Caballero B. (ed.) Encyclopaedia of Food Science, Food Technology and Nutrition. Ten-Volume Set

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Shellfish

0043 Shellfish are prone to heavy contamination by patho-

genic and spoilage bacteria. Frozen shellfish can be

decontaminated using 2–5 kGy with little quality loss.

Fresh shellfish (peeled/unpeeled) can be treated with

1–2 kGy, doubling shelf-life, but quality decreases at

higher doses. Refrigeration below 4



C is essential.

Viral contamination of shellfish cannot be reduced

by these dose levels. (See Shellfish: Contamination

and Spoilage of Molluscs and Crustaceans.)

0044 Black spot occurs on shrimps when they are stored.

Radiation inhibits its formation provided the shrimp

is very fresh when irradiated.

Other Possible Uses of Irradiation

0045 A number of other uses of irradiation have been

implemented or proposed (Table 4).

See also: Cereals: Handling of Grain for Storage;

Escherichia coli: Occurrence and Epidemiology of

Species other than Escherichia coli Fish: Spoilage of

Seafood; Legumes: Legumes in the Diet; Meat:

Preservation; Oxidation of Food Components; Poultry:

Chicken; Ducks and Geese; Ripening of Fruit; Shellfish:

Contamination and Spoilage of Molluscs and

Crustaceans; Spoilage: Molds in Spoilage; Yeasts in

Spoilage; Vegetables of Temperate Climates: Stem and

Other Vegetables

Further Reading

Anonymous (1989) Ionizing Energy in Food Processing and

Pest Control. II. Applications. A Task Force Report no.

115. Ames, Iowa: Council for Agricultural Science and

Technology.

Anonymous (1992) Irradiation of Spices, Herbs and Other

Vegetable Seasonings; a Compilation of Data for its

Regulation and Control. IAEA-TECDOC-639. Vienna,

Austria: International Atomic Energy Agency.

Anonymous (1993) Irradiation of Poultry Meat and its

Products; a Compilation of Data for its Regulation and

Control. IAEA-TECDOC-688. Vienna, Austria: Inter-

national Atomic Energy Agency.

Anonymous (1997) Irradiation of Bulbs and Tuber Crops; a

Compilation of Data for its Regulation and Control.

IAEA-TECDOC-937. Vienna, Austria: International

Atomic Energy Agency.

Elias PS and Cohen AJ (eds) (1983) Recent Advances in

Food Irradiation. Amsterdam, The Netherlands: Else-

vier.

Josephson EJ and Peterson MS (eds) (1982) Preservation of

Foods by Ionizing Radiation, vol. III. Boca Raton, FL:

CRC Press.

Shay BJ, Egan AF and Wills PA (1988) The use of irradi-

ation for extending the storage life of fish and processed

meats. Food Technology in Australia 40: 310–313.

Thomas P (1986) Radiation preservation of foods of plant

origin. Part V. Temperate fruits: pome fruits, stone fruits

and berries. CRC Critical Reviews in Food Science and

Nutrition 24: 357–400.

Urbain WM (1986) Food irradiation. Food Science and

Technology: A Series of Monographs. Orlando, FL:

Academic Press.

World Health Organization (1994) Safety and Nutritional

Adequacy of Irradiated Food. Geneva: World Health

Organization.

Processing Technology

P B Roberts, Institute of Geological and Nuclear

Sciences Ltd, Lower Hutt, New Zealand

Introduction

0001This chapter describes the facilities required to irradi-

ate food, how to measure the absorbed dose, and

the likely processing costs. Suitable packaging and

methods to detect irradiated foods are also outlined.

General Description of Irradiation Plants

0002All irradiation facilities have the following compon-

ents (Figure 1):

tbl0004 Table 4 Other suggested benefits of the irradiation of foodstuffs

Foodstuff Proposed benefit Likely dose range (kGy)

Wheat flour Increased loaf size from low-sugar formulations 0.5–1

Nuts Insect control 1

Beans Oligosaccharide reduction 2–3

Egg powder/dried whole egg Decontamination 2–6

Frog legs (frozen) Decontamination 2–7

Grapes Increased juice yield 4–5

Fruit juices/purees Stabilization 5–10

Cured meats Nitrite reduction 7.5–30

Animal feed Decontamination/sterilization 7–30

Complete meals Sterilization (for immunosuppressed patients) 30–50

3390 IRRADIATION OF FOODS/Processing Technology

.0003 a source of radiation in an irradiation chamber

0004 a protective shield

0005 a conveyor system

0006 a general area containing a control room or control

console and warehouse space

Source

0007 The commonly used sources of radiation are cobalt-

60, a radioactive element emitting g-rays, or an

accelerator producing a beam of electrons.

