DEGRADATION AND TRANSFORMATION OF 17α-ESTRADIOL IN WATER-SEDIMENT SYSTEMS UNDER CONTROLLED AEROBIC AND ANAEROBIC CONDITIONS

One of the principal metabolites in cattle excreta following the administration of Synovex((R)) ONE, which contains estradiol benzoate and trenbolone acetate, is 17 alpha-estradiol. As part of the environmental assessment of the use of Synovex ONE, data were generated to characterize the fate of 17 alpha-estradiol in the environment. Studies were conducted to determine the degradation and transformation of 17 alpha-[C-14]-estradiol in 2 representative water-sediment systems each under aerobic and anaerobic conditions. The same transformation products-estriol, 17 beta-estradiol, and estrone-were formed, principally in the sediment phase, under both conditions in both systems. From the production of these transformation products, the 50% disappearance time (DT50) values of estrone and 17 beta-estradiol were determined, along with the DT50 values of 17 alpha-estradiol and the total drug (17 alpha-estradiol+17 beta-estradiol+estrone). The results indicate that 17 alpha-[C-14]-estradiol was more persistent under anaerobic conditions than under aerobic conditions and that 17 alpha-[C-14]-estradiol was less persistent than its transformation products. The DT50 values for the total system (aqueous and sediment phases) and for the total residues (17 alpha- estradiol, 17 beta-estradiol, and estrone) were selected for use in modeling the environmental fate of estradiol benzoate. For aerobic degradation in the water-sediment system, the DT50 was 31.1 d, and it was 107.8 d for the anaerobic system. (C) 2016 SETAC