Human health and environment – two major issues for printing ink industry

Perhaps during the Arab Spring, the power of the social media was first felt. Media savvy leaders have now arisen like Narendra Modi, Vladmir Putin and Donald Trump, who know how to work with the social media and sometimes control its direction. So, how can social media impact printing inks industry and what is the preemptive response from ink manufacturers like Sakata Inx? In terms of the printing ink industry, two key themes will have major impact from the social media in future – human health and the environment.

Migration threat? Fact or fiction

Dr Konrad Grob, a global expert in packaging, has said, “There is not a single food compliance document for which compliance has been demonstrated. So the simple way is to cheat. Media has learnt this is a wonderful way to make a scandal.”

Is it true? For those like me who peer into chromatograms, we know that packaging material migrates but have little idea if it is all relevant toxicologically. Even simple polymers like polyethylene always have a degree of oligomers. It could be to the level of more than 60% of the polymer weight sometimes. A polymer with a molecular weight of >1000 Daltons is perceived as irrelevant to migration issues as it will not be easily absorbed and further it will be probably metabolically inactive. But this is not true of oligomers.

Of more than 5000 ink ingredients listed officially in positive lists, more than half have not been really tested. The usual rule says that those listed in a positive list in Category B have a limit of jut 10ppb. So who has cleared all the food packets?

The story is quite the same if we talk about mineral oils, especially aromatic oils (MOAH) used in secondary cellulosic packaging; a topic which the media has particularly latched on to. Aromatic hydrocarbons with three or more, non- or simple-alkylated, aromatic rings may be mutagenic and carcinogenic, and therefore of potential concern.

After the ITX scare UV too came under the scanner, ECMA says, “The member carton makers are recommended to stop the use of UV inks and varnishes – if they have ever done so – for primary food packaging, or to stop the use of the current UV inks and varnishes and to consider a switch to alternatives, which might have a cost impact, and of which validity has been proven by a third party assessment.”

Then there is the subject of NIAS (Non Intentional Added Substances). Some could be catalytic residues, some impurities and some could be deliberately added as a preservative within the substance definition of another material. So if we use TNPP as a secondary antioxidant in a plastic, then the plastic granule manufacturer may legally include it in the substance definition of the polyethylene. At the levels concerned, it would not trigger a GHS chemical classification, though as a food contaminant it would be a substance of concern. An important point here is that it could release nonylphenol as a metabolite which is an endocrine disruptor.

Work-in progress

So assessment is clearly work-in-progress. We hence need to communicate to the general public that reach is still yet underway albeit highly successful. Hence globally even today substances may not be fully assessed especially the critical smaller volume additives of a migratory nature. Food concerns really grew in the late 1990s. Some controls have been put in. But there is no clear case of compliance at the moment probably in any ink ever sold or ‘certified’. There are genuine Confidential Business Information concerns with ink companies. So unless a migration study is seriously discussed the ink manufacturer is reluctant to part

with a statement of composition other than saying that he has done due diligence to a battery of regulation.

Absolute and functional barrier

When one is talking about food migration, it is important to talk about the context of packaging. Glass invented several thousand of years ago provides an absolute barrier possibility. Tin can came into being in the 1900s. Recently, a tin can more than 100 years old was dredged up and the food was found to be perfectly edible. Of course there are coatings in the tin which do have a potential to migrate into food but there is little doubt that tin cans certainly have improved upon nature in terms of preservation lifespan of the food packed. Essentially these are examples of absolute barrier.

Flexible laminates however have the concept of a functional barrier and the food preservation is based on reasonable and foreseeable circumstances of use based on time. A printed paper cup which is often printed with offset ink is also a functional barrier. Such offset inks must be carefully chosen and the type is often referred to as being ‘low migration inks’. Finally we have hybrid aseptic packaging from companies like Tetrapak and Greatview which is a combination of plastic and paper, sometimes with foil.

