Food irradiation
(Last updated August 2011)
What is food irradiation?
Food irradiation—a food safety, food preservation or quarantine measure used in more than 50 countries—is a process in which food is exposed to a source of ionising energy. Irradiation provides processors with a further safe alternative to treat foods. For example, processors may use irradiation to treat herbs and spices in place of chemical treatments. Or they may use irradiation to destroy the unwanted pests that can accompany food when it is traded regionally or imported from other countries.
Decades of research worldwide has shown that irradiation of food is a safe and effective way to kill bacteria in foods, extend its shelf life and reduce insect infestation. Food irradiation has been examined thoroughly by joint committees of the World Health Organization (WHO), the United Nations Food and Agriculture Organization (FAO), by the European Community Scientific Committee for Food, the United States Food and Drug Administration, by a House of Lords committee and by experts here in Australia and New Zealand.
What happens when food is irradiated?
Irradiated food does not become radioactive. When the treatment stops, energy does not remain in the food. The gamma rays of radioactive Cobalt 60 do not have enough energy to make food radioactive. Also, the food does not come into contact with the energy source, so it cannot become contaminated by radioactive material.
Irradiation causes minimal changes to the chemical composition of the food, though many of these changes that do occur are similar to those formed when food is cooked or preserved in more traditional ways.
Even where irradiation of a particular food is permitted for the specified purpose, it must not be used to clean up food which is unsafe or unsuitable.
Doesn’t irradiation of food lead to unique toxic chemicals being produced?
There are a number of compounds that may be generated during irradiation of food. However, most of these compounds are not unique to irradiated food and are naturally present at low levels in food or are formed through other processing treatments (e.g. thermal processing). 2-alkylcyclobutanones (2-ACBs) were thought to be a novel class of compounds formed as a result of irradiation of fat-containing food, with the types and concentrations of 2-ACBs in irradiated food dependent on the type of fat and the irradiation dose.
Perceived health concerns over 2-ACBs stem from their apparently unique formation in irradiated foods and the induction of some effects in some non-standard toxicology tests. FSANZ’s most recent assessment indicates that 2-ACBs previously considered to be uniquely formed during food irradiation are actually also naturally present in some non-irradiated foods (e.g. cashew nuts). Reviews on 2-ACBs that are based on the current scientific evidence, conclude that 2-ACBs in irradiated foods do not pose a health risk to consumers.
When can food be irradiated?
Food can only be irradiated if there is a specific purpose e.g. to make the food safer for consumers or for quarantine purposes to reduce insect infestation and specific permission must be obtained from Food Standards Australia New Zealand (FSANZ). FSANZ makes an assessment of each food type and each FSANZ recommendation is also considered by the Legislative and Governance Forum on Food Regulation.
This stringent approval process includes consideration of the technological need for the irradiation treatment and consideration of the effects on the food composition and the nutritional impact.
Where approvals related to the use of irradiation for a quarantine purpose, FSANZ liaises with both Biosecurity Australia and the New Zealand Ministry of Agriculture and Forestry to ensure that irradiation will achieve the outcome of reduction in pests that may be a significant quarantine threat to Australia or New Zealand.
What foods are irradiated?
To date, in Australia and New Zealand, only herbs and spices, herbal infusions and some tropical fruits have been approved to be irradiated. For each of the permitted applications FSANZ has established there are no safety concerns, that there are no significant changes in the nutritional content of the food and there is a technological need.
How do consumers know if food has been irradiated?
A package of food that has been irradiated, or food that contains irradiated ingredients or components, must be labelled with a statement that the food, ingredients or components have been treated with ionising radiation.
There are also labelling requirements for food not otherwise required to bear a label, for example:
- whole fruits sold loose by supermarkets
- restaurant meals containing ingredients that have been irradiated
- a take away pizza made with an irradiated herb as an ingredient
- a portion of curry made with irradiated spices, sold at a fund raising event.
In the absence of a label, the mandatory labelling statement must be displayed in close proximity to the food. The international radura symbol (below) may be used in addition to the mandatory labelling and, if used, should be in close proximity to the name of the food.
Current use of irradiation in Australian and New Zealand foods and in exported foods.
There are currently no irradiated mangoes, papaya or litchi’s available for sale in Australia.
The New Zealand Ministry of Agriculture and Forestry approved access to the New Zealand market for Australian mangoes in 2004, papaya in 2006 and litchi in 2008. Irradiation is the approved treatment for insects of concern to New Zealand and the minimum dose required by New Zealand for the insect pests is 250 Gray (Gy).
The table below shows the volumes of irradiated fresh produce exported from Australia into New Zealand from 2007–2010.
Irradiated fruit (tonnes) exported from Australia into New Zealand *
| 2007 | 2008 | 2009 | 2010 |
Mango | 228 | 261 | 585 | 460 |
Papaya | 13 | 1 | 0 | 0 |
Litchi | 10 | 21 | 57 | 33 |
TOTAL | 251 | 283 | 642 | 493 |
*Data obtained from Biosecurity NZ
Malaysia has approved irradiation as a treatment for exported Australian mangoes. The minimum dose required by Malaysia for the insect pests of concern is 300 Gy. For 2009 and 2010 Australia exported 263 tonnes of irradiated mangoes to Malaysia.
The United States Department of Agriculture (USDA) is considering access to the United States for Australian mangoes and litchi. Irradiation is expected to be the approved treatment; however at this stage there is no trade in any irradiated foods to the USA. The USDA is expected to establish a minimum dose of 400 Gy for their insect pests of concern.
Biosecurity Australia has approved irradiation as a treatment for mangoes imported from India; however, there are currently no mangoes being imported from India.