0008 Cobalt-60 is produced by neutron bombardment of

stable cobalt in a nuclear reactor. Small nickel-plated

slugs of the radioactive metal are loaded into a sealed

alloy cylinder typically 10 450 mm and doubly

encapsulated in a corrosion-resistant steel pencil. An

array of such pencils is built into a rack typically

1–2m

. Cobalt-60 decays continuously. The time

taken to lose 50% of its initial activity, i.e., its half-

life, is 5.26 years. Usually 10% of the cobalt-60 is

replenished annually.

0009 There are several types of electron accelerator but

all produce a fast-moving stream of electrons in a

narrow beam that is rapidly scanned across a 0.2–

1.2 m wide ‘horn’ positioned above the food to be

irradiated. Radiation is produced only when the

machine is switched on. The source strength can be

varied within limits by altering the operating current

or voltage.

Shielding

0010The irradiation chamber is enclosed by a 1.5–2m

thick concrete shield. This incorporates a maze system

through which the food is conveyed to the source.

The shield and maze reduce direct and reflected radi-

ation levels in the general areas of the facility to safe

levels and prevent exposure of the plant staff to radi-

ation. In cobalt-60 plants penetrating g-rays are emit-

ted continuously in all directions. The radioactive

source requires a nonoperating position in which all

the radiation can be absorbed, making the chamber

safe for staff to enter. This position is at the bottom of

a 7 m deep pool of water set into the chamber floor. A

hoist moves the source between operating and non-

operating positions.

0011Electrons (10 MeV) are absorbed within a few

centimeters in condensed matter. However, penetrat-

ing X-rays are produced when electrons strike objects

within the chamber. Therefore, shielding is just as

necessary in accelerator facilities as in g-plants,

although its design may be simpler. The accelerator

is simply switched off when staff enter the chamber.

Conveyor

0012Some g-plants operate in a batch mode. Food is

carried into the chamber with the source nonopera-

tional, then irradiated and removed. However, a

Irradiated

product

dispatch

Food

reception

Control

console

fig0001 Figure 1 A diagrammatic representation of a cobalt-60 food irradiation plant. The arrows depict the movement of the food through

the irradiation chamber and around the central source. Reproduced from Irradiation of Foods: Processing Technology. Encyclopaedia

of Food Science, Food Technology and Nutrition, Macrae R, Robinson RK and Sadler MJ (eds), 1993, Academic Press.

IRRADIATION OF FOODS/Processing Technology 3391

conveyor system carrying food continuously past the

source is more usual. Conveyor design must insure

that the food is irradiated with reasonable uniformity.

The speed of the conveyor and, hence, the time spent

near the source is a major determinant of the dose

received.

0013 A railed system is used to transport large containers

(up to 1 1.21.8 m) past cobalt-60 sources in a

single- or multiple-pass arrangement. The latter pro-

vides more efficient absorption of radiation and more

uniform dose distribution.

0014 An electron beam is emitted in one basic direction.

This and its limited penetration permit only thin

layers of food to be treated under the beam. A simple

moving belt acts as the conveyor. Electron beams

have been used mainly to treat grains, seeds, and

homogenous meat products up to 70 mm thick.

General Area

0015 Controls and servicing equipment are housed outside

the shielded area. Areas for receiving incoming food

and storing irradiated product are kept separate and

contain temperature-controlled rooms if necessary.

Beam Penetration

0016 Figure 2 illustrates the ability of g-rays and electrons

to penetrate food packages. Two-sided irradiation

doubles the thickness treatable and reduces the dose

variations within the package.

0017 A completely uniform dose throughout a package

is not feasible. The ratio of maximum to minimum

dose is called the dose uniformity (DU) and should be

as close to unity as possible. This is achieved more

easily by treating thinner packages, a strategy that

wastes radiation energy and reduces the volume

treated in a given time. DU values close to unity in

bulky packages are achieved more easily with g-rays

than with electrons (Figure 2).

0018 Acceptable DU values differ for different foods and

processes. The minimum dose must guarantee the

intended effect and the maximum must not be detri-

mental to the food. Initial plant design must balance

the acceptable DU, the throughput required for

economic operation, and the range of doses required.

Dosimetry

0019 The energy absorbed by the food (i.e., the dose) is the

most important parameter in the treatment process.

Standards and Reference Dosimeters

0020 The dose can be measured absolutely by calorimetry

or ionization chamber methods. Calorimetry

measures the heat released into water; ionization

chambers record the number of ion pairs produced

in air. Specialized laboratories have used both

methods to provide national standards and reference

dosimeters.

0021However, any effect that varies detectably and re-

producibly with dose can be used as a reference dos-

imeter provided its response can be calibrated against

a national standard. The Fricke dosimeter is a par-

ticularly well-characterized and common reference

dosimeter. It consists of an aqueous solution of fer-

rous sulfate and sulfuric acid. Free radicals produced

during irradiation oxidize ferrous ions to ferric ions, a

change detected as an increase in optical absorption.

