An anabolic steroid typically used to beef up cattle was found not to have broken down in rivers and streams, like scientists previously thought, when the sun went down. Known as trenbolone, the steroid’s pH levels in the absence of sunlight allow it to stray from its dormant state and “reawake,” leading researchers to dub it the “vampire steroid.”

The U.S. Food and Drug Administration (FDA) has approved trenbolone for use among cattle; however, due to its classification as a schedule III controlled substance, it is banned for human consumption. Scientists once believed the drug degraded in water supplies through a process known as phototransformation. Now, a recent study has found trenbolone resurfaces in the water when the sun goes down, contaminating local water supplies and damaging the reproductive process of much aquatic life.

Cattle that are fed trenbolone will often dispose of the steroid in their feces. As it’s dispersed through natural means, the excrement spreads through the surrounding environment and eventually lands in nearby water supplies. In the latest study, researchers evaluated trenbolone levels according to various pH levels and temperatures in the water.

“Unexpectedly, we observed that the rapid photohydration of TBA (trenbolone acetate) metabolites is reversible under conditions representative of surface waters (pH 7, 25°C),” states the report, which was published in the journal Science. “This product-to-parent reversion mechanism results in unique diurnal cycling and substantial regeneration of TBA metabolites at rates that are strongly temperature- and pH-dependent.”

Effectively, the pH balance and temperature of the water reorient in such a way at night as to allow the steroid to reform. This is potentially alarming because prior tests have typically evaluated the substance’s presence only in daytime conditions.

“The vast majority of routine water quality monitoring does not examine these unregulated contaminants,” Bryan Brooks, director of the Environmental Health Science program at Baylor University, who was not involved with the study, told Healthline. “And if pharmaceuticals are examined in water bodies, sampling typically occurs during daylight hours and often only examines water samples from the surface of lakes and streams. Such a practice could over- or underestimate risks of various pharmaceuticals.”

Herein lies the danger in missing trenbolone’s vampiric re-formation. Prescription drugs and other medicines are evaluated and regulated based on empirical tests of safety. When those tests degrade in quality, through certain methodological flaws, the safety of the drugs themselves gets called into question.

“Reports from this paper may stimulate rethinking the timing of environmental monitoring and surveillance,” Brooks added.

To better understand the steroid’s re-formation properties, scientists must monitor its behavior over continuous periods — stretches of up to 48 hours, according to one of the study’s authors, David Cwiertny, who also works as a scientist at University of Iowa's Department of Civil and Environmental Engineering.

Cwiertny remarked to Healthline that trenbolone’s recently discovered unpredictability could make it far more of a threat in waters near agricultural sites than previously thought.

“There's a high degree of uncertainty in the existing occurrence data because of the trends we see,” he said, noting the steroid’s presence is probably “far more persistent than all our models currently predict.”

But while scientists see little direct threat to humans, aquatic life could face the most glaring danger.

“More research is needed to increase our knowledge and understanding of the fate of drugs in surface waters, their products of degradation, the complex issues of mixtures, and the role of environmental monitoring,” states a 2006 report from Environmental Science and Technology.

This will require, among other things, open lines of communication between the scientific community and a broader consumer audience.

Source: Qu S, Kolodziej E, Long S. Product-to-Parent Reversion of Trenbolone: Unrecognized Risks for Endocrine Disruption. Science. 2013.