One must not forget secondary packaging which often uses offset and UV ink. Here too controls of mineral oils, odorants and sensitizers are important.

How does the ingredient get across the functional barrier?

There are five possible ways for an ingredient to cross the functional barrier.

• Permeation of volatile substances: Some ingredients may give off slow formaldehyde release. Melamine formaldehyde and ketone-aldehyde resins are typical of them. In some cases such as soft gel capsules this may be a serious problem as the dissolution of the capsule is subsequently affected. In India several drugs of the type are stated to have dissolution problems.
• Diffusion of substances: A substance may slowly diffuse across the functional barrier. To simulate this one may use a combination of Fick’s law of diffusion to understand the kinetics and at equilibrium the Log Kow distribution constants between the different laminates.
• Set-off of substances during printing processes (Visible and Invisible): This may happen during winding of the reel. Since pigments are by and large insoluble, quite often the invisible set off exceeds the visible.
• Leaching of substances (involvement of the oily food perhaps): Called Class III migration also. Here an oil may extract out a substance in the laminate. Simulation of this type of migration is more difficult and may involve calculations involving Fat Reduction Factors under 10/2011/ec.
• Fortuitous surface set off (Visible/Invisible): A surface print may be licked off by a child or may come into contact with the food under usage such as butter touching the surface print.

Regulation of printing ink

In the late 1990s, the European Union more seriously began to examine food packaging especially the role of laminates in food packaging.

A key legislation issued is 1935/2004/ec or the framework law in the EU. The framework law simply says that the authorities may issue a number of laws to achieve a ‘basis for securing a high level of protection of human health and the interests of consumers’ but it may not envisage all circumstances present and future and hence the food business operator must have a ‘duty-of-care’ in terms of the visual, organoleptic and chronic toxic related situations that may arise from normal and foreseeable circumstances of use of packaging.

CMR and other exclusion criteria

A key clause in food packaging is the Delaney clause whereby all CMR substances in Category 1A and 1B (GHS system) are eliminated from deliberate use in any quantity. This has been expanded to an exclusion list of hazards by CEPE and EUPIA. It is like religion, there is no de minimus or excuse to deliberate usage.

Testing of migration in plastic and cellulosic based laminates

Legislation like 2002/72/ec and 10/2011/ec came through to deal with migration testing in plastic laminates. Similarly 2007/42/ec attempts to deal with cellulosic. Since one cannot test migration of packaging materials into real food, simulants and procedures were created to enable experimentation and analysis. For instance it is assumed that 1 kg of food can be packed into 6 dcm2 of laminate. Ingredients may have Specific Migration Limits depending on their level of concern.

Worst case calculations
Positive lists

Another key legislation was the Swiss Ordinance of the FDHA on Materials and Articles (817.023.21) of 23 November 2005 which introduced the concept of a positive approved list of additives, resin monomers, colorants and solvents to be used in printing inks. This was a prelude to a full positive list from the European Union ResAP (2005)2. The European Union Ink Association EUPIA also has a positive list which will guide future legislation. Positive Lists tell what can be used.

Negative lists

The Japan Printing Ink Makers Association introduced a negative list of substances that cannot be used by deliberation in printing inks called the Voluntary Regulation Concerning Printing Inks (Negative List Regulations). It tells you what cannot be used.

Before deciding on a migration test, a worst case calculation is normally performed. This assumes that all the ingredients in the ink enter the food in a total transfer. If there is still no danger to human health then all is fine. The important work in progress here is to have substances transferred from category B to category A in the positive list.

Substance purity

Two substances with the same registry numbers may have different regulatory profiles. They may include different additives within the substance definition. The ink manufacturer has a different positive list to that of a manufacturer making a plastic used in the context of food packaging. Nevertheless the ink manufacturer usually conforms to the same substance purity criteria as that demanded for food level plastic laminates such as under ResAP(89)1. The purity criteria is extended to colorants used in the ink as also other additives.