Doses in the range 10–400 Gy can be measured by

Fricke dosimetry. A small modification to the solution

extends the range to 2 kGy.

140

120

100

0 2 4 6 8 10 12 14 16

Depth (cm)

140

120

100

02468

Dose as a percentage

of surface dose

Dose as a percentage

of surface dose

(a)

(b)

fig0002Figure 2 The relationship between dose and depth for unit

density packages exposed to (a) cobalt-60 g-rays or (b) 10 MeV

electrons either from one side (1) or two sides (2). Adapted from

Cleland MR, Pageau GM (1985) Electron versus gamma rays –

alternative sources for irradiation processes. Food Irradiation

Processing. Proceedings of a Symposium, Washington DC, March,

pp. 397–406. Vienna, Austria: International Atomic Energy

Agency, with permission.

3392 IRRADIATION OF FOODS/Processing Technology

In-plant Dosimetry

0022 The reference dosimeters are difficult to use routinely

in commercial operations. More practical dosimeters

comprise plastic materials such as polymethylmetha-

crylate. Small pellets of the plastic, either clear or

colored by dye, can be easily handled and change

color over a wide dose range. The color induced

gradually fades. Such dosimeters must be calibrated

against a reference dosimeter that has itself been

calibrated against a national standard.

0023 When any food is presented initially for irradia-

tion, potential dose variations throughout the

food must be assessed in trial runs. Plastic dosimeters

are placed strategically throughout the food container

to map the dose distribution. The positions of

maximum and minimum dose (D

max

, D

min

) are

determined and checked against the prescribed

treatment protocol.

0024 During routine operations some packages that con-

tain dosimeters at the points receiving D

max

and D

min

are conveyed past the source. Most operators provide

a label that is impregnated with a radiation-sensitive

dye on the outside of every package. The label changes

color upon radiation. It is a simple yes/no indication

that the package has been treated rather than a true

dosimeter.

Overall Average Absorbed Dose

0025 Technically, the important dose parameters are

max

and D

min

since these will determine the quality

and effectiveness of the treatment. However, the

Codex General Standard for Irradiated Food refers

to an overall average value, D

. This is rigorously

defined as:

pðx; y; xÞdðx; y; zÞdV

where M is the total mass of product, p is the density at

a point defined by the coordinates (x, y, z), d is the

absorbed dose at (x, y, z)anddV is the infinitesimal

volume element. D

can only be determined in an

extensive dose-mapping exercise. However, the simple

equation:

max

þ D

min

is often sufficient.

0026 The Code General Standard for Irradiated Foods

recommends a maximum dose in terms of a D

value

of 10 kGy. At least 97.5% of the food should receive

less than 15 kGy. The dose uniformity should also be

optimized. This is usually interpreted as DU values

less than 2, but higher values are acceptable for some

applications using low doses.

Plant Capacity and Costs

0027If all the radiation emitted by the source is absorbed

in the food then a source of 1 kW can treat 360 kg of

food per hour to a dose of 10 kGy. However, radi-

ation is wasted when some of the beam misses or

passes completely through the food. Some radiation

is absorbed within the source or in the conveyor

system. The percentage of radiation actually used,

the efficiency factor (E), is usually 20–50%. Simple

cobalt plants have relatively low-efficiency factors.

Large multiple-pass cobalt plants and electron beam

facilities can be designed with an E value approaching

50%.

0028A useful equation for the production rate of a

plant is:

T ¼

3600S

where T is the throughput (kg h

1

), S is the source

power (kW), D is the minimum dose (kGy), and E is

the efficiency factor.

0029The source power is given by the cobalt-60 activity

(1 kW ¼67 kCi or 2.5 PBq) or the accelerator voltage

and current (1 kW ¼1 MeV 1 mA).

0030Plant costs depend on the processing capability

(volume and dose) required and, hence, on the source

power and warehouse space. Costs can be in the

range US$1–6 million. For a typical 1 MCi (37 PBq)

cobalt-60 plant the source, the conveyor system, and

the building each account for about one-third of the

total cost.

0031Processing costs depend upon whether a high or

low dose is required and on the source power. If

sufficient volumes of food are available to dedicate

the plant to a paticular purpose (e.g., poultry decon-

tamination), then the plant can be designed to maxi-

mize efficiency. Most plants treat a variety of foods

for different purposes and require greater flexibility

at added cost.

0032In general, processing costs increase in proportion

to the dose required and are approximately US$10–

100 per tonne over a range of low- to high-dose

applications.

Food Handling

0033Irradiation resembles pasteurization and fumigation

in its ability to reduce the bioburden of pathogenic

organisms in food. However, such methods must not

be used to substitute for good hygiene practices at any

stage in the pre- or posttreatment handling of food.

