Association of phthalate esters with endometriosis in Indian women

Objective To evaluate the possible association between phthalate esters ( PEs) and the occurrence of endometriosis. Design Case - control study. Setting Department of Reproductive Medicine, Bhagawan Mahavir Medical Research Centre, Maternal Health and Reproductive Institute and Department of Analytical R& D, Hetero Research Foundation, Hyderabad, Andhra Pradesh, India. Sample Blood samples were collected from 49 infertile women with endometriosis ( study group); 38 age- matched women without endometriosis ( control group I) but with infertility related to tubal defects, fibroids, polycystic ovaries, idiopathic infertility and pelvic inflammatory diseases diagnosed by laparoscopy and a further group of 21 age- matched women ( control group II) with proven fertility and no evidence of endometriosis and other gynaecological disorders during laparoscopic sterilisation. Methods Concentrations of PEs were measured using gas chromatography. Main outcome measures Evaluation of PEs concentrations in women with endometriosis compared with women free from the disease. Results Women with endometriosis showed significantly higher concentrations of di- n- butyl phthalate ( DnBP), butyl benzyl phthalate ( BBP), di- n- octyl phthalate ( DnOP) and diethyl hexyl phthalate ( DEHP) ( mean 0.44 [ SD 0.41]; 0.66 [ SD 0.61]; 3.32 [ SD 2.17]; 2.44 [ SD 2.17] micrograms/ ml) compared with control group I ( mean 0.08 [ SD 0.14]; 0.12 [ SD 0.20]; 0; 0.50 [ SD 0.80] micrograms/ ml) and control group II ( mean 0.15 [ SD 0.21]; 0.11 [ SD 0.22]; 0; 0.45 [ SD 0.68] micrograms/ ml). The correlation between the concentrations of PEs and different severity of endometriosis was strong and statistically significant at P < 0.05 for all four compounds ( DnBP: r = + 0.73, P < 0.0001; BBP: r = + 0.78, P < 0.0001; DnOP: r = + 0.57, P < 0.0001 and DEHP: r = + 0.44, P < 0.0014). Conclusions This study suggests that PEs may have an aetiological association with endometriosis.