PPXX: Modelling the Migration From PVC-U Pipes Into Drinking Water

Abstract

In the framework of the German Environmental Agency (UBA) requirements of plastic articles in contact with drinking water, the compliance is verified by comparing migration levels, CW’s, of substances contained by the plastics with specific limits in drinking water (so-called MTCtap’s). In practice, the analytical determination of the CW’s is often a challenging, time and costs intensive task. This is especially true for materials like PVC-U where the migration levels are, in most cases, far below the detection limits of the most modern analytical methods.

For such situations, an UBA Guideline recommends the use of migration modelling for the estimations of CW’s. To perform such calculations a series of input parameters are needed, among them the diffusion and partition coefficients, DP’s and KPW’s, of the migrating substances are the most challenging ones. In recent years by investigating migration of substances from a series of polyolefines into water, has developed methods which allow the estimation of “conservative” D+P’s and K+PW’s, for compliance migration calculations for any organic additive found in these polymers.

In this presentation, the extension of these results for a series of substances migrating from PVC-U samples in drinking water will be presented. It will also be shown how this information was implemented in a special software with which migration estimations as stipulated in the KTW-guideline can be performed.