Steroids used to boost growth in cattle may endure in water longer than expected, a new study finds.
It was widely believed that certain steroids and other drugs quickly degrade once they're discharged into waterways and the ecological threat they pose declines.
But this study found that the anabolic steroid trenbolone acetate and two other drugs may transform in a way that raises questions about their impact on the environment. Trenbolone is used to promote weight gain and increase feeding efficiency in cattle. It was once popular among bodybuilders and weightlifters but is no longer allowed to be used in humans.
In lab tests and field experiments, researchers found that trenbolone does not fully break down in water as previously believed. Instead, it retains enough of a chemical residue to regenerate itself under certain conditions, according to the study published in the journal Science.
Runoff into waterways
Research indicates that trenbolone is implanted in the ears of more than 20 million cattle in the United States. The drug is eventually excreted by livestock and makes its way into waterways, mainly through runoff.
"We're finding a chemical that is broadly utilised, to behave in a way that is different from all our existing regulatory and risk-assessment paradigms," study corresponding author David Cwiertny, an assistant professor in engineering at the University of Iowa, said in a university news release.
"What our work hopefully will do is help us better understand and assess the environmental fate of emerging contaminant classes. There are a variety of bioactive pharmaceuticals and personal-care products that we know are present in trace amounts in our water supply. We should use what we're learning about trenbolone to more closely scrutinise the fate and better mitigate the impact of these products in the environment," he explained.
The researchers also found similar results for dienogest, a hormone used in a birth control pill called Natazia, and for dienedone, a banned anabolic steroid that had been sold as a body-building supplement.
The U.S. National Institute on Drug Abuse has more about anabolic steroids.