Comparison of Elisa- and LC-MS-Based Methodologies for the Exposure Assessment of Bisphenol A.

Several types of methods, mainly liquid chromatography (LC), have been used for the analysis and assessment of bisphenol A (BPA) in human biological samples. Enzyme-linked immunosorbent assay (ELISA) is also being used for BPA measurement. In this study, we verified whether ELISA is suitable for measuring human samples, namely, serum and urine, by comparing the ELISA results with those obtained by liquid chromatography with multichannel colometric electrochemical detection (LC/ECD) and liquid chromatography coupled to a mass spectrometer (LC/MS/MS). Results of the measurement with LC/ECD showed urinary BPA concentrations to be 1.92 [1.45] +/- 1.99 (mean [median] +/- standard deviation) ng BPA/mL without the correction of urine volume and 1.20 [0.90] +/- 1.10 mug BPA/g creatinine; however, in serum, free and total BPA were not detected. In both samples, a good correlation of the values with the methods was not found. ELISA is one of the powerful measurement methods, since it is convenient and useful for screening bulk quantities. At this point, however, ELISA is not suitable for BPA measurement in human samples because of low levels of BPA in human samples, matrix effect, and specificity of anti-BPA antibody.

Fetal exposure to phytoestrogens--the difference in phytoestrogen status between mother and fetus.

The goal of this study was to investigate fetal exposure to phytoestrogens, estrogenic compounds derived from plants, by measuring serum concentrations of phytoestrogens in maternal and cord blood. This study included 51 mothers scheduled for cesarean section (C-section), to obtain the serum of mother and fetus at almost the same time. Serum concentrations of phytoestrogens, including genistein (Gen), daidzein (Dai), coumestrol (Cou), equol (Equ; a metabolite of Dai), and sulfate-conjugated Gen, were measured in maternal and cord blood samples by LC-MS/MS and HPLC. It was found that phytoestrogens were transferred from mother to fetus. The detection rates of Gen, Dai, Equ, and Cou in cord serum were 100%, 80%, 35%, and 0%, respectively. Levels of Gen and Dai were higher in cord than in maternal serum (mean=19.4 ng/ml vs.7.2 ng/ml and 4.3 ng/ml vs.1.8 ng/ml for Gen and Dai, respectively). However, a reverse pattern was seen for Equ (cord mean=0.9 ng/ml, maternal mean=2.0 ng/ml). The correlations were significant between the concentration levels of Gen and Dai, Gen and Equ, and Gen and Dai plus Equ in cord serum. However, in maternal serum, the correlations were weak. Also, in 8 of 10 cord serum samples, sulfate-conjugated Gen was detected (mean=5.2 ng/ml, standard deviation=4.7), but it was detected from only one maternal serum (8.7 ng/ml). This study demonstrates placental transfer of phytoestrogens from mother to fetus. It is suggested that the metabolic and/or excretion rates of phytoestrogens are different between mother and fetus and once phytoestrogens are transferred to the fetus, they tend to stay in the fetal side longer than in the maternal side. While the implications for the health and development of the newborn are not known, these data suggest that the effects of fetal exposure to phytoestrogens should be studied further.