A03027 (FS2255): Determination of the potential for transfer from secondary packaging to foods and development of guidelines to reduce transfer to levels of no concern

Study Duration: October 2000 to April 2004

Contractor: King’s College London

Considerable attention has been paid to the transfer of substances from primary packaging materials to foods i.e. from the packaging material which is the immediate layer surrounding a packaged foodstuff. Less attention has been given to so-called secondary packaging i.e. materials used for packaging but which are separated from the food by a layer of primary packaging. Examples of secondary packaging are the outer cartonboard box of a breakfast cereal, where the cereal is packaged in a plastic wrapper (primary packaging) inside the box; or a corrugated board box used to transport packets of biscuits from the manufacturer to the retailer.

Currently, only primary packaging materials are tested to any great extent to ensure their safety-in-use in terms of transfer of substances. The general assumption is that there will not be significant transfer of substances from secondary packaging to food and hence, that chemical testing of the type applied to primary packaging is not required. If there is a potential for transfer, those involved in the packaging chain (packaging manufacturers, importers, food producers, distributors of food, food retailers, caterers etc.) need to be made aware of this so that they can take appropriate action.

A series of studies was carried out to evaluate the potential for transfer of substances from secondary packaging to foods, to identify the factors which are important in transfer and to develop guidelines for use by those involved in the food distribution chain to minimise transfer.

Transfer to foods from secondary packaging was measured by incorporating substances (surrogates) into secondary packaging so that there would be a ready source of substances whose transfer could be measured. Surrogate substances were used because substances already present in packaging materials vary between different types of material both in terms of types of substances present and quantity. The deliberate incorporation of substances maximised the information obtained from the studies and permitted trends to be identified which can be applied more widely to packaging materials other than those examined in the research.

Corrugated board boxes and cartonboard boxes were used as secondary packaging materials. Foods packaged in primary packaging were then stored for up to 200 days in this secondary packaging. Crisps, savoury biscuits, sweet biscuits, dried fruit, breakfast cereal, chocolate coated confectionery and choc-ices were the foods stored. The foods were removed from the packaging at known time periods and analysed to determine whether the incorporated substances had transferred and, if so, how much had transferred.

More volatile substances transferred more readily than less volatile ones and transfer increased with increasing storage time. The nature of the primary packaging material was important - some materials delayed transfer more than others. Transfer was lower to foods packed in multipacks compared to the same foods in single packs. Percentage transfer varied from 0 to 100% for the food/packaging/storage conditions studied. Transfer of substances also occurred to frozen foods (-20°C storage).

A further series of studies was carried out to examine the factors affecting transfer. Substances were again incorporated into cartonboard and transfer to an adsorbent material measured varying the following parameters:

• Time and temperature of the experimental conditions.
• Nature of the primary packaging placed between the secondary packaging and the adsorbent.
• Distance between primary and secondary packaging.
• Concentration of substances in the secondary packaging.
• Humidity of experimental conditions.
• Type of foodstuff.

This series of experiments confirmed the findings of the transfer studies to foods with respect to volatility, storage time, influence of type of primary packaging and transfer during frozen storage. It was also shown that transfer increases with increasing temperature and with increasing concentration of substance in the secondary packaging material. It was found that humidity could affect transfer, particularly for nylon. Also in this project the results indicated that the relative effectiveness of primary packaging materials in terms of reducing transfer of substances from primary packaging was poly(ethylene terephthalate (PET)>nylon>poly(vinylidene) (PVdC)-coated poly(propylene) (PP)>metallised PP/PP laminate>PP>paper. It was also found that volatile substances could transfer across a 2 cm gap between primary and secondary packaging.

The studies indicated that there is a 'cut-off' threshold in terms of transfer. Substances with volatilities above this threshold did not transfer at ambient temperature.

The research showed that there can be chemical transfer from secondary packaging to foods. Factors important in this transfer have been identified and have permitted guidelines to be drafted on ways to minimise transfer of substances from secondary packaging to foods. These guidelines are aimed at those involved in the manufacture of materials to be used as secondary packaging for foodstuffs and those involved in the supply of food for human consumption.

Final report is available from the FSA Library and Information centre. To obtain a copy, please contact the Enquiry Desk, Dr Elsie Widdowson Library and Information Services, Food Standards Agency tel: 020 7276 8181/8182 or email: infocentre@foodstandards.gsi.gov.uk

Contact: For any enquiries concerning this research project, please contact the relevant Programme contact or e-mail: science@foodstandards.gsi.gov.uk