Transformation kinetics of trenbolone acetate metabolites and estrogens in urine and feces of implanted steers. (November 2015)

• Record Type: Journal Article
• Authors: Blackwell, Brett R.; Johnson, Bradley J.; Buser, Michael D.; Cobb, George P.; Smith, Philip N.
• Is Part Of: Chemosphere. Volume 138(2015)
• Page Start: 901
• Page End: 907
• Publication Date: 2015-11
• Subjects: Manure-borne steroids -- Trenbolone -- Estrogens -- Biotransformation -- Aerobic degradation; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2014.10.091
• Languages: English
• ISSNs: 0045-6535

Abstract

Highlights: Steroid conjugates are rapidly converted to parent compound. 17α-Trenbolone degradation rates are lower in excreta than reported in aerobic soils. 17α-Estradiol degradation rates are lower in excreta than reported in aerobic soils. Peak estrone concentration exceeded the initial estrogen concentrations in excreta. Steroids may persist longer on feedyard surfaces than estimated from aerobic soil degradation studies. Abstract: Biotransformation of trenbolone acetate metabolites and estrogens derived from animal feeding operations in soils, waste storage systems, and in land applied manure has been well characterized. Yet recent data demonstrate potential for steroid transport into the environment directly from feedyard pens via runoff or airborne particulate matter. Therefore, the objective of this study was to determine steroid transformation rates in beef cattle excreta. Feces and urine were collected from steers recently treated with steroidal implants. Excreta were stored and periodically extracted over 112 d then analyzed for trenbolone acetate metabolites and estrogens by liquid chromatography mass spectrometry. Conjugated steroids were present primarily in urine, and conjugates quickly degraded to free steroid with a half-life of 0.6–1.0 d. The primary trenbolone acetate metabolite, 17α-trenbolone, had a half-life of 5.1–9.5 d. Likewise, 17α-estradiol was the predominant estrogen, with a half-life of 8.6–53 d. Secondary trenbolone metabolites formed from 17α-trenbolone biotransformation were observed at low concentrations less than 10% initial 17α-trenbolone concentrations. Estrone was the primary metabolite of 17α-estradiol and concentrations of estrone exceeded initial 17α-estradiol concentration in all sample types. These results suggest manure-borne steroids are more stable in excreta than in soil microcosms.