Potential migration

An important quantity which can be calculated at equilibrium conditions is the amount of substance migrated into the food or food simulant at equilibrium, mF,e. Provided that the migration potential in the polymer, i.e. the initial amount of migrant dissolved in the polymer, mP0, is known then from mass balance calculations the following equation can be derived ... 

Baner, A.L., Franz, R. and Piringer, O., 1994, Alternative methods for the determination and evaluation of migration potential from polymeric food contact materials. Deutsche Lehensmittel-Rundschau, 90(5), 137-143. and 90(6), 181-185. 

BARBER, M., COPE, R. and SIDWELL, J. (2003) Investigation into the application of food contact laminated materials examination of migration potential and recommendations for safe use (Final report). FSA Project No. A03034. 

When applying the conventional food contact ratio the worst-case migration potential did not exceed the SML for any of the substances derived from plastics nor did the calculated worst-case exposure exceed the ADI/TDI or other exposure restriction value in any products. However, when the actual food contact ratio was applied the ADI/TDI or other exposure restriction value of several substances could theoretically be exceeded. The worst-case calculations assume that intimate contact is made with the entire surface of the packaging. This is not the case for the majority of snack foods that are solids or semi-solids and so the actual area of contact made will be less than the total area available for contact (e.g. crisps). The levels of those migrants (diisobutyl phthalate, dicyclohexyl phthalate, dibutyl sebacate, diphenyl 2-ethylhexyl phosphate and 2-ethyl-1-hexanol) that had the potential to exceed the assigned restrictions, assuming 100% migration, were determined in foods. Of the five substances tested for, only one, dicyclohexyl phthalate, was detected in one of the foodstuffs (tortilla corn chips), at a concentration of 0.60 ppm. 

Relatively high levels for the worst-case migration potential for styrene were also calculated (the SML for styrene is currently under review) and the concentration of styrene in the appropriate foodstuffs was determined. Low levels of styrene were measured but in all cases were less than 5 ppb. Thus despite the high contact temperatures between the foodstuff and the packaging, the relatively high packaging area mass of food ratio and the presence of fat on the food surface, the migration levels observed were low. 

Seme R. J., Arthur R. C., and Krapka K. M. (1990) Review of Geochemical Processes and Codes for Assessment of Radionuclide Migration Potential at Commercial FEW Sites. 129pp., US Nuclear Regulatory Commission. 

The pH of the ash leachate is one parameter that controls the migration potential of the elements leached from the ash. Fig. 5 shows the variation in pH that exists between the various leachates collected. Due to the high concentrations of Ca and Mg in most ashes, the majority of leachates are alkaline. Notable exceptions are the slightly acidic leachate of the EKY-FA sample and the acidic leachate of the NEMO-FA and SI-BA samples. These acidic leachates will allow metals leached from the ash to remain in solution, increasing the mobility of these elements. This mobility contributes greatly to the potential for contamination of groundwater aquifers by such solutions. 

For solid products the risk of migration is low and therefore interaction studies are not required over and above the normal stability test results. For semi-solid products it is necessary to look particularly at the migration of additives, vapour permeation and the effects of the product on the physical parameters of the pack. For liquid products the migration potential for the specific formulation is required, and the determination of active ingredient content under simulated use, along with extractives data is required for parenteral and ophthalmic products. Moisture permeation is important, particularly for solid products packaged in blister packs. 

Still Moving Measured Sedimentation (or migration) potential... 

No releases to land or groundwater or to a landfill unless the substance has negligible groundwater migration potential... 

Pt loss or migration Potential cycling Single cell or stack... 

Seme, R.J., R.C. Arthur, and K.M. Kmpka. 1990. Review of geochemical processes and codes for assessment of radionuclide migration potential at commercial LLW sites. PNL-72S5. Pacific Northwest Lab., Richland, WA. 

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