Components of the Basic Resin

The StepLadder Series is a Steptoe publication focused on discussing food contact regulatory topics in plain language.

When it comes producing polymers, sometimes it’s good to get back to basics.

How does FDA Regulate Components of the Basic Resin?

Polymers Authorized Under the Code of Federal Regulations

FDA authorizes the use of polymeric substances in food-contact applications in various sections of the Code of Federal Regulations. As discussed in further detail in one of our earliest StepLadder articles on FDA's Food Additive Regulations, these include, for example, high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and polypropylene (PP) homopolymers and copolymers under 21 C.F.R. 177.1520 ("Olefin polymers"), and polyethylene terephthalate (PET) under 21 C.F.R. 177.1630 ("Polyethylene phthalate polymers"), among many others. While the food additive regulations often describe the list of starting substances used in the manufacture of these polymers, as well as certain end-tests that the finished polymers are required to meet in specific food contact applications, one item is conspicuously absent from these regulations – the catalysts, aids to polymerization, and processing aids used to start, support, modify, and terminate the polymerization process.

The omission of these substances from the food additive regulations is not accidental. In fact, such omission represents a practical realization by FDA that it would be prohibitively challenging to direct agency resources to evaluating and listing every potential combination of substances used to support a polymerization reaction. FDA effectively declared as much in 1968, when the Agency’s Assistant Director for Regulatory Programs, Dr. Lessel Ramsey, acknowledged that catalysts are used "by the dozens, if not by the hundreds. And there are no catalysts listed in the regulations unless the petitioner actually insisted that the catalysts be put there."¹ The result of this longstanding position is that FDA's food additive regulations are largely (but not exclusively) devoid of listings for substances specifically intended to support the polymerization process. Where such substances do appear in the food additive regulations, they are there largely because, as Dr. Ramsey recognized, the petitioner requested that they be included for competitive reasons.

Therefore, under what has become known as the "Basic Resin Doctrine," the use of a catalysts, chain-transfer agents, polymerization inhibitors, and other substances specifically intended to support the polymerization process of an otherwise cleared polymer are not, themselves, required to be listed in a food additive regulation, provided that certain criteria are met:

• The use of the substance is necessary to support the polymerization-reaction of the polymer.
• The substance is used at only to the extent necessary to accomplish the intended technical effect (generally, when used at less than 0.5% by weight of the finished polymer, though higher use levels also may be acceptable, as evaluated on a case-by-case basis by taking into consideration relevant chemistry and toxicology information).
• The substance is expected to become incorporated into the finished polymer or removed during further processing, such that would not be any expectation of significant exposure to the substance (or its degradation products, if applicable).
• The use of the substance does not render the polymer or the finished food-contact material injurious to health.

While the first three criteria are generally satisfied with a simple "yes" or "no" analysis, the fourth represents the most substantive aspect of the basic resin analysis. All food contact materials must be of a "purity suitable for [their] intended use" pursuant to FDA's food manufacturing practice (GMP) regulation, found at 21 C.F.R. § 174.5 ("General provisions applicable to indirect food additives"). It follows, therefore, that the use of a basic resin substance must be safe when that substance, or its impurities/byproducts, are potentially present in the diet at low levels. Of course, the substance also must not impart an off-taste or odor to food held in the polymeric packaging when used as intended.

When Does the "Basic Resin Doctrine" NOT apply?

Substances Authorized by a Food Contact Notification

In contrast with substances cleared under an applicable food additive regulation, where FDA would otherwise be faced with the task of evaluating near-limitless potential combinations of polymerization processes, substances authorized under an FCN must include information regarding the specific substances used to support the polymerization process, as well as an evaluation of the safety of potential exposures to these substances and their impurities/byproducts.

The distinction between substances cleared by a food additive regulation and substances authorized by an FCN is a recognition of the fact that FDA is tasked with evaluating a significant (but comparatively fewer) number of food contact substance notifications in any given year, and has specific resources dedicated to reviewing the safety of entire manufacturing process (including components of the basic resin). Importantly, only a notifier and its customers are permitted to rely on an FCN authorization, because similar listings for finished polymeric food contact materials may be manufactured using very different processes.² Two companies that intend to manufacture the same ultimate packaging material may use entirely different components in the manufacture of the basic resin, raising new or different questions of safety that need to be considered by the notifier and evaluated by FDA in the course of a suitable purity analysis.

Substances Used in Food Contact Applications by way of an Exemption or Exception

Food contact materials and articles – including polymeric substances – that are the subject of an exemption or exception, do not enjoy the same reliance on the "Basic Resin Doctrine" as cleared substances. For example, manufacturers of polymeric food contact materials and articles that determine that a food contact material or article will not migrate to food in significant quantities (e.g., a "No Migration" position), or will be present in the diet at sufficiently low levels, such that it may be considered Generally Recognized as Safe (GRAS) for the intended use, are still required to establish the suitable FDA status of the substances supporting the polymerization process.

Additives

While substances that support the polymerization process of a substance listed in the food additive regulations, such as those described above, may properly be considered covered by the Basic Resin Doctrine, substances that perform a function separate and distinct from the polymerization process must be evaluated through other means. For example, antioxidants, UV stabilizers, pH adjustment agents, and other substances that perform the function of an "additive" (usually by imparting some kind of technical effect in the finished polymer) are not covered by the "Basic Resin Doctrine."

The "Basic Resin Doctrine" promotes a degree of regulatory efficiency by providing flexibility in the manufacture those polymeric substances otherwise authorized under a food additive regulation. However, manufacturers should be cautious to ensure that the "Basic Resin Doctrine" applies in any given situation. Provided that’s the case – carefully consider the GMP and suitable purity analyses that are required to support a safety assessment for the intended use of the catalyst, chain transfer agent, or the like.

¹ Proceedings of National Conference on Indirect Food Additives (February 12, 1968).

² Competitors that intend to manufacture the same ultimate food contact substance are required to provide FDA with a complete copy of their own manufacturing process, which may differ in terms of substances used to support the polymerization reaction.

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About the Steptoe StepLadder Series

Steptoe & Johnson LLP is pleased to publish the Stepladder series of articles for our clients, prospective clients, and interested companies as a way of educating attorneys and non-attorneys alike about legal and regulatory principles related to food packaging in meaningful ways. While there are many sources of information available online, the StepLadder series is intended to be accessible to, and understandable by all, to help support business decisions related to food packaging compliance.

This information is provided for educational purposes only, is not legal advice, and does not establish an attorney-client relationship with Steptoe. Our lawyers made us write that. If you have legal questions, please consult an attorney. Preferably from a team well-versed in food packaging regulation – and definitely from a group of attorneys that have a good sense of humor. Because you are what you eat… unless your food packaging isn’t a ‘food additive,' in which case you’re not food packaging.