Migrants Specific migrant

Risks associated with plastic packages may be increased by human behavior and lifestyle. It is common to get into the habit of eating only some kind of foods, but this may increase the risk of continuous exposure to a specific migrant from the packaging used for these favored foodstuffs. Frequent consumption of fast foods or microwave meals packaged in plastic films may also exert negative effects in the long term. 

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 the following, a practical guide for a step-by-step procedure is presented to establish a validated method of analysis both for determination of a specific migrant in a food simulant and the residual concentration in a plastic. This procedure was first developed and then applied in a European project (Franz and Rijk 1997) and found to be very practical. It should be considered as a recommendation based on the great practical experience of the analysts involved. 

Analysis of a specific migrant in a food simulant (SML-methods)... 

One of the most important issues regarding safety of food contact materials is exposure of consumers to specific migrants in combination with the toxicity of the migrants. Current EU legislation on food contact materials is primarily... 

Additional information on the chemical constituents of the packaging material, i.e., type and amount of monomer and additives and their migration characteristics, would give the opportunity to calculate the actual exposure to specific migrants. Note that this information is also essential for the interpretation of the analytical results obtained in the screening of migrants. The more information is known prior to analysis, the better the chance that compounds can be identified. 

For the NIAS, there is a more urgent need due to Article 3 of the Framework Regulation (EC 1935/2004) and new upcoming legislation and the same approach to exposure should be used. The only drawback to the NIAS is the fact that these substances are often unknown and thus the toxicity of these substances cannot be used, and therefore it is almost impossible to apply the acceptable or tolerable intake of these NIAS. The combination of actual exposure and toxicology will help to determine the acceptable level of a specific migrant in the migration extract. 

Senthilkumar, K., Watanabe, M., Kannan, K., Subramanian, A.N., Tanabe, S., 1999a. Isomer-specific patterns and toxic assessment of polychlorinated bipenyls in resident, wintering migrant birds and bat collected from South India. Toxicol. Environ. Chem. 71, 221-239. 

In this respect one solution for the estimation of a Dp-value is to correlate the diffusion coefficient with the relative molecular mass, Mr, of the migrant and with matrix specific parameters at a given temperature T in Kelvin. This approach has already been successfully used (Piringer 1993,1994 Limm and Hollifield 1996). The estimation of the diffusion coefficient can be achieved for example using the following heuristic correlation (Piringer 1994 Baner et al. 1996) ... 

The parameter AP accounts for a specific contribution of the plastic material to the diffusion process. Phenomenologically speaking AP has the role of a conductance of the polymer matrix towards the diffusion of the migrant (Chapter 6). Higher values of AP in such polymers as PE lead to increased DP-values while in stiff chain polymers such as polyesters and polystyrenes lower AP-values account for smaller diffusion coefficients for the same migrant. The parameters b and c account for the specific contributions of the migrant and the diffusion activation energy respectively. 

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