Urinary phthalate monoesters and endometriosis in infertile Japanese women

Phthalates may act as an estrogen and are a potential risk factor for estrogen-related diseases such as endometriosis, We assessed the association between phthalate exposure and endometriosis in 166 consecutive women who presented at a university hospital for consultation regarding infertility. The subjects were interviewed and provided a urine specimen prior to a laparoscopic diagnosis of endometriosis. They were then categorized by the severity of endometriosis as controls (stages 0-1) and cases (stages II-IV). Urinary concentrations of the phthalate metabolites monoethyl phthalate. mono-n-butyl phthalate, monobenzyl phthalate, mono (2-ethyl hexyl) phthalate (MEHP), mono (2-ethyl-5-oxohexyl) phthalate, and mono (2-ethyl-5-hydroxyhexyl) phthalate were measured in 57 cases and 80 controls using high-performance liquid chromatography isotope-dilution tandem mass spectrometry. Adjusted odds ratios for endometriosis in relation to dichotomized individual phthalate metabolites (standardized for creatinine) were calculated. No significant association between endometriosis and any urinary creatinine-adjusted phthalate monoester was seen. Adjusted odds ratio (95% confidence interval) for higher dichotomized MEHP by endometriosis was 1.57 (0.74-3.30). No monotonic trend was seen in urinary creatinine-adjusted concentration of phthalate metabolites by endometriosis stage (p = 0.23-0.90). Our results do not support the hypothesis that higher urinary concentrations of phthalate metabolites are associated with the risk of endometriosis in infertile Japanese women. (C) 2009 Elsevier B.V. All rights reserved.