The risk of endometriosis and exposure to dioxins and polychlorinated biphenyls: a case-control study of infertile women

BACKGROUND: A case-control study was designed to determine the possible ass ociation between chronic exposure to dioxins and polychlorinated biphenyls (PCBs), and the occurrence of endometriosis. The study group consisted of 4 2 infertile endometriosis cases and 27 mechanical infertile controls, both groups attending one of the collaborating Centres for Reproductive Medicine , enrolled between 1996-1998. METHODS: Exposure assessment to dioxin-like c ompounds was determined through CALUX (chemical-activated luciferase gene e xpression)-bioassay to measure dioxin-like total toxic equivalents (dioxins and co-planar PCBs), whereas non-co-planar PCBs were determined through ch emical analysis. RESULTS: No association was found between median dioxin-li ke total toxic equivalents (TEQ) and the occurrence of endometriosis in inf ertile women [cases (n = 34): 29; controls (n = 27): 24; NS]. When patients were subdivided based on an arbitrary cut-off value of 100 pg TEQ/g serum lipids, no statistically significant association between very high exposure to dioxin-like compounds and endometriosis was found [crude odds ratio (OR ) = 4.33; confidence interval (CI) 0.49-38.19; NS]. After adjusting for bod y mass index, and alcohol consumption, the risk increased slightly to OR = 4.6 (CI 0.48-43.62; NS). There was no confounding by age, ovulatory dysfunc tion, caffeine intake, smoking or exposure to non-co-planar PCBs. CONCLUSIO NS: The study results showed no statistically significant association betwe en exposure to dioxin-like compounds and the occurrence of endometriosis in infertile women.