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Suitable Purity for the Intended Use: Pet Food Packaging Versus Human Food Packaging

September 2, 2003

By Keller and Heckman LLP’s Packaging Practice Group

The Food and Drug Administration's (FDA) so-called "good manufacturing practices" regulation for food-contact materials, set forth at 21 C.F.R. § 174.5 ("General provisions applicable to indirect food additives"), requires that food-contact materials must be "of a purity suitable for [their] intended use." This requirement applies equally to packaging materials for pet food and packaging materials for human food; however, due to differences between humans and pets, a "suitable purity" determination for one may not be sufficient for the other.

Sensitivity to odors is a factor that can highlight the difference between determining that a packaging material is of a suitable purity for human food packaging and determining that the same material is of a suitable purity for use in pet food packaging. Section 174.5 states that a food-contact product may not impart a taste or odor to the food such that it would render the food unfit for consumption. Some household pets, dogs in particular, have acute senses of smell. Therefore, manufacturers of pet food packaging must be careful to ensure that their packaging materials do not impart an unintended odor or taste to the pet food, which might not be detected by humans, but that would be offensive to the pet.

The mandate of "suitable purity," of course, also relates to safety. A substance may comply with a specific food additive regulation, but still be unsuitable for a particular use if it contains an impurity or additive that would be unsafe when used as intended. In this regard, manufacturers must be aware that the toxicity of certain substances varies from species to species. Therefore, a substance that is non-toxic to humans may raise toxicity concerns when ingested by pets.

Furthermore, when evaluating the safety of a substance for use in contact with food, the potential level of dietary exposure to the substance is considered. For humans, the estimated dietary intake of a substance used in food packaging materials can be diluted by the fact that the human diet consists of many different foods, packaged in an assortment of different materials. Pets, on the other hand, typically consume a diet consisting of a more limited variety of foods packaged in a limited number of materials. Thus, the potential dietary exposure to a given packaging material can be much higher for a pet than for a human. Consequently, a safety evaluation for one species is not necessarily directly applicable to another species.

All food packaging materials, whether for human or for pet food packaging, must be of a suitable purity for the intended use. It is the "intended use," however, that provides the distinction. That is, in establishing the suitable purity of a packaging material for its intended use, it is important to consider whether the end user is a human or a pet.