Specific migration testing

Applications Radiotracer measurements, which combine high sensitivity and specificity with poor spatial resolution, have been used for migration testing. For example, studies have been made on HDPE, PP and HIPS to determine effects of manufacturing conditions on migration of AOs from plastic products into a test fat [443]. Labelled antioxidant was determined radio-analytically after 10 days at 40 °C. Acosta and Sas-tre [444] have used radioactive tracer methods for the determination of styrene ethyl acrylate in a styrene ethyl acrylate copolymer. 

The whole area of specific migration determinations can be subdivided in two phases (i) the pre-analytical migration exposure phase, which is more or less identical to that necessary for overall migration determination and (ii) the pure analytical phase, where the specific migrant must be determined in the respective food or simulant as precisely and reproducibly as possible. This pure analytical migration test phase comprises many considerations to be made and includes so many technical possibilities that it deserves to be described in an own comprehensive section (see Section 10.2). 

In 1982 the first directive in the sector, Council Directive 82/711/EEC, laying down a precise reference framework for the system of checking specific and/or overall migration, was adopted. It establishes what simulating liquids (i.e. liquids which can simulate the extractive capacity of foodstuffs), contact times and temperatures are to be used in migration tests performed under standardized conditions. This reference framework, which may seem unduly rigid given the innumerable conditions of contact in reality, was made flexible by the inclusion of a clause which permits Member States to depart from the standard conditions where these prove to be inadequate in the case in question either for technical reasons or because they are too different from the real conditions. 

The completion of harmonisation of rules for plastic food contact materials and articles is within sight. The finalisation of the positive list for authorised additives is likely to happen in 2008. In 2007 the Commission will, besides the Community list of authorised additives, publish a list of additives authorised at national level for which a valid application for EU authorisation has been made to EES A. Only these substances may be used until evaluation is finalised by EES A and a decision on authorisahon is taken by the European Commission. Another project in the plastics sector is the extension of the rules to multimaterial multilayer structures where the plastic layer is in contact with the food. At this moment only plastic materials which consist entirely of plastic are covered by the plastics Directive. These materials, when they are made up from layers of plastic, constitute only about 15% of the mutilayer market. Other multilayer materials such as beverage cartons, which consist of a food contact layer of plastic and aluminium and/or paper, are not yet covered by specific legislation. Extension of the plastics mles to these materials will have to take into consideration requirements for the non-plastic layers and establish mles for migration testing of these materials. 

Consumption factor (CF) Generally, CFs are used to correct migration test results (measured concentration in food simulant) into an exposure value (average uptake by the consumer with the diet). Specifically, the US... 

Category 111 comprises mbber products for which the R-total is smaller than 0.001 and for which migration testing is not required, except for mbber products containing nitrosamines, nitrosatable substances or aromatic amines and Category 111 substances with a specific migration limit (SML) in Technical document No. 1. 

Specific migration tests shall be carried out using the food simulants and the test conditions specified in the... 

A variety of organic and inorganic colorants are allowed by FDA for indirect food contact other colorants are exempted from FDA regulation based on migration testing in a specific polymer for a specific application (Table 13.1). However, dyes are not allowed by FDA. 

Ion migration of concrete can be tested as a measure of its resistance to chloride penetration using migration tests, of which various versions exist. Some of these tests measure non-steady-state migration, expressed as the depth of penetration of chloride ions into a specimen in an electrical field [34, 35]. Other methods apply an electrical field across a specimen until steady-state flow of chloride ions is detected in the downstream cell [36]. Because of their specific nature, a detailed description of these methods will be omitted. 

---