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How is Carbon Black Regulated When Used in Packaging for Animal Feed?

October 20, 2010
Question 

Our company manufactures polyethylene sheets and bags that contact animal silage and grain that can be used as human and animal feed. One of the raw materials used is carbon black. Does this raw material have to comply with 21CFR 178.3297 or is this application similar to grocery bags in that the substance "is not reasonably expected to become a component of food under the intended conditions of use" and therefore "it is not a food additive by definition, and may be used without any prior action by, or consultation with, FDA"?

Answer 

Under the regulatory framework for food contact materials, companies are permitted to make independent determinations as to the compliance status of their products. Only materials properly defined as "food additives" are subject to the Food and Drug Administration's (FDA's) premarket clearance requirements. FDA's food additive regulations apply to pet food and livestock feed, as well as to human food. It is possible to reach a conclusion that carbon black does not meet the definition of a food additive under the Act based on a determination that the colorant (and its constituents) are not reasonably expected to become components of food. In that regard, the carbon black, per se, is likely not going to migrate from packaging as it is almost completely insoluble in food and food simulating solvents. That said, carbon black is known to contain polynuclear aromatic hydrocarbons (PAHs) impurities on the surface of the pigment, and some PAHs are known carcinogens.

FDA regulates carbon black, and correspondingly the levels of PAHs in carbon black, under Title 21 of the Code of Federal Regulations (C.F.R.) Section 178.3297 of the food additive regulations; this regulation contains two clearances for carbon black that potentially apply to its use in food contact materials, such as your polyethylene bags and sheets. The first clearance for carbon black is under the listing for "High-purity furnace black (CAS Reg. No. 1333-86-4)." The listing for high-purity furnace black further identifies the cleared color as one that contains total PAHs not to exceed 0.5 part per million and the total level of benzo[a]pyrene, the most potent of all PAHs, not to exceed 5.0 parts per billion "as determined by a method entitled ‘Determination of PAH Content of Carbon Black,' dated July 8, 1994, as developed by the Cabot Corp., which is incorporated by reference in accordance with 5 U.S.C. 552(a) and 1 C.F.R. part 51."

 

The second clearance for carbon black in Section 178.3297 permits the use of the colorant manufactured by the channel process in all polymers intended for contact with food. There are no limitations on the use of the colorant associated with this listing, nor are any specifications set forth in the regulation to describe a suitable grade of carbon black made by the channel process. The regulation requires only that the colorant be manufactured by the channel process, i.e., prepared by the impingement process from stripped natural gas. Historically, carbon black manufactured by the channel process has been understood to be relatively free of harmful impurities compared with the potential level of impurities, such as PAHs, that might be introduced when the black is manufactured by alternative processes, particularly by the furnace process.

 

Despite the absence of any specifications or other limitations applicable to the clearance for carbon black manufactured by the channel process, the good manufacturing practices (GMP) requirements applicable to food contact materials and set forth in Section 174.5 of the regulations state that all packaging materials must be "of a purity suitable for [their] intended use." This "suitable purity" requirement means that any unavoidable residues or impurities that may migrate to food must be present at such low levels as to not render the food adulterated (i.e., harmful to human health or having an off taste or odor). Accordingly, a substance can be found to comply with a relevant food additive regulation, but still be unsuitable for food contact use if, for example, it contains an unsafe level of impurities or causes the food to have a foul taste or odor. Thus, even if the carbon black used in your polyethylene is manufactured by the channel process and thereby cleared under the listing in Section 178.3297, the colorant still must be considered suitably pure with respect to the presence of PAH impurities to be considered compliant with FDA's food additive regulations. Please consult legal counsel to determine your specific legal obligations.