PLASTICIZERS IN PATIENTS WITH END-STAGE R ENAL-FAILURE - ASPECTS OF EXPOSITION AND TOXICITY

Di(2-ethylhexyl)phthalate (DEHP) is the most commonly used plasticizer for polyvinylchloride (PVC). DEHP is added to improve the flexibility of the material. Many medical devices, such as blood lines in hemodia lysis (HD) and bags for CAPD fluids, are made of PVC. Since DEHP is no t chemically bound to the polymer, it leaches out of the plastic matri x. It has been shown that patients on HD and CAPD are exposed to consi derable amounts of DEHP and its main hydrolysis products. We and other s found small amounts of DEHP in CAPD plastic bags prior to use, while concentration of the hydrolitic product mono(2-ethylhexyl)phthalate ( MEHP) was four-to seven-fold higher. Serum concentrations of DEHP and PA in patients on HD or CAPD were significantly higher compared to ind ividuals with normal renal function. During hemodialysis the serum con centrations of DEHP, MEHP and 2-ethylhexanol are rising significantly whereas a pronounced drop in the serum concentrations of phthalic acid could be noticed. The biological consequences of chronic exposure to DEHP and metabolites are unknown. Evidence could be raised that DEHP i s involved in the pathogenesis of peritoneal sclerosis and formation o f renal cyst, whereas neither DEHP nor its metabolites do convey uremi c pruritus. As we could show, there is a clear dose-dependent suppress ive effect on leukocyte function by MEHP and phthalic acid as given by measuring respiratory burst capacity of these cells. This effect coul d even be demonstrated in the presence of a high glucose-mediated osmo larity and a high lactate concentration. Further studies have to eluci date whether these observations are clinically relevant.