Ideally, irradiation should be integrated within a

Hazard Analysis Critical Control Point (HACCP)

system. Codex has prepared guidelines for the use of

HACCP systems.

IRRADIATION OF FOODS/Processing Technology 3393

0034 Overall standards of food handling are discussed

in the Codex General Principles of Food Hygiene.

Operating standards within an irradiation plant are

covered in a Codex Recommended International

Code of Practice for the Operation of Irradiation

Facilities Used for the Treatment of Food. (See Fumi-

gants; Pasteurization: Principles.)

0035 Irradiation can penetrate foods prepackaged in

plastic or simple insect-proof wrapping. Food such

as poultry, fruit, or vegetables can be decontaminated

or disinfested in their final package, ready for trans-

port, storage, or display. This eliminates the risk of

recontamination until the package is opened by the

purchaser.

0036 For some irradiation treatments (e.g., inhibition of

sprouting), foods such as potatoes can be treated

loose in suitable totes or containers. If foods for

which temperature control is an essential part of

good storage technique are irradiated, then the plant

must have suitable areas set aside to control the tem-

perature. Special care may be needed with seafoods

and some meats in which resistant Clostridium botu-

linum spores can survive irradiation. Subsequent

growth of the bacterium would produce a fatal

toxin, but this is prevented by storage below 4



(See Clostridium: Occurrence of Clostridium botuli-

num.)

0037Irradiation while food is frozen or vacuum-packed

inhibits the free radical reactions leading to oxidation

rancidity and off-flavors. Treatment while frozen and

under vacuum was originally proposed for foods

intended for very-high-dose treatments (50–60 kGy)

to make them shelf-stable indefinitely at room tem-

perature. The product is an attractive alternative to

canned food. Since Codex presently recommends that

dose is limited to 10 kGy, the application of food

tbl0001 Table 1 Approvals of packaging materials for use in conjunction with irradiation of food

Packaging material Maximum dose (kGy) Country(approvaldate)

Cardboard 10; 35 UK; Poland (1991)

Polyethylene coextruded polyvinylacetate 30 US; Canada (1988)

Polyethylene-co-vinylacetate 30 US (1989)

Fiberboard 10 India (1997)

Fiberboard, wax-coated (boxes) 10 US; Canada (1989)

Glassine paper 10 US (1975)

Glass 10 India (1997)

Hessian sacks 10 UK (1991)

Kraft paper 0.5 US (1975)

Nitrocellulose-coated cellophane 10 US: India (1975)

Nylon 11 10 US; India (1975)

Nylon 6 60; 10 US; India (1975)

Paper 10; 35 UK; Poland (1991)

Paper coated or laminated with wax or polyethylene 10; 35 India; Poland (1990)

Paper laminated with aluminum foil 35 Poland (1990)

Polyamide film or polyamide coextruded with polyethylene 35 Poland (1990)

Polyester-metalized-polyethylene laminate 35 Poland (1990)

Polyester-polyethylene laminate 35 Poland (1990)

Polyethylene film (various densities) 60; 35; 10 US; Poland; India (1975)

Polyethylene-paper-aluminum laminate 35 Poland (1990)

Polyethylene-terephthalate 60 US (1975)

Polyolefin (low-destiny as middle or sealant layer) Canada (1989)

Polyolefin (high-density as external layer) Canada (1989)

Polyolefin film 10 US (1975)

Polypropylene sacks 10; 35 UK; Poland (1990)

Polypropylene – metalized 35 Poland (1990)

Polystyrene film 10 US; India (1975)

Polystyrene foam trays (Styron 685D) 10 Canada; India (1989)

Rubber hydrochloride film 10 US; India (1975)

Steel, tin plates or enamel-lined 10 India (1997)

Vegetable parchment 60; 10 US; India (1975)

Vinylchloride-co-vinylacetate film 60; 10 US; India (1975)

Vinylidenechloride-coated cellophane 10 US (1975)

Vinylchloride-co-vinylidenechloride film 10 US; India (1975)

Wood 35; 10 Poland; India (1990)

Viscosa 35 Poland (1990)

Data available through the International Consultative Group on Food Irradiation, International Atomic Energy Agency, Vienna.

The earliest approval date is given.

3394 IRRADIATION OF FOODS/Processing Technology

irradiation to produce sterile shelf-stable foods in

light plastic packaging has received little attention.

However the conclusion of a World Health Organiza-

tion Study Group in 1999 that foods irradiated to any

practical dose above 10 kGy are safe and nutritious

may lead to more interest in this application.

Packaging

0038 Packaging must meet standards for the retention of

postirradiation stability, strength, and permeability.

The risk of low-molecular-weight chemicals in the

irradiated packaging (e.g., stabilizers) diffusing into

the food must also be negligible.

