title: Coupled reversion and stream-hyporheic exchange processes increase environmental persistence of trenbolone metabolites.
abstract: Existing regulatory frameworks for aquatic pollutants in the United States are idealized, often lacking mechanisms to account for contaminants characterized by (1) bioactivity of both the parent and transformation products and (2) reversible transformations (that is, metastable products) driven by chemical or physical heterogeneities. Here, we modelled a newly discovered product-to-parent reversion pathway for trenbolone acetate (TBA) metabolites. We show increased exposure to the primary metabolite, 17α-trenbolone (17α-TBOH), and elevated concentrations of the still-bioactive primary photoproduct hydroxylated 17α-TBOH, produced via phototransformation and then converted back to 17α-trenbolone in perpetually dark hyporheic zones that exchange continuously with surface water photic zones. The increased persistence equates to a greater potential hazard from parent-product joint bioactivity at locations and times when reversion is a dominant trenbolone fate pathway. Our study highlights uncertainties and vulnerabilities with current paradigms in risk characterization.
authors.affiliation: School of Public and Environmental Affairs, Indiana University, Bloomington, Indiana 47405, USA.
authors.forename: Adam S
authors.identifier: 0000000263760061
authors.initials: AS
authors.lastname: Ward
authors.affiliation: Department of Civil &Environmental Engineering, The University of Iowa, Iowa City, Iowa 52242, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Cwiertny
authors.affiliation: 1] Interdisciplinary Arts and Sciences, University of Washington, Tacoma, Tacoma, Washington 98402, USA [2] Department of Civil &Environmental Engineering, University of Washington, Seattle, Washington 98195, USA.
authors.forename: Edward P
authors.initials: EP
authors.lastname: Kolodziej
authors.affiliation: Department of Civil &Environmental Engineering, The University of Iowa, Iowa City, Iowa 52242, USA.
authors.forename: Colleen C
authors.initials: CC
authors.lastname: Brehm
mesh_terms: D017753:Ecosystem; D004777:Environment; D012307:Risk Factors; D045483:Rivers / Q000737:chemistry*; D013997:Time Factors; D014204:Trenbolone Acetate / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D014204:Trenbolone Acetate