These are an an array of questions which, in the food packaging sector, is not all that easy to answer. The global regulatory situation is a very complex one, and there is no such thing as official approvals of printing inks. The parties involved must be respectful of a number of rules and regulations.
This article describes, from an international perspective and a practical standpoint, the applicable stipulations and the obligations and responsibilities of the ink manufacturer and the packaging printer.
1. What Rules Apply for Printing Inks for Packaging?
In other manufacturing sectors, the use of certain substances and auxiliary agents is either approved or prohibited. In the case of printing inks and varnishes, the situation is much more complex. There are no official approvals of substances for printing packaging materials, although a wide variety of legal regulations are in force regarding substances that come into contact with foodstuffs.
In Europe, the Framework Directive 89/109/EEC dealing with materials that come into contact with foodstuffs is decisive for the packaging. (Packaging for pharmaceuticals is normally dealt with at the same time as foodstuff packaging.)
The directive refers to the packaging as a whole, regardless of composition and processing. In addition to the actual packaging material (paper, cardboard, plastic or metal), the adhesives, coatings, varnishes and printing inks are also covered by the directive or by national laws of EU countries.
The U.S. has a legal framework provided by the Food and Drug Administration (FDA). Essentially, FDA regards as an indirect food additive any substance that may be reasonably expected to migrate and “become a component of the food.” Printed inks or coatings not intended for direct food contact may, in principle, contain potential indirect food additives.
In addition to the legal frameworks named above, a number of more detailed laws regulate the contact between packaging materials and foodstuffs, e.g. the European plastics directive 2002/72/EC (codified former directive 90/128/EEC) and the American FDA paragraphs 175 to 177 concerning plastics, paper and coatings which come into contact with foodstuffs.
These guidelines and the laws of individual European countries (such as France, the Netherlands, Italy and Germany) contain so-called “positive lists” of substances which have been evaluated, i.e. subjected to exacting and expensive toxicological tests. Materials and coatings that will come into direct contact with foodstuffs are approved only when they contain solely those substances that have been included in the applicable positive list. In the case of many substances which can migrate, either the permissible quantity in the packaging material or a migration limit has been specified, i.e. the amount that may transfer to the foodstuff is limited.
For printing inks and varnishes, there are actually no positive lists and no detailed regulations per se. This makes sense, because inks are not intended for direct contact. The absence of specific regulations does not, however, mean that no action is necessary. For example, the Council of Europe plans to issue a resolution concerning printing inks in the coming years. The contents of this resolution, however, are not yet concrete, though a central issue will certainly be the potential migration from printing.
2. The Non-Migration Principle
The principle of paramount importance in the aforementioned general guidelines which are recognized worldwide is that no substances may be transferred to the foodstuffs unless they have been officially approved and/or until it has been proven that their migration is not harmful.
This universal non-migration principle is in effect equivalent to a prohibition of internal printing of foodstuff packaging with standard printing inks, as only those materials composed exclusively of officially approved substances may come into contact with foodstuffs.
The non-migration naturally applies for the outside or the sandwich printing as well because it is also a part of the overall packaging. For example, under FDA rules, the justification is required that ink components are not “indirect food additives.” Therefore they must not become part of the food. Migration from external printing may potentially become an issue when printed packaging material is rolled up or stacked and the exterior of the package is in direct contact with its interior for a relatively long period of time.
Migration can also take place in the case of packaging materials with poor barrier qualities (e.g. paper and polyethylene or when wet or fatty materials are involved). Furthermore, even if they do not come into direct contact with the packaging, dry materials (e.g. cookies and chocolate) can absorb volatile substances present in the air space, which is usually closed off, in the absence of an effective barrier. Substance migration can also negatively affect the taste of the foodstuff.
3. ‘Good Manufacturing Practice’ in the Manufacturing of Printing Inks
If it is necessary for the packaging as a whole (i.e. including the print) to fulfill the strict requirements relating to migration, then the utmost diligence should be exercised in the very development and formulation of the printing inks. Printing ink manufacturers should be able to inform their customers as to which of their inks and varnishes are suitable for use with food packaging.
Since the non-migration principle and the various impositions relates only to primary food packaging (and the equivalent pharmaceutical packaging), printing ink manufacturers naturally offer a range of other ink series fit for general packaging of a lower level of sensitivity. As a consequence, they are dependent on their customers specifying exactly when the inks they order are intended for use with food packaging.
As an international manufacturer of printing inks for food packaging, SICPA has formulated “good manufacturing practice” principles for its branches in 38 countries worldwide. These principles are intended to provide the assurance that the ink formulations are analyzed regularly for conformance with the regulations in force, and that the inks and varnishes are developed and offered to customers in keeping with binding standards.
SICPA started from the “Good Manufacturing Practices for the Production of Food Packaging Inks,” issued by the European Printing Ink Associations CEPE in 1999. Since these principles are interesting not for the customer alone but for the end user as well, the most essential checks which embody SICPA’s “good manufacturing practice” are listed below:
1. In the selection and use of raw materials we monitor that recognized purity stipulations are strictly observed. That means that, as an example, the maximum contents of toxic heavy metal, aromatic amines, polychlorinated biphenyls, polycyclic hydrocarbons and dioxins are respected.
2.We select the raw materials and examine the formulations for minimum possible odor emissions, thereby affording sensorially optimized prints.