0039 Table 1 lists the packaging materials approved by

the US Food and Drug Administration and by regula-

tory authorities in Canada, Poland, India, and the UK

for concurrent use when food is irradiated.

Labeling and Detection of Irradiated

Foods

0040 Irradiation is one of a group of food processes that

leave no obvious signs to a purchaser, food inspector,

or retailer that a food has been processed. Labeling of

irradiated foods is generally considered desirable. In

its General Standard for Labelling of Pre-packaged

Food, Codex recommends use of the phrase ‘irradi-

ated [name of food]’ or ‘treated by ionizing radi-

ation.’ Most countries legislate for this wording or a

near equivalent to be used with complete foods that

have been irradiated. The words are placed on the

food package or are prominently displayed near foods

sold in bulk containers.

0041 There is considerable debate about the labeling of

irradiated minor ingredients or components of a food.

The practicality, cost, and need for such labeling

are questioned. National regulations vary in their

requirements.

0042Methods to detect irradiated foods would boost

consumer confidence in legislative controls, particu-

larly that labeling information was accurate. Un-

ambiguous detection of an irradiated food proved

to be a difficult problem. No single method for all

foods seems feasible. However, international collab-

orative trials have established a number of detection

methods. Table 2 summarizes the methods that are

established or under further investigation. Germany

and the UK have official protocols in place for the use

of some methods to enforce labeling requirements.

Postprocessing detection is not a suitable way to

control actual processing conditions.

See also: Clostridium: Occurrence of Clostridium

botulinum; Fumigants; Hazard Analysis Critical Control

Point; Legislation: Codex; Pasteurization: Principles;

Plant Design: Process Control and Automation

Further Reading

Anonymous (1991) Code of Good Irradiation Practice for

Insect Disinfestation of Cereal Grains. International

Consultative Group on Food Irradiation Document

no. 3 and related codes in this series. Vienna, Austria:

International Atomic Energy Agency.

Beers EW (1990) Innovations in irradiator design. Radi-

ation Physics and Chemistry 35: 539–546.

Cleland MR and Pageau GM (1985) Electrons versus

gamma rays – alternative sources for irradiation pro-

cesses. Food Irradiation Processing. Proceedings of a

Symposium, Washington DC, March, pp. 397–406.

Vienna, Austria: International Atomic Energy Agency.

Food and Agriculture Organization (1984) Codex Recom-

mended International Code of Practice for the Oper-

ation of Radiation Facilities Used for the Irradiation

Treatment of Foods (CAC/RCP 19–1979 Rev 1) Codex

Alimentarius, vol XV. Rome, Italy: Food and Agriculture

Organization of the United Nations.

Food and Agriculture Organization (1991) Codex General

Standard for the Labelling of Prepackaged Foods

tbl0002 Table 2 Major methods of detecting irradiated foods

Method Basis Suitable foods Status

Electron spin resonance Free radicals, paramagnetic centers in rigid

matrices (e.g., bone, shell, seeds)

Meat (bone in), shellfish,

some fruit

Established

Thermoluminescence

Centers of energy excess or deficit in dry

material

Herbs, spices, shellfish Established

Gas chromatography–

mass spectrometry

Radiation products from volatile fatty acids Meat, lipid-containing

foods

Advanced, standardization

required

Impedance Change in electrical properties Potato Advanced, wider testing required

Microbiology Change in microbial population Most uncooked foods Well developed, indicative test

only, not definitive

DNA alterations Damage to DNA bases and strand breaks Most uncooked foods Experimental

The signal arises mainly from adherent minerals (soil, dust). Mineral separation leads to better discrimination and wider applications. A related method

using light rather than heat to release stored energy is very promising but suitable equipment is lacking in most laboratories.

IRRADIATION OF FOODS/Processing Technology 3395

(Codex STAN 1–1985, Rev. 1–1991) Codex Alimentar-

ius. Rome, Italy: Food and Agriculture Organization of

the United Nations.

McKeown J and Sherman NK (1985) Linac based irradia-

tors. Radiation Physics and Chemistry 25: 103–109.

McLaughlin WL, Boyd AW, Chadwick KH, McDonald JC

and Miller A (1989) Dosimetry for Radiation Process-

ing. London, UK: Taylor and Francis.

McMurray CH, Stewart EM, Gray R and Pearce J (1996)

Detection Methods for Irradiated Foods: Current Status.

London, UK: Royal Society of Chemistry.

Morrison RM (1990) Economics of food irradiation: com-

parison between electron accelerators and cobalt-60.

Radiation Physics and Chemistry 35: 673–680.

Swallow AJ (ed.) (1989) Food irradiation. Radiation

Physics and Chemistry 34: 875–1030.

Thayer DW (1988) Chemical changes in food packaging

resulting from ionising irradiation. In: Hotchkiss JH

(ed.) Food and Packaging Interactions. ACS Symposium

Series, no. 365. Washington, DC: American Chemical

Society.

