Journal article
Phototransformation rates and mechanisms for synthetic hormone growth promoters used in animal agriculture
Environmental science & technology, Vol.46(24), pp.13202-13211
12/18/2012
DOI: 10.1021/es303091c
PMID: 23163486
Abstract
Trenbolone acetate, melengestrol acetate, and zeranol are synthetic hormones extensively used as growth promoters in animal agriculture, yet despite occurrence in water and soil little is known about their environmental fate. Here, we establish the time scales and mechanisms by which these synthetic growth promoters and their metabolites (SGPMs) undergo phototransformation in sunlit surface waters. The families of trenbolone acetate (including 17β-trenbolone, 17α-trenbolone, and trendione) and melengestrol acetate (including melengestrol) readily undergo direct photolysis, exhibiting half-lives between ∼0.25 and 1 h in both natural and simulated sunlight that were largely insensitive to solution variables (e.g., pH, temperature, and cosolutes). Direct photolysis yielded products that not only are more photostable but also maintain their steroidal ring structure and therefore may retain some biological activity. In contrast, zeranol, β-zearalanol, and zearalanone only exhibited reactivity in irradiated solutions of model humic and fulvic acids, and rates of indirect photolysis increased steadily from pH 7 to 9. Use of selective probe and quencher compounds suggest hydroxyl radical and triplet state dissolved organic matter are responsible for zeranol family decay at neutral pH, although singlet oxygen contributes modestly in more alkaline waters. This observed pH-dependence appears to result from photooxidants reacting primarily with the monodeprotonated form of zeranol (pK(a) values of 8.44 and 11.42). This investigation provides the first characterization of the fate of this emerging pollutant class in sunlit surface waters and prioritizes future efforts on the identity, fate, and biological impact of their more persistent phototransformation products.
Details
- Title: Subtitle
- Phototransformation rates and mechanisms for synthetic hormone growth promoters used in animal agriculture
- Creators
- Shen Qu - Department of Civil and Environmental Engineering, University of Iowa, 4105 Seamans Center, Iowa City, Iowa 52242, USAEdward P KolodziejDavid M Cwiertny
- Resource Type
- Journal article
- Publication Details
- Environmental science & technology, Vol.46(24), pp.13202-13211
- Publisher
- United States
- DOI
- 10.1021/es303091c
- PMID
- 23163486
- ISSN
- 1520-5851
- eISSN
- 1520-5851
- Language
- English
- Date published
- 12/18/2012
- Academic Unit
- Center for Health Effects of Environmental Contamination; Civil and Environmental Engineering; Public Policy Center (Archive); Chemical and Biochemical Engineering
- Record Identifier
- 9983991978602771
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