Determination of Migration Rates for Certain Phthalates

Survey of chemical substances in consumer products No. 149, 2016

The purpose of the report is to suggest migration rates for the phthalates DEHP, DINP, BBP, DBP and DIBP in soft PVC. The suggested migration rates will be based on numerous migration studies from the accessible literature. The background to varying migration rates reported in the literature will be investigated, discussed and evaluated.

One of the major factors on the migration rate is the way the migration analysis is carried out. Therefore, very different results were obtained depending on how vigorous the applied dynamic forces were. Due to that major factor, it has been necessary to divide the proposed migration rates according to the experimental set-up used. The analytical methods to determine the migration of phthalates are therefore divided into three categories: mild, medium and harsh conditions. The mild conditions result generally in lower migration rates compared with the in vivo adult migration rates for the simulation of children’s sucking and chewing on soft PVC products. The head over heels method (HOH) is judged as the most documented method of all, mostly for the migration rates for DINP to artificial saliva, but also a few for DEHP. The HOH method seems to be the most realistic method, since the given product is rotated once per second, which resembles how a child will chew on a toy. For this reason and because the other methods are very different in their approach, the HOH method is recommended as the reference method for the determination of migration rates for phthalates well knowing that realistic migration rates are difficult to determine in vitro or adult in vivo studies. Calculations have been made in order to estimate migration rates for the five phthalates. The basis is the HOH method, since this method seems to give the most realistic migration rates. The estimated migration rates are quite close to each other (between 10 and 13 µg/cm2/h). The migration rates for DIBP and DBP should in theory be higher than the migration rates for DINP and DEHP if the content of the phthalates in the products are similar. The reason for the similar migration rates estimated is that the concentrations of DIBP and DBP in most cases are lower than the concentration of DEHP and DINP in the products. Even though results indicate that there is no correlation between the content and migration, very low contents of phthalates are expected to give relatively lower migration rates.

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