Assessment of estrogen disrupting potency in animal foodstuffs of China by combined biological and chemical analyses.

Food has been documented as one of major routes for human exposure to environmental estrogens (EEs), but information on the occurrence of EEs in animal foodstuffs is still scarce. This study analyzed estrogenic activity in 16 types of animal foodstuffs (n=142) collected from four cities (Wuhan, Guangzhou, Wenzhou and Yantai) of China by combined yeast estrogen screen (YES) bioassay and chemical analysis. By bioassay, all samples' extracts were found to induce estrogenic activities and the bioassay-derived 17β-estradiol equivalent (EEQbio) ranged from 8.29 to 118.32ng/g. In addition, the samples were analyzed by liquid chromatography coupled to tandem mass spectrometry for further chemical analysis. 17β-Estradiol was found in all samples in this survey at levels of 0.44 to 15.04ng/g. All samples had 33.1% detection rate of 17α-ethinylestradiol (EE2), and the maximum concentration was 2.80ng/g. Bisphenol A and 4-nonylphenols were detected in 83.8% and 83.1% of samples, with concentrations up to 12.56ng/g and 35.76ng/g, respectively. However, the concentrations of estrone, diethylstilbestrol and 4-t-octylphenol were found to be below the limit of detection. A comparison of EEQbio measured from the YES assay and EEQchem calculated from chemical analysis showed good correlation (R(2)=0.84). Based on the results, the YES assay can be used as a rapid pre-screening method for monitoring the levels of estrogenic activity in large numbers of animal foodstuffs, and chemical analysis used in combination can be used for the identification of specific EEs.