Loss of Phthalic Acid Ester from Polyvinyl Chloride Tubing into Various Fluids ¹

Migration of phthalic acid esters (PAE) from polyvinyl chloride (Tygon) tubing, approved for use with processed milk and milk products, was measured under conditions simulating normal daily use. Squares of tubing were soaking in water at 18, 44, and 72 C; milk at 38 C; aqueous solutions of two chlorinated alkaline cleaners at 62 C and use dilution; and three sanitizers at 24 C and use dilution. Each soaking solution was extracted using the AOAC Method for organochlorine pesticides and analyzed quantitatively for PAEs by gas liquid chromatography. Water at 72 C extracted greater amounts of PAEs than water at 18 or 44 C. Milk extracted the least amounts of PAEs; values were usually less than 1 ppb per day. Little difference was seen between the two chlorinated alkaline cleaners. Sanitizers, in general, extracted the greatest quantities of PAEs, averaging about 3 ppb per day. Leaching patterns of the individual sanitizers varied. Deformation tests were made on the used squares of tubing with a penetrometer. No change was found compared to samples of unused tubing (control), indicating longer use and greater PAE loss is necessary before tubing flexibility is affected.