Compliance Testing vs. Migration Testing: A Primer
Once a packaging material is cleared for use with food, testing is generally required to ensure that the material conforms with applicable regulations or notifications.
Both the U.S. Food and Drug Administration's Food Additive Regulations and the European Union's Directives clear many substances on a generic basis—based on chemical identity. Accordingly, they impose specifications to establish "food contact grade" standards for the use of these materials. Because compliance specifications often take the form of extraction limitations, testing is necessary to assure conformity of the substance or package at hand.
It is important to keep in mind that this "compliance testing" can differ significantly from "migration testing," which is done prior to clearance to determine whether a food contact substance migrates to the food itself. It is also vital to realize that the compliance testing systems in place in the European Union and in the United States are not the same.
EU Testing Scheme
In the European Union, compliance testing—again, to determine whether the use of a food contact article, after it is cleared, meets the necessary specifications—involves the use of food simulating solvents and conditions of time and temperature identical to those used during migration testing to evaluate the substance in support of a "technical dossier" used for purposes of adding new substances to the Plastics Directive. The compliance tests require total migration to be determined, and frequently also require a specific determination of component substances.
The necessary parameters for use in performing either migration testing or compliance testing are summarized in Council Directive 82/711/EEC, as amended, laying down the basic rules necessary for testing migration of the constituents of plastic materials and articles intended to come into contact with food (consolidated version is available here).
Council Directive 85/572/EEC, as amended, sets out the list of simulants that may be used for testing migration of constituents of plastic materials and articles intended to come into contact with food (consolidated version is available here).
Testing Required by FDA
The system in place in the United States is substantially different: migration testing and compliance testing are performed in different ways following different parameters.
A compliance test is performed only for a substance that is explicitly cleared in a Food Additive Regulation or in an effective Food Contact Notification to determine if the provisions of the regulation or notification are met; thus, the compliance test requirements in these clearances vary greatly from one regulation or notification to another.
The compliance tests are relatively easily and rapidly performed analyses that are akin to quality control specifications. Generally, they are of short duration (usually 30 minutes or 2 hours, although occasionally as long as 24 or 48 hours), and typically require only gravimetric analysis for total migration. Only rarely are specific determinations needed for specific substances. More often, limitations on permitted use conditions are imposed or maximum permitted use levels are set for specific substances. The test results are used to determine whether the material or article passes the given specification; they are not intended for assessing dietary exposure.
In contrast, under FDA's migration testing scheme, tests are performed to determine whether the new substance under examination (either polymer or polymer additive)—for which an applicable food-contact status has not yet been established—is expected to become a component of food and, thus, would be subject to FDA's jurisdiction as a "food additive." If the substance is found to migrate, the results can be used to ascertain the potential contribution of the substance to the human diet. The conditions of migration testing are intended to simulate the actual intended conditions of use of the finished food contact article in which the substance of interest will be used.
Migration testing is typically performed over a longer period than the compliance testing (usually 10 days, or longer), and virtually always requires analysis of the food simulants for one or more specific potential migrants (rather than the total migration of all substances that may come from the article, which may include materials already cleared). As the testing involves determinations for specific substances, the analyses are almost always far more complex than the simple "total extraction" compliance tests and usually employ sophisticated, computer-controlled instrumentation that requires analytical expertise in chemical analysis.
It is only a coincidence that some testing conditions to determine compliance with a regulation—tests often referred to as "end tests"—have identifying names ("Conditions of Use") similar to the more rigorous testing conditions (also often referred to by the same set of "Conditions of Use") used to acquire data needed to establish that a substance used as a component of a food contact article is not expected to migrate to food, or the data needed to prepare a formal Food Contact Notification. There are, indeed, numerous instances in which the compliance test bears no resemblance to the food-simulating migration testing, even though both refer to the same "Conditions of Use."
In point of fact, the type of testing needed depends on the purpose for which the testing results will be used. If a substance is specifically listed in a Food Additive Regulation or an effective Food Contact Notification, and testing is needed to determine compliance with the regulation or notification (as a specification on the substance or article in which the substance is used as a component), the end test must be satisfied. In such a case, the compliance testing must be performed strictly as set forth in the regulation or notification; tests using FDA's guidance for migration testing, "Guidance for Industry: Preparation of Premarket Notifications for Food Contact Substances: Chemistry Recommendations," will not answer the question of whether the material meets the specification unless a correlation between the specification and the migration test results has been established.
If, on the other hand, a substance is not specifically listed and a determination is needed on whether the substance may reasonably be expected to migrate to food, or such data must be supplied to FDA to bring about an effective Food Contact Notification, migration testing simulating the intended conditions of use is essential. In such a case, the tests need to be performed in accordance with the "Chemistry Recommendations" document noted above; specification testing, as may be found in Title 21 of the Code of Federal Regulations, for example, is irrelevant.
 In the United States, beginning in 2000, many food contact substances began to be cleared on the basis of Food Contact Notifications. While this type of clearance is proprietary, not generic, compliance with any terms of the notification is required and often demands the same type of testing as is required for those substances cleared by regulation.