Aqueous Coatings

Food packaging inks and coatings compliance tends to cause much confusion and concern for those involved, from the raw material supplier to the printer or coating producer, to the end-use customer. Defined as an ink, overprint, or functional paper and packaging varnish, a wide variety of “coatings” are used on myriad food packages, including ready-to-eat, microwavable, take-out, refrigerated and frozen consumable items. However, there is confusion about the difference between direct and indirect contact versus direct and indirect additives, how specific applications are addressed in the regulations, and what options are available when establishing suitable safety and regulatory clearance for food packaging. In this article, we will discuss the applicable regulations and other considerations for determining the suitability of a coating for use in a food contact application.

When is a Coating a Food Additive?
A food additive is defined in the FFDCA as “…any substance the intended use of which results or may reasonably be expected to result, directly or indirectly, in its becoming a component of, or otherwise affecting the characteristic of any food including any substance intended for use in…packing…packaging…or holding food….” Based on this definition, under many circumstances printing inks and coatings that come into contact with food are considered food additives, and are therefore subject to premarket clearance by FDA. Two types of food additives recognized by FDA are direct additives and indirect additives. Direct additives are substances that are intended to become ingredients in a food product and therefore, are intended to be eaten. These include preservatives, flavoring agents, gums and anti-caking agents. Indirect additives are substances used in the processing, packaging, holding and transporting of food. These additives have no functional effect in the food, but may be reasonably expected to become components of food or to affect the characteristics of food. Inks and coatings often fit within this portion of the food additive definition.

In addition, the FDA recognizes three types of food contact. Direct Contact substances are those that directly contact food. Substances that might come in contact with food, such as on the outside of food bag or carton, are defined as indirect contact. Finally, incidental contact substances are those that rarely contact food and the contact is not purposeful or continuous. For example, food that contacts an extraneous part of a food processing machine where contact is not expected is considered incidental.

There often is confusion with the terms “direct additive” and “indirect additive.” Printing inks and food packaging coatings may be indirect additives, and they may have direct, indirect or incidental contact with the food. This means that they are not intended to become a part of food, but they may in fact do so through some type of food contact. Considering the following regulatory definitions and exclusions helps to clarify the difference:

Migration Data. According to 21 CFR 170.3(e), food additives do not include substances that do not migrate to food. It states: “If there is no migration of a packaging component from the package to the food, it does not become a component of the food and thus is not a food additive.” Thus, if there is acceptable data to show that a substance does not migrate to the food, FDA premarket clearance is not required. These data may be obtained in a variety of ways, from simple calculations to conducting migration studies using food-simulating solvents.

Functional Barriers. Often, a food packaging supplier will mention that a functional barrier excludes substances from becoming a component of food. This concept dictates that if a substance is not part of the food contact surface and is separated from the food by a barrier that prevents migration of the substance into food, then the substance is not a food additive and is excluded from the FFDCA definition of food additives. Establishing the existence of a functional barrier should include either migration testing or structural analysis using anticipated exposure conditions.

Housewares Exemption. Food packaging suppliers may rely on the “housewares exemption” to exempt their coating from FDA’s premarket clearance authority. There is no statutory or regulatory definition of a “houseware,” and FDA has not codified a housewares exemption. The definition of a “houseware” has evolved to include cooking utensils, paper cups and plates, plastic eating utensils and tableware. Since it is the responsibility of the producers of housewares to ensure their products are suitable for use with food, a safety determination that includes migration data is strongly recommended by FDA.

Indirect Food Additives Regulations. If a coating is reasonably expected to become a component of food, FDA regulates it, and prior to market introduction, one of these five clearances must be established:

• Substances permitted by an effective FCN. Unlike food additive petitions that resulted in CFR listing, only the submitter and its customers may rely on an effective FCN. Effective FCNs are published on FDA’s website. On rare occasion, FDA may require a food additive petition.

• Substances permitted by regulation in 21 CFR 175, 176, 177, 178.

• GRAS substances as determined by FDA. Many of these substances are listed in 21 CFR Parts 182, 184 and 186, or are published on FDA’s website. Sometimes these substances are only limited to the specific application for which the determination was made.

• GRAS substances as determined by qualified experts without FDA approval or notification. These are commonly referred to as GRAS self-determinations. FDA acknowledges in 21 CFR Part 182.1 that the list of GRAS substances is not exhaustive. This implies that manufacturers are free to make their own determination of safety. This approach, when done thoroughly, includes the depth of chemistry and toxicology data required as part of the FCN process.

• Prior sanction substances or substances that were approved for use before the FFDCA in 1958. The prior-sanctioned status of a substance is a straightforward determination that depends solely on the existence of an appropriate pre-1958 letter from either FDA or the U.S. Department of Agriculture (USDA).

