Statewide Survey of Hormones and Antibiotics in Surface Waters of Delaware

Water-quality surveys have confirmed the presence of hormones and antibiotics in surface waters of the United States, which may be of concern to aquatic life. We investigated the concentrations of hormones and antibiotics in surface waters of the state of Delaware to determine how they compared against environmental thresholds, how they varied across the state, and if they were correlated with land use type. Fifty surface water locations were sampled during early spring and late summer. Water samples were initially screened with ELISA followed by analysis with LC/MS/MS. The measured ranges of hormone concentrations were: 0-3.71ng/l for estrone, 0-4.65ng/l for estrone-3-sulfate, and 0-6.27ng/l for 17-estradiol. The measured ranges of antibiotics were: 0-3.30ng/l for sulfamerazine, 0-10.74ng/l for sulfamethoxazole, and 0-2.29ng/l for tetracycline. The predicted no-effect concentration (PNEC) for estrone was exceeded for three samples and the PNEC for 17-estradiol was exceeded for 11 samples. In general, concentrations and detection frequencies were lower in the summer than the spring. The highest concentrations of hormones and antibiotics were spatially distributed in agricultural and urban areas; however, the correlations between land use type and the concentrations were weak. This study was the first statewide survey of hormones and antibiotics for Delaware and provided important baseline data on these emerging contaminants.