Assessment of the total effective xenoestrogen burden in extracts of human placentas

Abstract

We have standardized a method to assess the total effective xenoestrogen burden (TEXB) in human placentas by the extraction and separation by high-performance liquid chromatography of two fractions containing lipophilic xenoestrogens (alpha) and endogenous hormones (beta), followed by assessing their estrogenicity in MCF-7 breast cancer cell-based E-Screen and Yeast Estrogen Screen (YES) bioassays. The means of TEXB alpha concentrations (in estradiol equivalent (Eeq) units) were 1.32 and 0.77 Eeq pM g⁻¹ placenta in the E-Screen and YES, respectively; TEXB beta concentrations were 6.97 and 11.56 Eeq pM g⁻¹ placenta, respectively. The interclass correlation coefficient was low and a fair level of agreement was observed after kappa test correction. According to the E-Screen and YES, TEXB alpha was ≥LOD in 70.0 and 55.0% of the placentas and 92.5 and 82.5% in beta, respectively. Although both bioassays can be recommended for assessing TEXB, there is greater experience with the use of the E-Screen for estrogenic assessment after extensive extraction of complex human matrices.

Keywords::

• Total effective xenoestrogen burden
• placenta
• prenatal exposure
• E-Screen
• Yeast Estrogen Screen

Acknowledgements

We are indebted to all participants, without whom this work would not have been possible. The authors are also grateful to the nursing staff of the maternity wards and special care nursery for their cooperation. The authors are grateful to Richard Davies for editorial assistance. This work was supported by grants from the Spanish Ministry of Health (INMA G03/176), the Spanish Ministry of Science and Innovation (Juan de la Cierva Programa-FSE) and the European Union Commission (QLK4-1999-01422, QLRT-2001-00603 and FP7-ENV-2007-1-212502).

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.