Thompson CC and Cleland MR (1989) High power dyna-

mitron accelerators for X-ray processing. Nuclear In-

struments and Methods B40/41: 1137–1141.

Legal and Consumer Aspects

P B Roberts, Institute of Geological and Nuclear

Sciences Ltd, Lower Hutt, New Zealand

Background

0001 Governments have a responsibility to ensure the safe

use of facilities that involve radiation sources, includ-

ing those used to process food. An increase in the

present limited commercial use of food irradiation

will depend on the regulatory environment at

national and global level, and on the attitude of the

food industry and consumers to the product. This

article discusses these issues.

Legislative Principles

0002 Governments control the processing of food by vari-

ous legislative methods. Some governments approve a

particular treatment, whereas others may license a

facility. In some countries, a single agent or minister

is responsible. In other countries, multiple agencies

must approve different aspects of the process and the

sale of products.

0003 Although regulatory mechanisms differ, there are a

few basic principles that authorities should adopt to

ensure the safe irradiation processing of food. These

are summarized within a number of international

documents, in particular:

0004Codex General Standard for Irradiated Foods;

0005Codex Recommended International Code of Prac-

tice for the Operation of Irradiation Facilities for

the Treatment of Food;

0006Codex General Standard for the Labelling of Pre-

packaged Food;

0007Codex General Principles of Food Hygiene, and

related Codes of Practice for specific commodities;

0008Codex Hazard Analysis and Critical Control Point

System and Guidelines for its Application.

Radiation Safety

0009Staff within the plant, as well as the public, must be

protected against the radiation emitted by the source.

Most countries already have effective controls in

place to deal with nonfood uses of irradiation facil-

ities. Authorities refer to international guidelines of

the International Atomic Energy Agency for the

following:

0010permissible exposures of the workforce and public;

0011safe handling, transportation and disposal of radio-

active material;

0012safe operation of high-energy accelerators and

sources containing large amounts of radioactivity

activity;

0013emergency procedures in the event of accidents.

Radioactivity cannot be induced in food unless it is

irradiated with radiation above a threshold energy.

Therefore, the types and maximum energy of the

radiation used to process food are restricted to the

following:

0014g-rays emitted by the radionuclides cobalt-60 and

cesium-137;

0015X-rays generated by machine sources operated

at or below 5 MeV;

0016electrons generated by machine sources operated

at or below 10 MeV. (See Radioactivity in Food.)

Food Hygiene

0017The irradiation facility must meet the design, con-

struction, and general operating criteria imposed on

all well-regulated food handling plants. Authorities

must also take into account the packaging and

temperature requirements of the food while in the

treatment plant.

0018Irradiation must not be used to relax current stand-

ards of hygiene during any stage in the production,

storage, transportation, processing, or sale of food-

stuffs. The food presented for irradiation must meet

all normal standards of microbiological and general

3396 IRRADIATION OF FOODS/Legal and Consumer Aspects

quality, and must have been produced under condi-

tions of good manufacturing practice for which

Codex standards and other guidelines are available.

In this way, irradiation will confer further benefit or

enhanced safety on high-quality food.

Prior Approval and Quality Control

0019 There is no routine method of checking whether or

not food has been irradiated, or of estimating the dose

received once the food has left the facility. Therefore,

the management and operation of the plant must be

adequate at all times to guarantee proper control of

the process. This is achieved by requiring prior ap-

proval of the irradiation of foodstuffs and of the

facility. The approval process considers the following

factors:

0020 staffing (numbers, training, skills, supervision);

0021 dosimetry methods and standards;

0022 ability to assess initial, especially microbiological,

quality;

0023 separation of incoming and treated food;

0024 measures to prevent accidental reirradiation;

0025 hygienic storage and handling techniques and

conditions;

0026 record-keeping and documentation;

0027 regular inspection by authorities.

The overall goal of the approval process should be to

meet the principles of the Codex Recommended

International Code of Practice for the Operation of

Radiation Facilities used for the Treatment of Foods.

(See Quality Assurance and Quality Control.)

International Trade

0028 Foods are subject to documentary requirements when

traded internationally. Importing countries often

require assurance that the regulatory environment in

which the processors operate is at least as stringent as

their own. Minimum information on documentation

should be as follows:

0029 an identification number for the batch of food;

0030 the treatment given (dose, purpose, place, and date

of processing);

0031 the national regulations under which treatment

was approved;

0032 any special handling requirements such as tempera-

ture control.

Laboratory methods are becoming available to prove

that foods have been irradiated, although it remains a

major problem to estimate absorbed doses once the

product has left the irradiation plant. Therefore, it

remains necessary for countries to ensure that irradi-

ated foods are properly tracked as they move in trade,

and that documentation accompanies each shipment.

This will require effective cooperation between

countries.

