Persistence and fate of 17β-estradiol and testosterone in agricultural soils

Steroidal hormones are constantly released into the environment by man-made and natural sources. The goal of this study was to examine the persistence and fate of 17 beta-estradiol and testosterone, the two primary natural sex hormones. Incubation experiments were conducted under aerobic and anaerobic conditions using [4-C-14]-radiolabeled 17 beta-estradiol and testosterone. The results indicated that 6% of 17 beta-estradiol and 63% of testosterone could be mineralized to (CO2)-C-14 in native soils under aerobic conditions. In native soils under anaerobic conditions, 2% of testosterone and no 17 beta-estradiol was methanogenized to (CH4)-C-14. Essentially, no mineralization of either testosterone or 17 beta-estradiol to (CO2)-C-14 occurred in autoclaved soils under aerobic or anaerobic condition. Results also indicated that 17 beta-estradiol could be transformed to an unidentified polar compound through abiotic chemical processes; however, 17 beta-estradiol was only oxidized to estrone via biological processes. The TLC results also indicated that testosterone was degraded, not by physical-chemical processes but by biological processes. Results also indicated that the assumed risks of estrogenic hormones in the environment might be over-estimated due to the soil's humic substances, which can immobilize majority of estrogenic hormones, and thereby reduce their bioavailability and toxicity. (c) 2006 Elsevier Ltd. All rights reserved.