, but in specialized fields the term can also mean chemical mixtures, even up to the level of cellular materials.All chemicals...
in the first place.
A complaint list may contain the following concerns and objections 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,
- - devitalise 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."
Processors of irradiated food are subject to all existing regulations, inspections, and potential penalties regarding plant safety and sanitization; 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.
"[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."
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. 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". 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 feed. But again, 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.
Worker safety and impact on the environment
The safety of irradiation facilities is regulated by the
United Nations International Atomic Energy AgencyThe International Atomic Energy Agency is an international organization that seeks to promote the peaceful use of nuclear energy and to inhibit its use for military purposes. It was established as an autonomous organization on 29 July 1957...
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. 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, GeorgiaDecatur is a city in, and county seat of, DeKalb County, Georgia, United States. With a population of 18,147 in the 2000 census, the city is sometimes assumed to be larger since multiple zip codes in unincorporated DeKalb County bear the Decatur name...
where water soluble
caesium-137Caesium-137 is a radioactive isotope of caesium which is formed mainly as a fission product by nuclear fission. It has a half-life of 30.17 years, and decays by beta decay to a metastable nuclear isomer of barium-137 . Barium-137m has a half-life of 2.55 minutes and is responsible for all of the...
leaked into the source storage pool requiring
NRCNuclear Regulatory Commission is a United States government agency that was established by the Energy Reorganization Act in 1974, and was first opened January 19, 1975. The NRC took over the role of oversight of nuclear energy matters and nuclear safety from the AEC, or Atomic Energy Commission...
intervention has led to near elimination of this radioisotope; it has been replaced by the more costly, non-water soluble
cobalt-60Cobalt-60 is a radioactive isotope of cobalt. Due to its short half life of 5.27 years 60Co is not found in nature. It is produced artificially by neutron activation of 59Co. 60Co decays by negative beta decay to the stable isotope nickel-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.
Alternatives
Other methods to reduce several pathogens in food include heat-
pasteurizationPasteurization is a process which slows microbial growth in food. The process was named after its creator, French chemist and microbiologist Louis Pasteur. The first pasteurization test was completed by Louis Pasteur and Claude Bernard on April 20, 1864...
, ultra-high temperature processing, UV radiation,
ozoneOzone or trioxygen is a simple triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic O
2. Ground-level ozone is an air pollutant with harmful effects on the respiratory systems of animals...
or fumigation with
ethylene oxideEthylene oxide, also called oxirane, is the organic compound with the formula C2H4O. This colorless flammable gas with a faintly sweet odor is the simplest epoxide, a three-membered ring consisting of two carbon and one oxygen atom. It is commonly handled and shipped as a...
.
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 monoxideCarbon monoxide is a colorless, odorless and tasteless gas, yet very toxic to humans. It consists of one carbon atom and one oxygen atom, connected by a covalent double bond and a dative covalent bond...
,
dehydrationDehydration is defined as excessive loss of body water. It is literally the removal of water from an object. In physiological terms, it entails a relative deficiency of water molecules in relation to other dissolved solutes...
, vacuum packaging,
freezingIn physical science, freezing or solidification is the process in which a liquid turns into a solid when cold enough. The freezing point is the temperature at which this happens. Melting, the process of turning a solid to a liquid, is almost the exact opposite of freezing...
and
flash freezingFlash freezing refers to the application of supercooling in various kinds of industries whereby objects are quickly frozen by subjecting them to cryogenic temperatures....
as well as chemical additives.
Opponents to food irradiation and consumer activists (cf. Public Citizen) 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.
See also
- Deinococcus radiodurans
Deinococcus radiodurans is an extremophilic bacterium, one of the most radioresistant organisms known. It can survive cold, dehydration, vacuum, and acid, and is therefore known as a polyextremophile and has been listed as the world's toughest bacterium in The Guinness Book Of World Records.-Name...
- Food labeling regulations
- Food and cooking hygiene
- Irradiated mail
Irradiated mail is mail that has been deliberately exposed to radiation, typically in an effort to disinfect it. The most notable instance of mail irradiation occurred in response to the 2001 anthrax attacks; the level of radiation chosen to kill anthrax spores was so high that it often changed the...
Further reading
- World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health...
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 http://www.iaea.org/programmes/nafa/d5/public/foodirradiation.pdf
- 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.
External links
- Codex Alimentarius
The Codex Alimentarius is a collection of internationally recognized standards, codes of practice, guidelines and other recommendations relating to foods, food production and food safety. Its name derives from the Codex Alimentarius Austriacus...
- Food Irradiation Processing Alliance FIPA represents the irradiation service industry, manufacturers of food irradiators and suppliers of cobalt-60 sources.
- Food & Water Watch -- food irradiation page
- U.S. Food Irradiation FAQ, Food and Water Watch
Food & Water Watch is a Washington, D.C. based non-governmental organization and consumer rights group which focuses on corporate and government accountability relating to food, water, and fishing. Food and Water Watch employs a four pronged effort focusing on public and policymaker education,...
- Remarks by Mark Worth, Public Citizen, to the FDA, Jan. 12, 2005
- Irradiation of Food and Food Packaging, Center for Food Safety and Applied Nutrition
The Center for Food Safety and Applied Nutrition is the branch of the United States Food and Drug Administration that regulates food, dietary supplements, and cosmetics.-Area of regulation:...
- Irradiation Fact Sheet, Center for Food Safety and Applied Nutrition
The Center for Food Safety and Applied Nutrition is the branch of the United States Food and Drug Administration that regulates food, dietary supplements, and cosmetics.-Area of regulation:...
- Facts about Food Irradiation, a series of 14 fact sheets, International Consultative Group on Food Irradiation, International Atomic Energy Agency
The International Atomic Energy Agency is an international organization that seeks to promote the peaceful use of nuclear energy and to inhibit its use for military purposes. It was established as an autonomous organization on 29 July 1957...
, Vienna, 1991
- Bibliography on Food Irradiation, Federal Research Centre for Nutrition and Food, Karlsruhe, Germany
Karlsruhe is a city in the south west of Germany, in the Bundesland Baden-Württemberg, located near the French-German border....
- Should we irradiate fruit and vegetables? Dateline NBC
Dateline NBC, or Dateline, is a U.S. weekly television newsmagazine broadcast by NBC. It is similar in scope to ABC's 20/20 or CBS's 60 Minutes.-History:...
investigation
- Irradiation FAQ provided by BENEBION of Mexico
- anon. What's wrong with food irradiation, revised Feb. 2001, Organic Consumers Association, USA
- Comment by Dr. Henry Delincée on an affidavit misrepresenting the conclusions of his studies on unique radiolytical byproducts
- The Basics on the Foodfight Over Irradiation | health.usnews.com