Labeling

0033A label is the only way by which consumers can be

informed about whether a food has been irradiated.

There is no obligation to inform consumers about

some competing technologies (e.g., chemical sprout

inhibition, fumigation). However, commercial use of

irradiation has coincided with a growing recognition

of the consumer’s right to be informed and make a

considered choice about which foods to purchase.

0034A secondary reason for use of labeling is the

prevention of fraud (i.e., false claims in regard to

whether foods have or have not been irradiated).

0035The Codex General Standard for Pre-packaged

Food recommends the use of terms such as ‘irradiated

(name of food)’ or ‘treated with ionizing radiation’

for English-speaking countries. In France, the term

‘ionization’ is favored. If a food is sold in a prepack-

aged form, the label will be on the package. Foods

sold loose will have the information provided close to

the food container.

0036Figure 1 illustrates the international symbol or logo

for irradiated foods. It would be a simple visual guide

to consumers and the international food trade that a

food or ingredient had been irradiated. However, its

use as the sole identifier of irradiated foods has not

been supported by consumer organisations. A logo

may be considered as a voluntary addition to the

mandatory text.

fig0001Figure 1 The international logo for irradiated foods.

IRRADIATION OF FOODS/Legal and Consumer Aspects 3397

Role of International Organizations

0037 International organizations such as the Food and

Agriculture Organization (FAO), the World Health

Organization (WHO), and the International Atomic

Energy Agency (IAEA) support the irradiation pro-

cessing of food as a contribution to safe and secure

food supplies. In 1984, these organizations agreed to

sponsor the International Consultative Group on

Food Irradiation (ICGFI) to act as an international

group of experts designated by governments to evalu-

ate and advise on global activities in food irradiation.

0038 A priority for ICGFI is to encourage trade in irradi-

ated foods by working towards regulatory require-

ments that are as consistent as possible in different

countries. The ICGFI has issued a number of docu-

ments that advise on the control of food irradiation

processing. These include:

0039 Guidelines for Preparing Regulations for the

Control of Food Irradiation Facilities;

0040 International Inventory of Authorized Food Irradi-

ation Facilities;

0041 Guidelines for the Authorization of Food Irradi-

ation Generally or by Food Classes;

0042 Codes of Good Irradiation Practice for individual

commodities (amalgamated into a single Code in

2000) and associated monographs of technical data.

The Codex Alimentarius Commission has also issued

important documents related to regulating food

irradiation, as discussed elsewhere in this series of

articles.

International Status of Food Irradiation

(1999)

0043 Forty-one countries have informed the Joint Division

of the FAO/IAEA that they have listed at least one

type of food as cleared for irradiation for one or more

purposes. Although the Codex General Standard de-

clares that any food can be irradiated up to an overall

average dose of 10 kGy, most countries regulate

irradiation using the principles of food additives and

still require each food or application to be approved

on a case-by-case basis.

0044 Some countries have specific regulations on food

irradiation, and the list of approved items is part of

the regulation. In other countries, the list of approved

items has been drawn up by a statutory agency or

special committee. There is no specific food irradi-

ation regulation, but an authorization can be given

within general food regulations.

0045 A few governments (e.g., Luxembourg, Sweden)

have a policy that precludes the irradiation of food

or the sale of irradiated food products, though this is

not always reflected directly in legislation. Others

have a regulation that provides for an overall prohib-

ition on irradiation of foods but with the possibility to

seek an exemption for specified foods and purposes

(e.g., Australia, New Zealand).

0046The listing of countries and approved foods

appears extensive. However, the existence of an

approval does not necessarily mean that there is

automatic authorization to proceed with commercial

processing. Usually, it is still necessary to make a

specific application to process food, to provide

justification, and to show that good manufacturing

practice will be carried out.

0047Over 40 different foods or food classes have been

approved for irradiation for a variety of purposes,

and about 50 irradiation facilities worldwide treat

food. However, most of these facilities treat only

very small volumes of food.

0048Two aspects of national regulations, in particular,

can vary greatly between countries. One is labeling,

especially the labeling of food ingredients. The Codex

General Standard on Labeling of Pre-packaged Foods

is being interpreted in different ways. Some countries

require no labeling of irradiated foodstuffs once the

food becomes an ingredient in another food; others

require labeling regardless of how small a proportion

that an irradiated ingredient constitutes of the com-

plete food; other countries make no reference to

labeling.

0049Another cause of nonuniformity concerns the

allowable doses of radiation applied to the food.

The Codex Standard allows irradiation of food up

to a maximum overall average dose of 10 kGy.

This maximum is based on very conservative safety

and nutritional considerations. In practice, it is also

necessary for processors to limit the dose range

applied to foods for technological reasons. These

reasons include ensuring that the intended benefit is

achieved, for which a minimum dose is necessary,

and retaining the quality of the food, for which a

maximum below 10 kGy may be necessary. These

technological limits, which are basically advisory

and the business of the radiation processor, are often

included in national regulations in different ways in

different countries.

