Presence and Fate of Steroid Hormones in a Colorado River

In river systems, steroid hormones have been linked to various adverse effects on fish, including altered sex ratios, intersex fish, and diminished reproduction. Sources of steroid hormones in surface waters include discharges from wastewater treatment plants (WWTPs), runoff from agricultural feeding operations, and runoff from agricultural fields where manure and biosolids are applied as fertilizers. The presence of steroid hormones in Colorado's Cache la Poudre River water is being investigated by solid-phase extraction, derivatization, and gas chromatography–tandem mass spectrometry. Multiple-reaction monitoring and isotope dilution procedures are being used for improved sensitivity and reliable compound quantification. Laboratory experiments also are being conducted to investigate the potential for steroid hormone biodegradation and photodegradation under simulated natural conditions, including experiments to investigate the potential for indirect photodegradation through reactions with nitrate and humic acid (acting as photosensitizers). Estrogens and androgens were observed at multiple sites along the river. Biodegradation of testosterone by manure-borne microorganisms in stud boar pig manure was observed. Using UV-A lamps (i.e., λ > 315 nm), direct photodegradation of testosterone and progesterone was observed, and indirect photodegradation of testosterone and 17β-estradiol was observed in the presence of 5 mg/L humic acid. These findings suggest that steroid hormones are present in the Cache la Poudre River, and have the potential to undergo biodegradation and photodegradation. These findings also suggest that humic acid (acting as a photosensitizer) can facilitate the indirect photodegradation of some steroid hormones.