Migration of contaminants from milk tubes and teat liners

The survey tested migration of contaminants from various flexible tubes and teat liners used in milk production. A total of 19 samples were analyzed through sensory evaluation and in migration tests with different simulant liquids. Plasticizers were dissolved in diethyl ether or tetrahydrofuran and analyzed in high performance liquid chromatography (HPLC). The most widely used polyvinyl chloride (PVC) tubes contained 37–40% di-2-ethylhexyl phthalate (DEHP) as plasticizer. In some tubes DEHP was to a great extent replaced by a polymeric plasticizer. DEHP was analyzed with reverse phase HPLC directly from milk in a procedure in which a piece of tube was soaked in milk for 1, 3 and 6 d. Tubes containing polymeric plasticizer lost less DEHP into milk, but relatively more than the tubes plastieized only by DEHP. The evaporation residue for migration tests to water was significantly greater for polyadipate tubes compared with tubes plastieized only by DEHP. The evaporation residue from the water extract of the tubes plastieized by polymeric plasticizer was by mass-speetral analysis found to consist of various hydrolyzation products of polyester from 1,3-butandiol and adipic acid. The results obtained are discussed in the light of toxieologieal problems connected with plasticizers.