Additive migration plasticiser

Health and safety concerns over PVC are mostly due to the possible leaching out of the residual monomer in addition to certain additives and plasticisers used. In this context, there has been a growing concern over PVC toys (pacifiers and teething rings in particular), that these additives can be released into a child s mouth when the toy is chewed. Old vinyl intravenous (IV) bags, as used in hospitals, have also been shown to leach some DEHP plasticiser. It has been shown that there is also a possibility of the residual monomer and other additives migrating into drinking-water from PVC bottles [13], or from PVC water pipes [14, 15]. 

In addition to plasticisers, there are a number of different additives used for different purposes, i.e., stabilisers used in PVC window profiles and pipes are mostly lead-based, or they can be either barium/cadmium/or zinc compounds. All of these can pose a health hazard if they migrate out of the system above certain concentrations. 

Further studies of the effect of in vitro hydrolysis by digestive fluid simulents on the hydrolysis of polymer additives migrating into food were conducted by Fiamdani and co-workers [1]. These workers assessed the safety of polymeric plasticisers capable of migrating into food by an in vitro study of the hydrolysis of poly( 1,2-propylene adipate) by such fluids. 

L. Fantoni and C. Simoneau, European survey of contamination of homogenised baby food by epoxidised soyabean oil migration from plasticised PVC gaskets, Food Addit. Contain., 20(11) (2003) 1087-1096. 

Three case studies have been selected in order to draw out some of the principles and considerations described above. They are (i) the migration of a residual monomer from a can coating (ii) the migration of an additive from a plasticised plastic film (iii) the migration of a photoinitiator used in a printing ink. 

The name of the resin material, the name and address of the manufacturer, the chemical name, the complete formulation, characteristics and quantity of all ingredients and the function are required where the material is to be used in a container which will be exposed very intimately to the product, such as a large volume parenteral solution or eye drop. The identity, using IR absorption along with a reference spectrum must be provided. Additives, particularly those likely to migrate, including antioxidants, plasticisers, catalysts, initiators and materials such as phthalates, adipates and organic tin in PVC or any dyes used in the resin must also be identified. 

On the other hand, there are also studies showing the effects of UV irradiation on the change of migration characteristics of the matrix polymer, (i.e., effect on the migration of phthalate ester plasticisers from clear PET water bottles [87]), and some data are provided on the effects of ionising irradiation on polymer additives, monomers and polymers themselves in general [88]. 

Large amounts of plastic are produced and used in various spheres of human activity, which are ultimately discarded as pollutants containing residues such as plasticisers, solvents and harmful products which can migrate out of the materials. Therefore, the toxicological properties of plastics can be characterised as migratory or derivatives formed under the influence of the environment. Plastics contain many additives which alter its properties and it is important to know the level of these constituents to regulate by maximum concentrations allowable in the plastic [2-6]. 

But plastics contain low molecular compounds such as oligomers and sometimes monomers, and additives such as plasticisers, lubricants, stabilisers and antioxidants, which are absolutely necessary either for the processing or the stability of the final polymeric materials. The drawback of using these is the potential migration of these additives from the package into the packed material. This is a problem of major interest where food or drugs are concerned. 

The most common causes of ageing processes that films exhibit are (1) migration of additives from the matrix (common in the case of plasticisers, this leads to stiffer and less extendable materials, decreasing the protection function of the packaging) (2) chemical ageing (through oxidation). 

---