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-ethylhexyl)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

Seven elderly patients on stable CAPD using Fresenius instruments and dialysate and 6 age-matched healthy controls.

INTERVENTIONS

During a routinely performed peritoneal equilibration test (PET), blood and dialysate samples were drawn before and 120 and 240 min after the dwell was started. In addition, blood samples were taken from a group of volunteers participating in a pharmacological study.

MEASUREMENTS

Quantitative analysis of DEHP and its hydrolysis products was performed by selected ion-monitoring gas chromatography/mass spectrometry, operating the mass spectrometer in a combined positive and negative ion chemical ionization mode.

RESULTS

Serum concentrations of DEHP and PA were significantly higher in patients (median: 0.079 microgram/mL, range: 0.032-0.210 microgram/mL; and 0.167 microgram/mL, range: 0.097-0.231 microgram/mL, respectively) than in controls [0.0195 microgram/mL, range: 0.016-0.025 microgram/mL (p = 0.0027) and 0.0120 microgram/mL, range: 0.006-0.034 microgram/mL (p = 0.0026), respectively]. Concentration of MEHP in the fluid of CAPD bags prior to use was four times higher than that of the parent compound. During 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 microgram/mL) to 0.022 microgram/mL (range: 0.005-0.058 microgram/mL) (p = 0.017), and from 0.087 (range: 0.075-0.097 microgram/mL) to 0.05 microgram/mL (range: 0.023-0.064 microgram/mL) (p = 0.017), respectively, while the concentration of DEHP remained stable. Remarkably high concentrations of PA (0.129 microgram/mL; range: 0.038-0.466 microgram/mL) were found in CAPD bags prior to use, and these concentrations tended to increase during dwell time, without statistical significance, however (0.135 microgram/mL; range: 0.073-0.659 microgram/mL, p = 0.062).

CONCLUSIONS

Patients on CAPD are regularly exposed to considerable amounts of phthalic ester derivatives, mainly to MEHP and PA. MEHP seems to be well absorbed by the peritoneal membrane. The long-term effects of this exposure remain to be elucidated.