Chemical migration

J.A. Sidwell, UK Food Standards Agency Project A03019, 2001, Further research on chemical migration from food contact rubber and other elastomers — Final project report. 

The physical transport of dissolved organic compounds through the subsurface occurs by three processes advection, hydrodynamic dispersion, and molecular diffusion. Together, these three cause the spread of dissolved chemicals into the familiar plume distribution. Advection is the most important dissolved chemical migration process active in the subsurface, and reflects the migration of dissolved chemicals... 

Natural toxins including fungal toxins chemical migration from packaging veterinary drug residues. 

Chemical migration from packaging into food... 

The nervous system consists of two main units the central nervous system (CNS), which includes the brain and the spinal cord and the peripheral nervous system (PNS), which includes the body s system of nerves that control the muscles (motor function), the senses (the sensory nerves), and which are involved in other critical control functions. The individual units of the nervous system are the nerve cells, called neurons. Nenrons are a nniqne type of cell becanse they have the capacity to transmit electrical messages aronnd the body. Messages pass from one nenron to the next in a strnctnre called a synapse. Electric impnlses moving along a branch of the nenron called the axon reach the synapse (a space between nenrons) and canse the release of certain chemicals called neurotransmitters, one of which, acetylcholine, we described earlier in the chapter. These chemicals migrate to a nnit of the next nenron called the dendrites, where their presence canses the bnild-np of an electrical impnlse in the second nenron. 

It is important to note two things in this analysis first, the reactions which govern silicate phase equilibria occur in a system closed to large-scale chemical migration. This corresponds to a pore-water sediment system of local equilibrium. Second, the most striking mineralogical change—the crystallization of feldspar—is, in fact, the result of the instability of another phase, montmorillonite. The use of... 

Early work on phthalate esters (section 1.2) and several monomers such as styrene, which are used to make plastics, demonstrated that chemical migration can occur from packaging into food. There has been a huge amount of practical work on this over the last thirty years (Gilbert, 1997), much of it on plastics. Thus there are now in place detailed controls on this aspect of plastics in the European Union (EU) and the USA. The controls in the EU have been fully implemented in Great Britain (FCM Unit, 2000). 

Research on chemical migration from other types or components of packaging material - e.g. glass, wood, cork, coatings, adhesives - has been carried out sporadically. There is now a concerted UK programme to study chemical migration from these so that problems can be identified and dealt with in a consistent way (Working Party on Chemical Contaminants from Food Contact Materials and Articles, 1999). 

Any chemical migration into food is important because it can have two impacts on the food ... 

All parties involved in the production, transport, selling and consumption of foods need to be aware of the potential for chemical migration. Each needs to ensure that packaging materials are correctly specified for the intended application so that there is no excessive chemical migration. The chain of care... 

Chemical migration and the main factors that control it... 

These effects notwithstanding, even if the packaging does not suffer from such an obvious strong interaction with the food, the nature of the food still has a pronounced influence on chemical migration because it determines the solubility of any packaging chemical in the food and so influences the amount of migration that may occur. Foods can be conveniently classified into five... 

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. 

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