PART 15 OF OUR STEPLADDER SERIES ABOUT FOOD PACKAGING REGULATION
Read this and look bright.
One of the most common sources of confusion when it comes to the US Food and Drug Administration's (FDA) regulation of printing inks is... the absence of a single food additive regulation specific to the use of printing inks! Unlike colorants for polymers, which are explicitly regulated in 21 C.F.R. § 178.3297, printing inks applied to the outside of food packaging are instead often evaluated using many of the concepts discussed in our previous StepLadder Series articles, including the "Functional Barrier" principle (when applicable), the "No Migration" position, and of course, FDA's General Safety Clause and Good Manufacturing Practice (GMP) requirements.
The chemical composition of a printing ink can range from simple (e.g., a colorant) to complex (e.g., colorants, carriers, additives, processing aids, and more), depending on the desired technical properties and intended use of the finished product. Certain printing inks, for example, may be suitable for printing on materials that hold food at room temperature or below, whereas others may be suitable for higher-temperature applications, such as cooking or microwave use. Printing inks also may contain additives and processing aids that further impart desirable qualities such as clarity, shine or reflectivity, thereby enhancing the potential appeal to consumers. These substances must be assessed from a regulatory compliance standpoint in addition to the primary pigment(s) themselves.
In many cases, printing inks are applied to the outside of a food-contact material or article. Common examples include graphics, date codes, bar codes, and other identifying information. While printing inks are not as commonly applied to the interior of food-contact materials or articles, they may still be present on the food-contact layer as a result of off-set from previous contact with the non-food-contact side during manufacture of the printed surface (e.g., during rolling of a printed film before the film is formed into a bag, or during stacking of containers or articles). Therefore, the safety – and ultimately, the suitable FDA status – of the printing ink should be evaluated both from the perspective of intentional exposure from the outside of the packaging (if any), as well as unintentional exposure from the off-set that may occur during manufacturing and processing. The former is a question of regulatory compliance, whereas the latter is a question of GMP and suitable purity.
When assessing the suitable FDA status of a printing ink, one should first consider the intended use of the ink. For example: (1) what is the printed substrate composed of; (2) how much printing ink is applied to the substrate; and (3) what is the composition and use level of the printing ink itself? We then consider factors such as the Food Types and Conditions of Use that the packaging containing the printing ink will be subjected to when the ink is used as intended. For both intentional and unintentional (off-set) analyses, the volume of food held inside the container is an important consideration when determining the upper-bound potential migration of – and exposure to – components of the printing ink.
The status of the finished printing ink and its individual components is necessarily evaluated on a case-by-case basis, though it may be possible to initially group categories of substances into a broader assessment based on use level and other quantitative factors when evaluating the safety of potential exposures from a toxicology standpoint. Depending on the specific composition and intended use of the ink, certain strategies, such as upper-bound (100%) calculations or diffusion modeling sometimes may be preferable to migration testing. Finally, given the potential complexity of printing ink formulations and the proprietary nature of such information, the use of an independent third-party like Steptoe's Global Food Contact Materials Team may be helpful to collect, organize and evaluate these compositions under appropriate confidentiality provisions with upstream suppliers.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.