3.We guarantee that no raw materials are used for manufacturing its products that are contained in the CEPE exclusion list. We also monitor that in ink and varnish production, none of these substances can occur. In addition, the printing inks are formulated such that the user is able to produce prints which are free of substances contained on the exclusion list. This CEPE document prohibits substances which are toxic, carcinogenic, mutagenic and toxic for reproduction pursuant to hazardous material directive 67/548/EU and other elements and compounds which are objectionable in terms of their environmental compatibility.
4.In the formulation of recipes we orient ourselves wherever possible on recognized positive lists, e.g.:
• BGVV recommendations (Germany)
• §§ 175 - 177 (Resinous and polymeric coatings and other chapters) of the FDA (Food and Drug Administration in the U.S.) regulations.
• “Brochure 1227” (French legislation on packaging).
5.In the manufacturing of inks and varnishes for food and pharmaceuticals primary packaging, we examine whether the materials printed with such inks have the potential of coming into conflict with migration limits as set forth i.a. in the following official rulings:
• Plastics directive 2002/72/EC and revisions (as per 6th revision directive 2001/62/EC).
• Resolution AP(96)5 of the Council of Europe on surface coatings which are intended for use in contact with food.
We also observe the working document “Synoptic 7,” 2002 edition, which was compiled on the basis of general directive 89/109/EEC and which is not legally in force, but which does contain both the regulated substances as well as the substances contained in the plan with their limit values.
6.We guarantee that the inks and varnishes are manufactured exactly according to the prescribed recipes and without harmful impurities.
7.We offer the packaging printer and the end user farthest-reaching support in achieving compliance with all regulations and stipulations. We inform customers on the intended use or on eventual limitations of use, and direct his attention to the parameters to be monitored.
4. ‘Good Manufacturing Practice’ of the Packaging Printer
Under the auspices of “good manufacturing practice,” an entire array of “due diligences” are under the control of the printer and, a step further, of the users of food packaging. These are the ones who carry the legal responsibility for the harmlessness of the packaging which ensues in their activities from the packaging material and the wet or uncured ink.
The six recommendations listed below for printers of food and pharmaceutical packaging are taken from a publication of the SICPA Group.
1. No direct contact between the printed ink and the food.
The printer should ensure that no direct contact can occur between the printed surface and the food at any point of the packaging. The non-migration principle which has found acceptance in general statutes worldwide virtually prohibits the printing of standard inks on the inside of food packaging. The few exceptions to this prohibition concern only very sophisticated niche printing inks, which are specially formulated for direct contact with food.
2. There must be a “functional” barrier.
The printer should ensure the presence of an effective barrier between the ink film and the food (e.g. suitable film or aluminum foil). The stipulation of a barrier is the effect of the non-migration principle which with regard to its action relates to the packaging as a whole, i.e. to the outside printing as well.
For instance, the overvarnishing of inside printing does not automatically form an adequate barrier. Paper and polyethylene also have poor barrier characteristics, in particular in the case of packaged products which are wetting or greasing. In addition, high temperatures, particularly in a wet environment, promote the passage of molecules which are capable of migration via the air or through unsuitable plastic films.
This circumstance has to be given special consideration in the case of packaging for sterilization and food packaging for oven heating.
3. Minimization of migration by the selection of the right printing ink.
If printed packaging material is rolled up or stacked on or inside one another, the printed outside surface will be in close contact with the inside of the packaging for a prolonged time. Migrating materials from the printing ink may possibly deposit themselves on the inside, and can subsequently come into direct contact with the food. This is the case if inks which have not been approved for use containing migratorially or sensorially active components – small, mobile, soluble molecules – are used for this purpose.
A deliberate selection is required even in the case of dry foods (e.g. cookies, chocolate, tea, tobacco). Otherwise, these packaged products may absorb volatile substances from the printed ink via the otherwise closed air space.
4. Requirements on the packaged product, and on use by the customer.
The printer is required to take into account not only the substrate, the printing ink and the printing method, but also the further processing up to the finished packaging, the characteristics of the packaged product and the use of the filled packaging by the consumer.
If e.g., packaging is printed which is to be sterilized together with the packaged product or which is heated up by the consumer in a baking/microwave oven, the printer is advised to use printing inks with the appropriate specifications. This also applies for packaging of fats, meat, ready-cooked meals, fruit juices and the like. Such packaged products have a high extraction potential, meaning that they literally promote diffusion and mixing with migratory substances.
Non-resistant inks which are heated to temperatures in excess of 200°C or treated with hot steam or hot water may give off migrating substances, bleeding pigments or harmful breakdown products which in turn find ingress into the food.
In all these cases, the printer is advised to take advantage of the advisory services of the printing ink supplier. As the first consideration, it is important to select colors of pigments with as low a migration tendency as possible. Just as there are colors made from light-resistant and non-light-resistant pigments, identical color shades are also available with different migration potentials (e.g. resistance to fat, acid, sterilization and pasteurization).
5. Check of drying and curing.
The printer should ensure that the printed ink is as solvent-free as possible, or that UV and offset inks have completely cured according to the standards adopted for use in the respective branch. This practice also includes regular inspection of the UV radiators. Failure to observe this consideration will pose the risk of ink set-off in the roll or in the stack, or of a sensorial and migratorial effect on the food.
6. Due diligence of the printer to provide information.
It is advised that the printer should regard it as his due diligence to obtain the pertinent information from the packaging manufacturer, respectively, from the end user relating to the purpose for which the packaging is intended and how it is used. The objective has to be not only the “technical” quality, but also the migratory inertness of the packaging up to the consumer. If he fails to do this, in the worst case he is risking the recalling of the packaged food from the market.