Detecting Endocrine Disrupting Compounds in Various Waste Matrices Using Bioassays

Endocrine disrupting compound (EDC) concentrations in sludges generated by public owned treatment works ( POTWs) are rarely studied, although sorption to solids is a likely fate. Beyond domestic wastewater treatment, wastes generated by animal agriculture may significantly contribute to the introduction of EDCs into the environment. Waste products from both these industries reflect complex matrices and present a significant challenge for achieving accurate EDC measurements. The purpose of this study was to compare two different EDC extraction methods and two different EDC bioassays on various sample matrices from concentrated animal feeding operation (CAFO) dairy farm wastes and digested municipal sludges. The two extraction methods studied in this research were a two-step base-toluene extraction and a one-step cyclohexane extraction. The two bioassays assessed were an enzyme-linked immunosorbent assay (ELISA) and the yeast estrogen strain (YES) assay, slightly modified from that used by others. Estrogenic activity was measured directly as 17β-estradiol (E2) through the ELISA method or as E2 equivalents (E2-eq) when measured with the YES assay. Both extraction methods yielded reasonable recoveries from distilled water in the absence of matrix interferences; however, recoveries from samples depended significantly on the source of the sample and the method of EDC determination. The YES assay detected much higher estrogenic activities in diary farm slurry samples compared to the ELISA assay. This higher detection by YES assay was also found in anaerobically and aerobically digested sludges from a POTW. The two-step base-solvent extraction, compared to the one-step cyclohexane extraction, yielded higher E2 concentrations in the dairy farm wastes. However, cyclohexane extraction yielded a higher E2-eq in both anaerobic and aerobic sludges analyzed by YES; the same was not seen for ELISA. These results suggest that waste matrices vary sufficiently so that method optimization needs to be performed for EDC assays applied to them.