Comparative study of the leachability of di(2-ethylhexyl) phthalate and tri(2-ethylhexyl) trimellitate from haemodialysis tubing.

The leachability of both Di(2-ethylhexyl) phthalate (DEHP) and Tri(2-ethylhexyl) trimellitate (TEHTM) or Trioctyl trimellitate (TOTM) from haemodialysis tubing was investigated in 20 patients with chronic renal failure undergoing maintenance haemodialysis. The blood tubing made of common polyvinyl chloride (PVC) plasticized with DEHP (group 1 patients) were replaced with tubing plasticized with TOTM-DEHP (group 2 patients). The patient blood obtained from the inlet and the outlet of the dialyzer was analyzed during a 4 h-dialysis session. Thus, the circulating concentrations of both DEHP and TOTM resulting from the release from dialyzer tubes were estimated using High-performance Liquid chromatograph (HPLC). With the common PVC-DEHP blood tubing, a DEHP quantity of 122.95+/-33.94 mg was extracted from tubing during a single dialysis session (ranging from 55 to 166.21 mg). During the same period, the total amounts of DEHP retained by the patients were 27.30+/-9.22 mg (ranging from 12.50 to 42.72 mg). As for blood tubing plasticized with TOTM-DEHP, 41.80+/-4.47 mg of DEHP and 75.11+/-25.72 mg of TOTM were extracted. During the same period, the amounts of DEHP and TOTM retained by the patients were 3.42+/-1.37 mg and 4.87+/-2.60 mg, respectively. The extraction rate both plasticizers was correlated with serum lipid content (cholesterol+triglyceride) (r(2)=0.75 for DEHP and r(2)=0.64 for TOTM). In the present investigation, less TOTM and DEHP were apparently released from haemodialysis tubing plasticized with TOTM-DEHP than DEHP released from haemodialysis tubing plasticized with DEHP only. TOTM seems to be a superior alternative to DEHP for use in medical devices because of its potential lower leachability. To recommend it as an alternative plasticizer, its possible toxicity towards human body should be investigated before it can be used routinely. However, patients undergoing haemodialysis using tubing plasticized with DEHP only are regularly exposed to non negligible amounts of DEHP. In view of several biological effects previously reported, it is time to reconsider the use of DEHP only as a plasticizer.