What End Test Requirements Apply to Polymer Blends?
When an end test is required for mixture of polymer with different specification in a food-contact article (i.e., 21 CFR 177.1520 + FCN 178)? Are the extractives limitations of different polymers applicable to the finished article?
How end-test requirements or extractives limitations are applied in practice to a mixture of two separately cleared substances depends on the nature of the underlying regulatory clearances for those substances. The U.S. Food and Drug Administration's so-called mixture doctrine permits a manufacturer to physically blend two different polymers or other combinations of substances if all are cleared by FDA for their intended use, or are exempt in some way (GRAS, prior sanctioned, a non-migrant, or deemed exempt under the Threshold of Regulation rules). If the clearances for the components of the mixture are provided in a regulation (i.e., 21 CFR 177.1520) or in an FCN (i.e., FCN 178), the relevant listings will specify whether the end-test requirements or extractives limitations, if any, apply to the individual components or to the finished food-contact article.
For example, the end tests in 21 CFR 177.1520, paragraph (c), are to be undertaken for the "basic" resin (i.e., on the polymer, itself, not on the finished food-contact article). On the other hand, FCN 178 for polylactide polymers does not specify any end test requirements or extractives limitations on either the polymer or finished food-contact article.
Thus, in this example, the end-tests set out in Section 177.1520 would be undertaken on the polyolefin resin prior to being blended with polylactide. No end test needs to be conducted on the blend.
For more information, see the PackagingLaw.com articles, Compliance Testing vs. Migration Testing: A Primer and Fathoming Food Packaging Regulation Revisited (Section G).