Preservatives are synthetic or natural chemicals added to food to extend its shelf-life. They prevent or slow down the growth of micro-organisms such as mould, yeast and bacteria that may spoil food and cause severe illness in people. The most widely used preservatives are sulphites (including sulphur dioxide), sorbates (including sorbic acid), and benzoates (including benzoic acid).
Preservatives are listed in the ingredients list. They appear as ‘Preservative’ followed by their name, or their unique international code number eg, Preservative (sorbic acid) or Preservative (200).
Preservative code numbers:
- sorbates - 200 to 203
- benzoates - 210 to 213 (216 and 218 also contain benzoate but are known as parabens)
- sulphites - 220 to 225 and 228
Numbers are used on labels as they take up less space and avoid possible confusion with additives with similar names.
Preservatives are only allowed in specified foods where they are needed. They are permitted at the lowest level possible to achieve the desired preservative effect. This level must be less than the Maximum Permitted Level (MPL). The MPL is the amount of each chemical that should not normally be exceeded if good manufacturing practice is followed. Keeping preservative levels below the MPL also ensures there is no significant risk to consumers.
MPLs are legal limits, listed in the Australia New Zealand Food Standards Code. Food Standards Australia New Zealand (FSANZ) is responsible for this Code.
Food Standards Code (External)
The Maximum Permitted Level (MPL) sets the amount of preservative allowed in food. There are calculations on how much preservative is safe to eat each day from all the likely foods in our diet containing that particular substance. This level is known as the Acceptable Daily Intake (ADI). The ADI level is considered safe for us to consume every day, and throughout our lives, without causing adverse effects. It is calculated allowing a considerable safety margin.
The ADI for people is at least one hundred times lower than the dose fed to animals, where the animals showed ‘no adverse (toxic) effect’ even though they consumed that dose, on a daily basis, over their normal lifetime.
The ADI is determined by a committee of international experts convened by the World Health Organization and the Food and Agriculture Organization. The committee is called the Joint Expert Committee on Food Additives (JECFA).
On rare occasions, people may react to sorbates and benzoates. However, sulphites may cause asthma-like symptoms in those who have asthma or chronic allergic conditions.
If you are allergic to sulphites take care to read the label on products so you can avoid consuming them.
Patient information on allergy disease (External)
Results from MPI and Food Safety Australia New Zealand (FSANZ) studies into the dietary exposure to sulphites, sorbates and benzoates in Australia and New Zealand, combined with snapshots of everyday diet, showed our food contained safe levels of preservatives. Apart from a few high consuming individuals who eat very large amounts of foods containing preservatives, preservative consumption was low.
All population groups, even high consumers of sorbates had an intake level well below the Acceptable Daily Intake (ADI). However, a small number of children and youths had eating patterns, which meant they were consuming above the ADI levels of benzoates and sulphites.
While high dietary exposure to sulphites and benzoates are not associated with adverse health effects in people, FSANZ has decided to conduct a review of these in the Australian and New Zealand food supply. Appropriate risk management strategies will be considered if necessary to limit the exposure to sulphites and benzoates for certain age groups. The outcome of the review is expected mid July 2008.
We support the review being undertaken by FSANZ and will be sharing New Zealand information based on recent dietary intake figures. We will also continue to monitor the situation in New Zealand.
For information on the studies conducted by MPI and FSANZ use the links below.
Research shows sausages are the main food contributing to the exposure to sulphite for young people, with similar contributions from soft drinks and cordials, hamburger patties and dried apricots. For adults, wine and beer are also important. Orange juice, margarine and baked goods (cakes, muffins, pikelets and crumpets) are our main source of sorbates. Benzoate consumption is almost solely from soft drinks.
Remember that preservatives are used in food to reduce the growth of harmful pathogens that can cause severe illness in people, and they maintain the quality of food and minimise spoilage.
Overall, given the large safety margin built into Acceptable Daily Intake (ADIs), our exposure to preservatives in food is unlikely to be a health risk except if you suffer from an allergy to sulphites.