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- Practical Guide -
Page 81 of 153
corresponding SML value. Therefore, a migration test is necessary. The calculated
specific migration value for Irgafos 168 is significantly smaller as the SML value. A
migration test is not necessary in this case.
5
Experimental verification of migration modelling
Since the migration model decribed in this report has not been fully validated for each and
every polymer type or polymer modification or food packaging application, it is essential to
provide a possibility for experimental verification of modelled migration results. This
requirement is also addressed by Article 5 of the 6
th
amendment of Directive 2002/72/EC
which says that
`...that a relationship between the quantity of a substance in the finished
material or article and the value of the specific migration of the substance has been
established either by an adequate experimentation...'
.
In Annex B of this report a guidance document is given which describes an experimental
procedure which allows industry and enforcement laboratories to confirm compliance with
an SML through the verification of compliance with the corresponding maximum initial
quantity in the plastic. More specifically, this method describes how to measure and derive
experimentally/theoretically the basic diffusivity behaviour (A
P
value) of a given test plastics
material using one or more selected test migrants only. Based on the determined A
P
value,
Q/SM or MIC/SML relationships can be calculated for any other migrant in dependency of
its molecular weight and for the applicable temperature range.
This method is not only applicable for verification purposes but should also be applied in
case of doubt when for instance the polymer specific A'
P
value is not known or applicable
from the tables given in paragraph 3.