Estimation of plasma levels of bisphenol-A & phthalates in fertile & infertile women by gas chromatography-mass spectrometry

Background & objectives: Bisphenol-A (BPA) and phthalates are utilized widely in consumer products. Due to their ubiquitous presence in the environment, a concern is expressed worldwide about their possible effect on human reproductive health. This study was conducted to compare the internal exposure of BPA and phthalates (using their metabolites as biomarkers) in plasma samples of infertile and fertile women. Methods: A sensitive gas chromatographic-mass spectrometric (GC-MS) method was developed to simultaneously quantify BPA and four phthalate monoester metabolites [namely mono-methyl phthalate (MMP), mono-benzyl phthalate (MBzP), mono-2-ethylhexyl phthalate (MEHP) and mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP)] in human plasma. The method was validated using charcoal-stripped human plasma. Activated charcoal was also utilized to reduce contamination from reagents. The method was designed to account for and/or eliminate background contamination from all sources. Results: The limit of quantification for the method was 5 ng/ml for MMP and MBzP, while 1 ng/ml for BPA, MEHP and MEHHP, respectively. The precision and accuracy were well within the acceptable range. BPA was detectable in 77 per cent of plasma samples of infertile women and 29 per cent of fertile women. All the four phthalate metabolites were detected in plasma samples of both fertile and infertile women. Interpretation & conclusions: A GC-MS was developed and validated to estimate the BPA and four phthalate monoester metabolites in human plasma. It was utilised to analyse the plasma samples from fertile and infertile women. The infertile women showed significantly higher plasma concentrations of MBzP, BPA and MEHHP as compared to fertile women. The levels of MMP and MEHP were not significantly different between the two groups. Further studies need to be done to confirm these preliminary findings