Degradation and transformation of 17α‐trenbolone in aerobic water–sediment systems

Synovex® ONE is an extended‐release implant containing the active ingredients estradiol benzoate and trenbolone acetate for use in beef steers and heifers. Trenbolone acetate is rapidly hydrolyzed in cattle to form 17β‐trenbolone and its isomer, 17α‐trenbolone, which are further transformed to a secondary metabolite, trendione. As part of the environmental assessment for the use of Synovex ONE, data were generated to characterize the fate of 17α‐trenbolone, which is the principal metabolite found in cattle excreta, in the environment. A study was conducted to determine the degradation and transformation of [14C]‐17α‐trenbolone in 2 representative water–sediment systems under aerobic conditions. The same transformation products, 17β‐trenbolone and trendione, were formed, principally in the sediment phase, in both systems. From the production of these transformation products, the 50% disappearance time (DT50) values of 17β‐trenbolone and trendione were determined, along with the DT50 values of the parent compound and the total drug (17α‐trenbolone + 17β‐trenbolone + trendione). The DT50 values for the total system (aqueous and sediment phase) and for the total residues (17α‐trenbolone + 17β‐trenbolone + trendione) in the 2 systems were 34.7 d and 53.3 d, respectively. Environ Toxicol Chem 2017;36:630–635. © 2016 SETAC