0050In 1999, the WHO published the findings of a

Study Group on the wholesomeness of food irradi-

ated above 10 kGy. It concluded that foods treated

above 10 kGy were safe and nutritionally adequate

when produced under conditions of good manufac-

turing practice. Thus, on the grounds of safety, there

is no need to legislate a maximum safe dose for irradi-

ation of food. The maximum can be determined by

the need to retain the quality and sensory properties

of food acceptable to consumers.

3398 IRRADIATION OF FOODS/Legal and Consumer Aspects

0051 During 2000, the Codex Alimentarius Commission

will review the implications of the Study Group find-

ing for its General Standard on Irradiated Foods,

particularly the recommended maximum dose limit.

This may then influence the way in which national

regulations deal with dose limits.

0052 Two exceptions to the 10-kGy maximum are al-

ready recognized in some countries. Higher doses

may be permitted to sterilize minor food ingredients

such as herbs and spices or foods for special groups

such as hospital patients, astronauts, or the armed

forces.

Consumer Issues

0053 Food irradiation has remained a specialized process

used for small volumes of food. In developed Western

countries, this is mainly because of reluctance on the

part of retailers and the food industry to adopt the

process. This industry position has arisen from initial

doubts or a lack of understanding about the process

by consumers. Without widespread acceptance of the

process in US and European markets, developing

countries have little incentive to invest in irradiation

facilities.

Formation of Consumer Opinion

0054 Resistance to irradiated foods was initially based on a

misapprehension that the food became radioactive.

Among the public and the media, there persists an

inability to distinguish between radiation and radio-

activity and between eating an irradiated product and

being irradiated. Accidents such as Three Mile Island

and Chernobyl reinforced these misapprehensions.

However, if such confusion were the sole reason for

consumer resistance to irradiated foods, it would be

relatively easy to counter.

0055 There are a number of general issues related dir-

ectly or indirectly to food irradiation:

0056 Interest in natural, unprocessed foods has grown.

Associated with this has been a perception of the

harmful health consequences of additives and pro-

cessing. Doubts about the safety of irradiated foods

continue to be expressed in spite of expert opinion.

0057 Consumers’ rights to choose and to be informed

about their food are widely accepted. The possible

additional costs and requirements for accurate and

informative labeling reinforce the reluctance of

food retailers to stock irradiated foods.

0058 There remains a general opposition to any new

technology that uses radioactive material or

radiation.

This mix of issues has ensured that food irradiation

has maintained a profile as a controversial process in

the media and among consumer activist groups that is

hardly warranted by its present importance as a food

technology.

Consumer Attitudes

0059Consumer attitudes vary greatly by country and are

dependent on development status, the extent to which

irradiated foods are available and media exposure.

Surveys of consumer attitudes (e.g., Table 1) have

shown that most members of the public are unaware

or have little knowledge of food irradiation. When

surveyed for an initial reaction, most consumers are

either unwilling to purchase irradiated foods or ex-

press strong reservations. Individual opposition may

decrease when the process is explained more fully.

General opposition tends to increase when conflicting

pro- and antiirradiation views are publicized.

0060Consumer opinion has been studied most closely in

the USA, where there has also been a substantial

public debate on the issue to help inform the con-

sumer. As information has been made available, con-

sumer concern has decreased. In the late 1980s, over

40% of consumers surveyed expressed serious con-

cern about irradiation. By 1996, this had fallen to less

than 30%.

0061Several studies in the USA indicate that up to 20%

of consumers oppose the irradiation of foods and are

unlikely to change that view. A similar percentage is

willing to try irradiated foods on the basis of minimal

information. The remainder are open to persuasion in

either direction on the basis of the information placed

before them.

0062Some surveys have found that concern about irradi-

ation ranks far lower than other concerns related to

food safety (Table 2). Irradiation was classed as a ser-

ious concern by 29% of US consumers surveyed, com-

pared with 77 and 66% seriously concerned about

bacteria and pesticides, respectively. Nitrites, additives,

and other preservatives elicited slightly less concern

than irradiation. In the longer term, the fact that

tbl0001Table 1 Concerns and awareness about food irradiation in the

1986

(%)

1989

(%)

Very concerned 25 36

Fairly concerned 44 42

Neither concerned nor unconcerned 8 7

Not very concerned 13 8

Not at all concerned 8 6

Don’t know/not stated 1 1

Previously aware of the term ‘food irradiation’ 48 55

The survey base was 2000 adults.

Data from Consumers’ Association (1990) Food Irradiation: The Consumer’s

View. London: Consumer’s Association.

IRRADIATION OF FOODS/Legal and Consumer Aspects 3399