THE FATE OF LEACHED DI(2-ETHYLHEXYL)PHTHALATE IN PATIENTS UNDERGOING CAPD TREATMENT

Objectives: To evaluate the degree of exposure to and the fate of di(2 -ethylhexyl)phthalate (DEHP) and its major derivatives mono(2-ethylhex yl)phthalate (MEHP), 2-ethylhexanol (2-EH), and phthalic acid (PA) in patients undergoing regular continuous ambulatory peritoneal dialysis (CAPD) during a 4-hour dwell period. Design: Prospective, controlled. Setting: Teaching hospital, Department of Nephrology. Participants: Se ven elderly patients on stable CAPD using Fresenius instruments and di alysate and 6 age-matched healthy controls. Interventions: During a ro utinely performed peritoneal equilibration test (PET), blood and dialy sate samples were drawn before and 120 and 240 min after the dwell was started. In addition, blood samples were taken from a group of volunt eers participating in a pharmacological study. Measurements: Quantitat ive analysis of DEHP and its hydrolysis products was performed by sele cted ion-monitoring gas chromatography/mass spectrometry, operating th e mass spectrometer in a combined positive and negative ion chemical i onization mode. Results: Serum concentrations of DEHP and PA were sign ificantly higher in patients (median: 0.079 mu g/mL, range: 0.032 - 0. 210 mu g/mL; and 0.167 mu g/mL, range: 0.097 - 0.231 mu g/mL, respecti vely) than in controls [0.0195 mu g/mL, range: 0.016 - 0.025 mu g/mL ( p = 0.0027) and 0.0120 mu g/mL, range: 0.006 -0.034 mu g/mL(p = 0.0026 ), respectively]. Concentration of MEHP in the fluid of CAPD bags prio r to use was four times higher than that of the parent compound. Durin g the first 4 hours of dwell time, the concentrations of MEHP and 2-EH in dialysate consistently decreased from 0.177 (range: 0.137 - 0.239 mu g/mL) mt) to 0.022 mu g/mL (range: 0.005 - 0.058 mu g/mL) (p = 0.01 7), and from 0.087 (range: 0.075 - 0.097 mu g/mL) to 0.05 mu g/mL (ran ge: 0.023 - 0.064 mu g/mL) (p = 0.017), respectively, while the concen tration of DEHP remained stable. Remarkably high concentrations of PA (0.129 mu g/mL; range: 0.038 - 0.466 mu g/mL) were found in CAPD bags prior to use, and these concentrations tended to increase during dwell time, without statistical significance, however (0.135 mu g/mL; range : 0.073 - 0.659 mu g/mL, p = 0.062). Conclusions: Patients on CAPD are regularly exposed to considerable amounts of phthalic ester derivativ es, mainly to MEHP and PA. MEHP seems to be well absorbed by the perit oneal membrane. The long-term effects of this exposure remain to be el ucidated.