Environmental estrogens in an urban aquatic ecosystem: I. Spatial and temporal occurrence of estrogenic activity in effluent-dominated systems

• Environmental estrogens are ubiquitous in the Chicago area waterways.
• Environmental estrogen distribution did not follow upstream/downstream gradients.
• General use waters had lower estrogenicity than secondary contact waters.
• Estrogenicity of the waterways did not correlate with water quality parameters.
• Runoff and combined sewer overflow contribute to estrogenicity of Chicago waters.

The present study investigated occurrence of environmental estrogens (EEs) in waterways managed by the Metropolitan Water Reclamation District of Greater Chicago (‘District’) — one of the largest and most complex water districts in the United States. The objectives of the study were: (i) to document spatial and temporal occurrence of EEs in the Chicago Area Waterways (CAWs); (ii) to determine whether water reclamation plant (WRP) effluents contribute to estrogenic pollution of the receiving streams; (iii) to determine whether the mandated water quality monitoring data could be used to predict estrogenic pollution in the receiving streams; and (iv) to determine whether snow melt, storm runoff and combined sewer overflows may also be contributors of estrogenic activity to these systems. The estrogenic potency of the waterways was assessed using a cell-based reporter gene assay. The water quality data was readily available as part of the District's regular monitoring program. Our findings indicate that EEs are commonly found in the CAWs, and that WRP effluents are one of, but not the only important contributor to estrogenic activity. Mean estrogenic activities in CAWs (11 ng estradiol equivalents (EEQs/L)) are well within the values reported for other urban areas and WRP effluents. The estrogenic activity exhibited significant seasonal variation with highest values noted during the spring and summer months. When comparing the mean estrogenic activity of general use waters, secondary contact waters and WRP effluents, we found that general use waters had significantly lower estrogenic activity (ca 5 ng EEQ/L) than the other two matrices (ca 15 and 17 ng EEQ/L respectively). Our analyses indicate that estrogenic activity of the waterways was not reliably associated with mandated water quality parameters, and that such measurements may not be useful for predicting estrogenic activity, especially so in the complex urban systems. One of the prominent findings of this study is that EEs do not follow predictable spatial patterns — many of the upstream sites in the heavily urbanized areas had levels of estrogenic activity comparable to those found in the effluents and downstream locations. Our data suggest that surface runoff and snow melt are estrogenic (0–9 ng EEQ/L), and given that their estrogenic activities are similar to those of their receiving waterways (0–7 ng EEQ/L), we conclude that these non-WRP sources are important contributors to estrogenic activity of the CAWs.