These effluent concentrations from MTP and ATS discharges were generally consistent with previous literature for municipal effluents. Belfroid et al. (1999) reported E1 and E2 median concentrations of 0.9 and 4.5 ng L1, respectively, in
effluents of five wastewater treatment plants in the Netherlands. In the same study, E2 and EE2 concentrations for most of the effluent samples were reported to be below the limits of detection. In a study comparing the steroid estrogens from 17 MTPs across Europe, Johnson et al. (2005) reported that E2 concentrations were usually below the detection limit, and EE2 was detected in only one of the MTPs samples at 1.1 ng L1.