21 CFR 170.30(6)(g) states: “A food ingredient that is not GRAS or subject to prior sanction requires a food additive regulation promulgated under Section 409 of the Act before it may be directly or indirectly added to the food.” Thus, a substance essentially becomes a food additive only if it fits into one of these categories.

Good Manufacturing Practices (GMPs).

As mentioned in 21 CFR 174.5, there are GMPs that apply to indirect food additives, which also should be considered. In particular, GMP guidelines require that the quantity of indirect additive that is used is not more than is reasonably required to accomplish the intended physical or technical effect in the food contact article. The substance must be of a suitable purity for the intended use and must not impart an adverse taste or odor to a food product. Several of the CFR sections contain references to quality assurance tests, such as 175.300, 175.320 and 176.170. It should be noted that these tests are less rigorous than the testing required for a FCN.

Regulations Applicable to Inks and Coatings
21 CFR has two parts that directly apply to many inks and coatings, Parts 175 and 176. The former, Part 175, Indirect Food Additives: Adhesives and Components of Coatings, includes four regulations with broad utility. These are

• 175.105: Adhesives for use as components of articles intended for use in packaging, transporting or holding food.

• 175.125: Pressure-sensitive adhesives for use as the food contact surface of labels and/or tapes applied to food.

• 175.300: Resinous and polymeric coatings intended as the food contact surface of articles intended for use in producing, manufacturing, packing, processing, preparing, treating, packaging, transporting or holding food. These are coatings that must be continuous coatings and, in many cases, may be crosslinked.

• 175.320: Resinous and polymeric coatings for polyolefin films. This lists substances that may be used as continuous coatings over polyolefin films listed elsewhere in the CFR.

Part 176, Indirect Food Additives: Paper and Paperboard Components, includes many regulations, two of which are of general interest to ink and coating applications for food packaging. Substances identified in these regulations may be safely used as components of the uncoated or coated food contact surface of paper and paperboard intended for use in producing, manufacturing, packing, processing, preparing, treating, packaging, transporting or holding of food. Part 176.170 applies to surfaces exposed to aqueous and fatty foods. Part 176.180 applies to surfaces exposed to dry foods.

The regulation in Part 176.170: Components of Paper and Paperboard in Contact with Aqueous and Fatty Foods, is divided into two sections. Section (a)(5) contains a list of substances that may be used without meeting quality assurance tests, as long as they follow the limitations mentioned in the section. While this is a long list, the substances listed have limited use in ink and coating applications. Most of the substances are for use in papermaking or to achieve specific paper properties. Section (b)(2) contains a list of substances that may be used, but that also must meet the quality assurance tests mentioned in Paragraph (d) of this section. These tests require that the extractives do not exceed 0.5 mg/in2 of food contact surface. For various food types and temperatures, there are different solvents and extractive conditions to model the application. Tables detailing both food types and conditions of use are found in this regulation at www.cfsan.fda.gov/~rdb/opa-fcn3.html.

Also of interest is Part 176.180, which addresses components of paper and paperboard in contact with dry food. Dry foods are Type VIII and IX foods as mentioned in Table 1 of 176.170. Substances listed in this regulation are not required to meet quality assurance test limits.

Determining FDA Status
Coatings and inks manufacturers and food packaging purchasers can take several steps to gather information to determine whether substances are considered food contact or additives, or not. First, the substrate identity (paper, polyolefin, polyester, etc.) of the substance should be determined, and then the use conditions (microwave cooking, room temperature, etc.). Next, food types to which the coating may be exposed should be identified. For general purpose applications, such as paper plates, this will include all food types. The supplier of the food contact substance should provide information on FDA clearances for each coating ingredient. If they cannot supply this information, the coating manufacturer should be very cautious about using the ingredient.

In addition, the presence of a functional barrier between the coating and food will help determine its proper application and use. If an acceptable functional barrier exists, the coating is prevented from migrating to food. Therefore, it is not reasonably expected to become a component of food, and is not subject to regulation. In the absence of a functional barrier, the next step is to review the substrate, use conditions, and food types and determine if all components are permitted for use under these conditions. If they do not conform, or if the restrictions are not acceptable for the application, the coating must either be reformulated with substances that are acceptable, or migration studies must be conducted to determine safety.

Migration studies should be performed as described in FDA’s chemistry and toxicology guidance documents to assure that the testing is acceptable for supporting a safety determination. If there is no migration, the ink or coating does not become a part of the food, under the test conditions, and is not a food additive. At this point, the coating manufacturer has two options: File a FCN with the FDA, or if a coating substance(s) is extracted, take actions to determine the potential exposure. If the exposure is low, the manufacturer can either file a FCN or make a GRAS self-determination. If too much substance is extracted, the ink or coating ingredient is not appropriate for the intended application and should not be used.

For an in depth look at Food Packaging Inks and Coatings as they relate to compliance please visit the FDA’s website.

Article written by By Lisa Barrientez and Paul Strege and published by Food Safety Magazine