Trenbolone Acetate Metabolite Transport in Rangelands and Irrigated Pasture: Observations and Conceptual Approaches for Agro-Ecosystems

Abstract

To assess the relative ecological risks of trenbolone acetate (TBA) use in agro-ecosystems, we evaluated the spatiotemporal dynamics of TBA metabolite transport during irrigation and rainfall events. Within a pasture, TBA-implanted heifers (40 mg TBA, 8 mg estradiol) were briefly penned (24 h) at high stocking densities (500 animal units (AU)/ha), prior to irrigation. Irrigation runoff concentrations of 17α-trenbolone (17α-TBOH) 0.3 m downslope were 11 ng/L in the wetting front, but quickly decreased to ∼0.5 ng/L, suggesting mass transfer limitations to transport. At 3 and 30 m downslope, efficient attenuation of 17α-TBOH concentrations is best explained by infiltration and surface partitioning. At plot scales, transport through vegetated filter strips resulted in <0.5-7 ng/L 17α-TBOH concentrations in rainfall-induced runoff with partial subsequent attenuation. Thus, even under intense grazing scenarios, TBA-metabolite transport potential is expected to be low in rangelands, with ecological risks primarily arising from uncontrolled animal access to receiving waters. However, 17α-TBOH concentrations in initial runoff were predicted to exceed threshold levels (i.e., no observed adverse effect levels [NOAELs]) for manure concentrations exceeding 2.0 ng/g-dw, which occurs throughout most of the implant life. For comparison, estrone and 17β-estradiol were modeled and are likely capable of exceeding NOAELs by a factor of ∼2-5 in irrigation runoff, suggesting that both endogenous and exogenous steroids contribute to endocrine disruption potential in agro-ecosystems.

Rates and product identification for trenbolone acetate metabolite biotransformation under aerobic conditions

“…Samples were resuspended in 100 mL N-methyl-N-(trimethylsilyl)-trifluoroacetamine, capped prior to incubation (40 min) at 60 8C, then cooled and analyzed by GC-MS/MS with isotopic dilution analysis. At these microcosm volumes, the method limit of quantification was 14 ng/L, and quality assurance and quality control metrics (near quantitative spike recovery, precision generally within 10%, no false positives detected in blanks) are similar to those we reported in detail for concurrent studies [11,25,26]. Samples that failed either to meet this limit of quantification or to meet a signal-to-noise ratio of 10 were excluded from quantitative analysis.…”

Surface and subsurface attenuation of trenbolone acetate metabolites and manure-derived constituents in irrigation runoff on agro-ecosystems

“…S2 †). [42][43][44][45][46][47] The tank was placed upslope of the soil trench or VFS system and lled with irrigation water (Browns Valley Irrigation District; pH ¼ 7.6, DOC ¼ 5.7 AE 0.1 mg L À1 ). Prior to experiments, the solution was allowed to equilibrate for 24 hours (Fig.…”

A critical review of the environmental occurrence and potential effects in aquatic vertebrates of the potent androgen receptor agonist 17β‐trenbolone

“…Another runoff study, which featured a 2‐yr monitoring program, recorded a maximum measured concentration of 17β‐trenbolone of 270 ng/L, whereas 17α‐trenbolone was not detected (Bartelt‐Hunt et al ). Both the Gall et al () and Bartelt‐Hunt et al () studies are in contrast with other simulated cattle‐dosing studies, where concentrations of 17α‐trenbolone were consistently higher than 17β‐trenbolone in wastes originating from dosed animals (Webster et al ; Jones et al , , ).…”

“…The principal route of 17b-trenbolone entering the environment is through runoff of wastes (urine and feces) from livestock dosed with trenbolone acetate (Lange et al 2002;Kolok and Sellin 2008;Snow et al 2013;Jones et al 2014bJones et al , 2014c. Hence, aquatic species would be most prone to unintended exposures.…”