In silico methods

Risk and hazard models will be able in the future to predict a migration problem by in silico simulation. Models operate by Ficks diffusion law and thermodynamic distribution of the material between the layers of plastic laminates. Time and temperature also need to be factored in based on usage pattern of the particular item of food. Models in the future will become more robust once data becomes more available.

Some companies like Nestle have formulated their own compliance list where a high level of precaution is demanded.

Indian context

India has not yet implemented UN Global Harmonized System GHS so there is practically no definition on hazard. Virtually any material can be used commercially including research materials as there is no Inventory control.

There is a category of ink called’ vinyl’ in India and the use is extensive. Such ink was discontinued in most of the OECD some 30 years ago and in China in 2011 or so. The Toluene solvent retention is usually >>2mg/m2 laminate (‘Korea Standards and Specifications for Utensils, Containers and Packaging for Food Products’ October 2011(update)) or >>1.2mg/kg food (SML under 10/2011/ec).

It is a piquant situation in that though the framework law is vague on specifics it already has as a high degree of ‘duty of care’ (ref.: PREVENTION OF FOOD ADULTERATION ACT – 1954 & updates). Further some sections under the law are severe in terms of penalties.

Section 19 Indian Law (PREVENTION OF FOOD ADULTERATION ACT): ‘Sale of any adulterated or misbranded article of food a allege merely that vendor was ignorant of the nature (of the offence) under this Act. It shall be no defense in a prosecution for an offence pertaining to food to allege….’

Section 20: ‘Notwithstanding anything contained in the Code of Criminal Procedure, 1973, an offence punishable under sub- section (1AA) of section 16 shall be cognizable and non- bailable.’

Environment

The ink uses a terpolymer of vinyl chloride-vinyl acetate-vinyl alcohol. Since vinyl chloride polymers are involved, so perhaps care needs to be taken during incineration. Surjit Kumar Chaudhary, secretary, Department of Chemical & Petrochemical said in 2015 at a CII seminar in Mumbai that printed flexible packaging should be considered one of the more polluting aspects of industry. Having spent some time watching rag pickers, he noticed that printed flexible laminates were not easily suitable for disposal or recycle. This should be truer in case of laminates using the so called chlorine rich vinyl inks. In circular economy, projects such as Suwas of the European Union certain catalysts are used and it is suspected that these catalysts may be deactivated by such vinyl chloride based resins. In the circular economy, the effort is to remove the ink from laminates and recover the plastic.

The Supreme Court of India already has said: ‘we are sitting on a plastic time bomb’.

There is backlash against goods that have passed through the chemical industry. Some do believe that organic is the answer whereas others believe in products of ancient wisdom or advocated by a religious figure. In some locations food is often packed in newspapers in India in an effort to eliminate plastic. Inks used on Indian newspapers contain high levels of PAH and cannot be traded overseas into Europe under Restriction Law 76/769/ec.

If the industry does not realize public opinion, it may be seen as part of the problem not the solution. There is a possibility of Russian roulette. Somebody is going to get caught with perhaps toluene in the food. The petitioner is going to quote the WHO endorsed figure of 1.2mg/kg food. He will be cheered on by the media and the politician will also weigh in. A non bailable jail sentence is to be issued on the CEO and his clever collaborator, who made the food compliance certificate. However all will pray it is the ink manufacturer next door.

On a concluding note…

The ink industry needs to self regulate and can do so by forming an association parallel to that of the EUPIA. It can quickly issue a set of industry standards to exclude certain hazard categories, control toluene levels in film, restrict solvents like ethyl cellosolve, exclude plasticizers like ortho phthalates, ensure proper disposal of rhodamine dyes and control heavy metals. Key packaging types or key ink substances can be routinely tested for Overall Migration and Specific Migration Limits at neutral laboratories. In doing so it would do itself a favor by increasing viability on exports since the same product would be operating in the domestic.