Migration limit

Migration limited by safety and tast/odor considerations... 

For evaluation of potential inhibitors of migration (e.g., cispla-tin Fig. 4), the concentrations used should be < the concentration that inhibits growth by 50% (Gl ) (see Note 14). This is important in order to evaluate the effect of the inhibitor more specifically on migration, limiting any inhibitory effects on cell proliferation. 

Petersen et al. (1997) reported that, compared with a specific migration limit of 3 mg di(2-ethylhexyl) adipate/dm from PVC cling films used in Denmark, 77% of the films used for fatty foodstuffs sampled from importers, wholesalers and retail shops... 

There are two general principles regarding chemical migration, the purity of the foodstuff and the inertness of the material. The first principle, the purity of the foodstuff, is the raison d etre for the control of specific substances on the basis of known or suspected toxicity. Control can take the form of limitations on the quantity of substance permitted to migrate to foods or food simulants. Alternatively, control can be indirectly via a limit on the quantity of the substance permitted to be present in the finished material or article. These are termed migration limits and compositional limits respectively. 

At the time of writing, DEHA has not yet been included in the EU positive list of additives used to make food contact plastics. With an established TDI of 0.3 mg/kg bw/day and using the normal conservative assumptions of 1 kg food consumed daily and a 60 kg bw, this TDI would give a specific migration limit of 18 mg DEHA per kg food or food simulant. It must be recognised that non-compliance with a migration limit of 18 mg/kg based on this convention does not necessarily mean that the TDI could be exceeded. It seems unlikely that DEHA will be listed until the issue of food consumption factors is resolved. 

One laboratory has carried n measurements under repeatability conditions and obtained an average value y which is compared with a given value m0 (e.g. a specific migration limit). Then one obtains the critical difference as ... 

Restrictions applicable to authorised substances, expressed in maximum quantity in the finished product except for the limits for MEG and DEG expressed as specific migration limits (= 30 ppm in foodstuffs)... 

Only for monoethylene glycol (MEG) and diethylene glycol (DEG), which under certain circumstances can be transferred in unacceptably high quantities, have migration limits in food been provided for in Directive 86/388/EEC. The positive list has been amended on two occasions (Directives 86/388/EEC and 92/15/EEC) and the Commission took the opportunity of a third amendment (Directive 93/10/EEC) to codify all the directives adopted. Now the positive list contains 72 compounds and 42 groups of substances, i.e. 114 chemical products. 

In 1984, after some ten years of discussion, Directive 84/500/EEC on ceramic articles was approved it lays down the specific migration limits for lead and cadmium, according to their intended uses, along with the essentials of the method for checking... 

Thble 12-5 Specific migration limits for lead and cadmium. 

For additives, on the other hand, the list is a partial list currently comprising 289 substances fully evaluated by the SCF whose toxicological characteristics do not necessitate the imposition of any restriction on use other than the overall migration limit. 204 additional substances, fully evaluated by the SCF and 185 of which require a restriction on their use according to the SCF, will be added to the list before long. All of the more important information on the evaluation of substances is to be found in the document entitled Synoptic which is to be distributed on the Internet (address http //cpf.jrc.it/webpack/). 

R = restriction recommended by SCF which may be expressed in a specific migration limit or a value expressed in mg/kg p.c. or in some other way. 

It is possible that styrene will never reach the mass balance migration limit specified by Eq. (14-1) in certain foods because of partitioning effects. The systems most likely to have partitioning effects, i.e. when K 1, are those for styrene between aqueous foodstuffs and PS. Migration is usually highest into fats and oils since styrene is readily soluble in both the fats and polymers so that K < 1. 

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