Correlation of specific migration (Cf) of plastics additives with their initial concentration in the polymer (Cp).

The first list of plastics additives which may be assigned restrictions in a future amendment to Directive 90/128/ EEC is likely to contain over 200 substances. If food consumption factors are taken into account many compounds on this list could have restrictions removed but there would, without doubt, still be many additives with restrictions. Extensive migration testing of food contact plastics containing restricted additives to ensure compliance would be required. These limits would be difficult to enforce, add significant cost burdens on the packaging industry and, for these reasons, may not provide improved consumer safeguards. An alternative means of control has been proposed based upon polymer composition. However, in order to support such a scheme a reliable correlation between migration of additives to their composition in the polymer must be demonstrated. There has been strong interest in establishing this relationship and a feasibility project to investigate the specific migration of four commonly used additives has been successfully completed. The study was initially funded for 1 year, by the Ministry of Agriculture, Fisheries and Food (MAFF) and industry. Analytical methods to determine the additives in food simulants have been developed and linear correlations have been demonstrated between the concentration of all four additives and their specific migration levels for each polymer studied. Experimental migration data have been compared with those generated by mathematical models.

Hydrolysis studies on oleamide in simulated gastrointestinal fluids.

Hydrolysis studies using simulated gastrointestinal fluids have been performed on oleamide, an important fatty acid amide slip additive used in plastics food packaging. Experiments have been conducted using the simulated gastrointestinal fluids, specified by the Scientific Committee for Food for hydrolysis studies, and with slightly modified preparations believed to be more representative of the in vivo situation. The degree of hydrolysis in simulated gastric fluids was found to be negligible after incubation for 4 h at 37 degrees C. Addition of 'bile salts' to simulated intestinal fluid was found to significantly increase the degree of hydrolysis to about 95% loss of oleamide after incubation for 4 h at 37 degrees C. Stoichiometric formation of oleic acid, an innocuous substance, was also demonstrated. It has therefore been concluded that ingestion of the very low levels of oleamide expected to migrate into most foods from food packaging is unlikely to pose a threat to the health of the consumer.

Migration studies on fatty acid amide slip additives from plastics into food simulants.

Specific migration studies, using food simulants, have been conducted on a range of polymers which are used in food packaging and contain commonly used fatty acid amide slip additives. Migration levels using the test conditions (10 days at 40 degrees C) were found to depend primarily upon the food simulant and the polymer type, with the fat simulant and low density polyethylene giving the highest values in the range 1.8-3.1 milligrams of fatty acid amide per kilogram of simulant. Extremely low levels of migration, < 0.05 milligrams of fatty acid amide per kilogram of simulant, were found with aqueous food simulants for all plastics tested, and fat simulant with PVC and polystyrene plastics.

Testing polymeric coatings on metal and paper substrates.

The predicted migration test requirements for food and beverage cans with internal lacquer coatings and plastics paperboard composites against future EC legislation, are described. In a project currently in hand at Pira International on behalf of the UK Ministry of Agriculture, Fisheries and Food, some of the problems which arise when migration testing food and beverage cans with the food simulant 3% (w/v) acetic acid solution are being investigated. The 3% (w/v) acetic acid simulant has a tendency to penetrate the lacquer coating resulting in corrosion of the metal substrate. Experiments in hand and planned on this problem, with some of the initial results, are presented. There are also problems with overall migration testing of food packaging consisting of plastics paperboard composites with the fatty food simulant (olive oil). With one particular problem there is at present no obvious answer.

Effects of large sample loads on column lifetime in preparative-scale liquid chromatography.

In preparative-scale liquid chromatography of proteins, the use of high sample concentration and large sample mass may result in irreversible adsorption to the support surface. This can change the stationary phase characteristics, reduce the capacity, shorten the column lifetime and diminish the economic viability of a particular separation method. Column recycling and regeneration can influence the throughput (mass purified per time unit) and selectivity, and affect the reproducibility. The effects of large sample loads on column lifetime and performance were evaluated for three strong anion-exchange columns: (1) a silica support with a quaternized polyethyleneimine (PEI) coating, (2) a polymeric support with an adsorbed PEI coating which also was quaternized, and (3) a polymeric support with a proprietary quaternary amine stationary phase. The column capacity for proteins was measured by frontal chromatography and monitored as a function of cycle number. The column lifetime was determined by examining chromatographic properties subsequent to the frontal chromatography. The change in protein binding capacity was then compared to the change in nitrate binding capacity. The column performance was evaluated under analytical conditions by measuring the change in resolution of standard protein mixtures.

Migration from food contact plastics. Part I. Establishment and aims of the PIRA project.

In the European Community regulatory approaches adopted by individual Member States to the control of food contact plastics differ markedly and, as a result, the European Commission has identified a need for harmonized legislation in this sector. The Commission requested its Scientific Committee for Food to advise on the toxicity of monomers and other starting substances used in the production of such plastics and the Committee's report has recently been published. It is apparent that, although some monomers have been studied in depth, for many little or no information was available to the Committee on either the levels migrating into food or their likely toxic effects. The Committee has requested that such information be provided within 3 years. Following discussions between the UK Ministry of Agriculture, Fisheries and Food, PIRA and companies involved in either the manufacture or use of food contact plastics, a Project has been established at PIRA to develop sensitive analytical procedures for the relevant UK-required monomers and to provide the required migration data. As a second part to this project the methodology for determining overall migration is being examined with a view to resolving existing experimental difficulties. The first analytical methods to be developed in the project are those for the determination or terephthalic acid and isophthalic acid. Residual levels of these monomers in plastics and the quantities migrating into food simulants and food have been shown to be very low.