Meaning
Regulatory provision established by the Food and Drug Administration defines the criteria under which a substance used in a food-contact article is exempted from the requirement of a food additive petition. Compliance with 21 cfr 170 39 relies on the substance having a dietary concentration below 0.5 parts per billion. This threshold allows polymer manufacturers to use specific processing aids or additives without undergoing the full premarket notification process provided the migration levels remain negligible.
Exemption Threshold
Migration limits are the primary mechanism for determining if a chemical falls under the scope of this regulation. When a moulder introduces a new additive into a resin formulation, the potential for that chemical to leach into food must be calculated through validated diffusion models or direct extraction tests. Documentation must demonstrate that the substance is not a known carcinogen and does not possess a chemical structure suggesting potent toxicity.
The process involves identifying every potential migrant from the polymer matrix including catalysts, antioxidants, and thermal breakdown products that might reach the consumer. Rigorous testing using food simulants at various temperatures ensures that the cumulative dietary exposure remains within the safe limit.
Documentation Requirement
Manufacturers must maintain records of the calculated dietary exposure to justify the use of the regulation. A technical dossier for 21 cfr 170 39 typically includes the chemical identity, the intended technical effect in the polymer, and the maximum concentration expected in the final part. These records ensure that the safety of the food contact material is maintained throughout the supply chain from resin producer to the final packer.
Application Boundary
The rule does not apply to substances that are already regulated as food additives or those that are specifically prohibited. If the migration of a substance exceeds the 0.5 parts per billion limit, the user must seek a food contact notification.
