Study: Cattle hormones more environmentally damaging than previously thought


Iowa ranks 7th in the nation
The USDA reports there were approximately 3,800,000 head of cattle in Iowa in 2014. (Brad Smith/Flickr)

Nick Fetty | May 14, 2015

Hormones used to beef up cattle could be causing more environmental damage than once thought, according to a recent study in the journal Nature Communications.

The study – which was co-authored by University of Iowa environmental engineering professor David Cwiertny – found hormones associated with cattle production “persist in the environment at higher concentrations and for longer durations than previously thought.” The hormones eventually end up in streams and rivers which has affected the reproductive health and behavioral patterns of fish and other aquatic life.

“We’re releasing this into the environment at levels that are potentially problematic for the ecosystem,” said Adam Ward, lead author of the study. “If you’re an amphibian, a fish, a minnow, you spend your whole life being bathed in this sort of low dose of testosterone.”

The researchers examined trenbolone acetate (or TBA) which speeds up muscle growth in cattle and has been used in the industry for about 20 years. When the TBA is metabolized it breaks down into a compound known as 17-alpha-trenbolone which then runs off into waterways.

The study is a follow up to research Cwiertny published in 2013 which suggested that when 17-alpha-trenbolone was exposed to sunlight it broke down and resulted in lower concentrations in waterways however the most recent research now suggests that the compound doesn’t break down as much as previously thought.

According data from the USDA National Agricultural Statistical Service, Iowa ranks 7th in the nation for cattle production.

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