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Listen to this siteWednesday 18 June 2003
This research project investigates the migration of chemicals from inks, and associated coatings, to food.
Study Duration : October 1999 to December 2001
Contractor : Central Science Laboratory
Printing inks and associated coatings have traditionally been applied to the outside of food packaging. Printing can provide information about the product, including appearance, ingredients listing, nutritional content, best-by and display until dates, storage instructions, preparation instructions etc. With the fierce competition which exists in the food marketplace, manufacturers and retailers look for new ideas to ensure their products outsell those of their competitors. One commonly used tool is some form of ‘promotion’. This may be a free gift in the pack, a competition with prizes or a simple ‘open and win’ promotion. For packs with a large surface area, these promotions can generally be printed on the outside of the pack. For small volume items such as confectionery bars, however, there is limited space on the pack exterior and it is becoming more common for promotions to be printed on the inside or for a printed enclosure to be placed in the pack.
The use of direct contact printing inks (inks used on the inside of food packaging in direct contact with the food) is likely to increase. The EU has not yet legislated in this area and, although the Council of Europe is compiling a resolution on printing inks, it specifically does not apply to direct contact printing inks. There is considerable evidence that chemical migration can occur from packaging materials to food. That manufacturers are now printing on the direct food contact surface raises obvious questions – what chemicals are used, could they migrate to the packaged food and, if so, are any migration levels of interest? These questions were addressed in this project.
Inks and coatings were obtained from the inks industry and were analysed to identify the chemical compounds present and to estimate their concentrations. Data on formulations and applications was obtained and used to estimate the potential migration of each of the compounds, based on the level of ink application, the area potentially in direct contact with food, and a worst-case assumption of 100 per cent migration.
The use of direct contact printing inks in retail applications was assessed via industry contacts and retail outlets. The main use of direct contact inks in the UK was found to be ‘open and win’ style promotions on confectionery packaging. Only one packaging sample was obtained throughout the duration of this project from a non-confectionery product, which was the use of direct contact ink on the lid of a yoghurt carton. Manufacturers of direct contact inks in the USA suggested other applications but no examples were located in retail outlets in the UK.
Seven different printed packaging materials, which had inks on the food contact surface, were obtained from industry or from retail outlets. Six were confectionery wrappers (two industrially supplied reels of wrapper intended for the confectionery market that had not been in contact with food, four obtained from retail purchases) and one was the lid of a yoghurt carton. They were analysed to determine the chemical composition of the printing inks. From the results obtained the worst-case migration potential was calculated.
Analysis of solvent extracts of the inks and lacquers used in direct contact printing inks has detected a number of compounds, which have the potential to migrate into foods. The identity and semi-quantitative concentration of these compounds in these raw materials were derived and the worst-case migration potential of these compounds was calculated.
No compounds detected in these materials had the potential to migrate above their respective specific migration limit (SML) taken from the plastics legislation which has been used as a presumptive standard by some in industry. For substances that do not have an SML, a level of interest was set at 10 parts per billion (10 microgrammes per kilogramme food) and any substance that had a worst-case migration potential above this level was considered in further detail. Of the ingredients identified that did not have an SML this level of interest was exceeded by 2-e thylhexyl acrylate. It had a worst-case migration potential of 16 parts per billion when assuming 100% inclusion in the printed material and 100% migration from the printed material into the foodstuff. Since the level in a printed packaging material would be attenuated by polymerisation and evaporation of this reactive monomer and since migration to the foodstuff would in all probability be less than 100%, then the level of 2-ethylhexyl acrylate would probably not exceed 10 parts per billion in a packaged food.
Solvent extracts of the inks removed from the packaging materials were analysed. The substances present were determined and the worst-case migration calculated for each substance. The highest migration potential calculated (320 parts per billion) was for acetyl tributyl citrate (ATBC) present in one of the industrially-supplied wrappers. A restriction of 5 milligrams/kilogram for food is given for this compound in the Synoptic Document. It is a plasticiser commonly used in printing inks.
None of the compounds detected in the inks and coatings supplied by industry had the potential to migrate above 10 ppb, the level of interest. None of these compounds were detected in the packaging materials included in this study. Some of the substances detected in the ink applied to the food contact surface of the packaging materials were not detected in the ink formulations supplied by industry. The most likely reason for this is that the substances originated from the outside printed surface of the wrapper and had set-off onto the direct contact ink whilst the film was on the reel. This is particularly so in the case of the reel of confectionery wrapper discussed above which had been stored for some time prior to analysis.
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 (020 7276 8181/8182 or at library&info@foodstandards.gsi.gov.uk ).
See Also
An assessment of the migration potential of inks used on packaging and in direct contact with foodstuffs. E. Bradley et al., Manuscript in preparation for submission to Food Additives & Contaminants.
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Email
: science@foodstandards.gsi.gov.uk
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