The calls for measures against mineral oils in inks have been criticized by ink producers in Europe, who for several years have been encouraging customers to switch to low migration or vegetable oil-based inks in food packaging.
“It is important to recognize that there are a number of potential sources of mineral oil in food packaging, including the substrate, process lubricants, printing inks, secondary corrugated packaging and even the food itself,” said Felipe Mellado, Sun Chemical’s chief marketing officer.
“This is a multi-industry infrastructure issue involving the recycling, newspaper and packaging industries, and multiple options are available to resolve the current concerns, outside of ink reformulation,” he added.
Concerns Over Mineral Oils
Mineral oils can endanger human health because they can contain aromatic hydrocarbons, which are carcinogenic, and also short-chained saturated hydrocarbons, which can be easily absorbed by the body and can accumulate in several organs over a long period. Paper makers and paper and board packaging converters have been stepping up their efforts to lower the content of mineral oil in food packaging.
In December, the Confederation of European Paper Industries (CEPI) and the International Federation of Paper and Board Converters in Europe (CITPA) announced a commitment to phase out the use of printing inks with mineral oils for printing paper and board packaging.
The two associations claim that levels of mineral oil in products of the European paper-based packaging industry had been reduced by up to 90 percent “in some cases” over the past two years.
Paper producers and paper and board converters have already successfully eliminated or reduced to safe levels dibutyl phthalate (DiBP), a plasticizer in adhesives which had been migrating from packaging materials in potentially dangerous amounts into packaged foods.
“We are confident that the reduction will be visible in the same way as the European wide phase-out of DiBP in adhesive applications was for paper-based packaging a few years ago,” explained Jori Ringham-Beck, CEPI’s director of recycling, product and the environment.
The impact of the CEPI/CITPA commitment will need to extend to the paper producing and paper and board conversion sectors in the packaging chain to be fully effective.
“It is only part of the solution,” said Mr. Ringman-Beck. “We are hoping that it will lead to the eradication of all the root causes of the problems – one of which is mineral oil in publications like newspaper, which is recycled into paper for use in packaging. The solution to that may be development of new printing technologies in publishing including the reformulation of inks, which we appreciate will take some time.”
The task, however, of removing mineral oils from inks in both the packaging and publications sector will be far tougher than the phase-out of DiBP.
Currently, the generally accepted safety limit for migrating mineral oils in foods is based on a study by an expert committee on food additives (JECFA) in 2002 set up by the United Nations’ Food and Agriculture Organisation (FAO) and World Health Organisation (WHO).
It recommended an acceptable daily intake (ADI) of mineral oils of 0.01 micrograms per kilogram (mg/kg) of body weight, which is calculated to be equivalent to a specific migration limit (SML) of 0.6 mg/kg of food.
For this limit to be reached in food, the maximum concentration of mineral oil, at the appropriate volatility levels, in recycled paperboard should be around 3 to 5 mg/kg. However, the average in unprinted recycled paperboard is around 350 mg/kg, according to figures from the Official Food Control Authority of the Canton of Zurich in Switzerland, one of the leading research bodies on food migration in Europe.
“To achieve the JECFA recommended levels, levels of mineral oil in recycled paperboard would have to be reduced by a factor of 100, whereas the DiBP phase-out was realized with only a five-fold reduction,” said Koni Grob, leader of the research team at the Zurich-based authority.
“Because mineral oil concentration in newspaper printing ink is much higher – etween 4 to over 20 times – more than 99 percent of the mineral oil in newspaper would have to be eliminated. It would be very expensive.”
Efforts to Reduce Mineral Oil Usage
Consumer product companies have started demanding that packaging suppliers provide certification that any recycled paper they are using has at least low levels of mineral oil, if not are free of it.
Within the European Union, there are currently no regulations which specifically stipulate adherence to the JECFA restriction equivalent to the migration limit of 0.6 mg/kg of mineral oil in packaged food.
The European Commission, the Brussels-based EU executive, has declined to draw up EU legislation on the matter despite demands by member states and industry groups that it take action.
As a result, the German government has decided to take the lead by issuing a draft regulation on mineral oil controls. While the limit for mineral oil saturated hydrocarbons (MOSH) would be 0.6 mg/kg as advised by JECFA, the one for mineral oil with aromatic hydrocarbons (MOAH) would be 0.15 mg/kg on the basis that aromatics make up on average 15 to 20 percent of technical grade mineral oils.
The problem of migrating mineral oils has been known for around 20 to 30 years, but it was thought that the oils would move only into liquid or fatty foods.
Two years ago, Mr. Grob’s research group found in a study of packaged dry food that their mineral oil content was 10 to 100 times higher than the JECFA safety limit.
Then in another study published last autumn, Mr. Grob’s researchers discovered that mineral oils in a corrugated board transport box contaminated the bottom packs of noodles in the container with 6.1 mg/kg of MOSH while having the capacity to adulterate all 10 packs in the box to a level of 10 mg/kg.
This study has heightened concerns in the packaging sector because it could mean that the mineral oil content of secondary paperboard packaging could threaten the safety of all types of primary food packaging, including plastic packs.
The study showed that the migration from recycled paper with five times less mineral oil than average still reached 4.9 mg/kg.
The printing ink in the study achieved the 0.6 mg/kg limit, but only after the mineral oil content had been decreased to 100 times less than conventional offset inks.
“We think the results of this study are very important because they show that if the German regulation on mineral oil content comes into effect with the JECFA limit, the use of recycled paperboard transport boxes with their current mineral oil levels will no longer be acceptable,” said Mr. Grob.
The option of replacing recycled with virgin paper in food packaging seems to be out of the question. The European paper-making sector does not have the capacity to handle such a large increase in demand, nor would an enormous hike in imports be sufficient to meet it. Currently, more than three quarters of paper and board in packaging in Europe has been recycled.
It has been suggested that two separate streams of recycled paper could be created. One would be for packaging paper, in which there would be more potential for removing mineral oils since they make up a relatively small proportion of the total content of the paper. The other channel would be for recycled publication paper.
But such reorganization would require radical and highly expensive changes in the collection and recycling infrastructure for paper recycling.
Hence the spotlight has fallen on the possibility of reformulating ink to reduce substantially or eliminating their mineral oil content by replacing it with vegetable oils.
Ink makers in Europe, particularly Sun Chemical, Flint Group and Siegwerk, have already reformulated their portfolios of packaging inks so that they can offer low-migration, vegetable oil-based products.
Any reformulation would have to be focused on graphics ink, in particular those for newsprint, which is being resisted by newspaper publishers. They argue that a switch to ink without mineral oils would be too expensive.
“In principle, if there was the demand from the newspaper industry for vegetable oil-based inks, the printing ink industry will be able to develop the inks and provide adequate supplies,” explained Martin Kanert, EuPIA’s executive manager. “There are no technological barriers, only a need for time to fully develop the inks.
“Existing graphics inks are safe if used properly and for the purposes for which they are intended,” Mr. Kanert added. “We always warn the paper and board converting sector and our customers in packaging that they should exercise caution when using recycled paper from the graphics sector. We tell them there will inevitably be non-food grade ingredients in the paper, which could migrate through the packaging unless other measures have been taken such as the application of functional barriers.”
In fact, barrier coatings are emerging as the most practical and possibly least costly solution to the problem of mineral oil migration.
“We’ve tested a number of polymer-based materials for barrier coatings, which work well,” said Mr. Grob. “The big challenge is to ensure the coatings adhere well to the inside surfaces of paperboard, which will require pre-treatment.”
European Editor Sean Milmo is an Essex, UK-based writer specializing in coverage of the chemical industry.