The team found similar results for dienogest, a hormone used in a birth-control pill called Natazia, and dienedone, a banned anabolic steroid that has been marketed as a body-building supplement.
Trenbolone acetate is implanted in the ears of more than 20 million cattle in the United States, according to studies cited by the researchers in their paper.
The drug is metabolized and then excreted by livestock, and makes its way into waterways mainly through runoff.
The steroid has been considered safe due to its rapid degradation, with studies pointing to an environmental half-life of less than a day. But there has been concern that it and other synthetic drugs, when found in concentrated amounts, can be harmful to aquatic species and the environment generally. Studies have pointed to steroids and other drugs' effects on fish, through fewer eggs produced by females to skewing the sex of some species.
"We rarely see fish kills anymore, and we probably aren't discharging many carcinogens into surface waters anymore. But I don't believe this necessarily means that our water is safe for aquatic organisms," says Edward Kolodziej, associate professor in engineering at the University of Nevada-Reno and the other corresponding author on the Science paper. "It just might be harder to characterize the adverse effects associated with contaminant exposures these days."
Sunlight is one catalyst for breaking down compounds in the environment. But in this study, by simulating day and night in the lab, the research team found that the steroid's chemical compounds never fully disappeared in daylight. Moreover, during a simulated night, under typical surface water conditions, some of the compounds regenerated
|Contact: Richard Lewis|
University of Iowa