Environmental photochemical fate and UVC degradation of sodium levothyroxine in aqueous medium
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The synthetic hormone sodium levothyroxine (LTX) is one of the most prescribed drugs in the world and the most effective in hypothyroidism treatment. The presence of LTX in the environment has become a matter of major concern due to the widespread use of this hormone and by the fact that it is only partially removed in conventional water and sewage treatment plants. However, information regarding the photochemical fate of this hormone in environmental or engineered systems is scarce in the literature. In this work, the sunlight-driven direct and indirect LTX degradation was investigated by determining the photolysis quantum yield, ΦLTX = 3.80 (± 0.02) × 10−5, as well as the second-order kinetic constants of the reactions with hydroxyl radicals, kLTX,•OH = 1.50 (± 0.01) × 1010 L mol−1 s−1 and singlet oxygen, kLTX,1O2 = 1.47 (± 0.66) × 108 L mol−1 s−1. Mathematical simulations indicate that LTX photodegradation is favored in shallow, nitrite-rich, and dissolved organic matter (DOM)-poor environments, with LTX half-life times varying from less than 10 days to about 80 days. LTX removals of 85 and 95% were achieved by UVC photolysis and UVC/H2O2 after 120 min, respectively. Three transformation products, triiodothyronine, diiodothyronine, and diiodotyrosine, were identified during LTX degradation by the UVC-based processes studied. The results herein regarding photo-induced kinetics coupled with environmental fate simulations may help evaluate LTX persistence and also the design of water and wastewater treatment processes.
KeywordsSodium levothyroxine Environmental photochemical fate Advanced oxidation processes Endocrine disruptors Reactive oxygen species Mathematical simulations
The authors thank the Coordination for the Improvement of Higher Education Personnel (CAPES) and the São Paulo Research Foundation (FAPESP, grant #2013/50218-2) for the financial support.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no competing interests.
- ANVISA (2017) Brazilian health regulatory agency. Statistical Book of Pharmaceutical Market, BrazilGoogle Scholar
- Bianco A, Fabbri D, Minella M, Brigante M, Mailhot G, Maurino V, Minero C, Vione D (2015) New insights into the environmental photochemistry of 5-chloro-2-(2,4- dichlorophenoxy)phenol (triclosan): reconsidering the importance of indirect photoreactions. Water Res 72:271–280. https://doi.org/10.1016/j.watres.2014.07.036 CrossRefGoogle Scholar
- Box GEP, Hunter WG, Hunter JS (1978) Statistics for experimenters: an introduction to design, data analysis and model building. Wiley, New YorkGoogle Scholar
- Fabbri D, Minella M, Maurino V, Minero C, Vione D (2015) Photochemical transformation of phenylurea herbicides in surface waters: a model assessment of persistence, and implications for the possible generation of hazardous intermediates. Chemosphere 19:601–607. https://doi.org/10.1016/j.chemosphere.2014.07.034 CrossRefGoogle Scholar
- Harris DC (2003) Quantitative chemical analysis, 6th edn. W.H. Freeman and Co., New YorkGoogle Scholar
- Ianiro G, Mangiola F, Di Rienzo TA, Bibbò S, Franceschi F, Greco AV, Gasbarrini A (2014) Levothyroxine absorption in health and disease, and new therapeutic perspectives. Eur Rev Med Pharmacol Sci 18:451–456Google Scholar
- Laurentiis E, Minella M, Brodato M, Maurino V, Minero C, Vione D (2013) Modeling the photochemical generation kinetics of 2-methyl-4-chlorophenol, an intermediate of the herbicide MCPA (2 methyl-4-chlorophenoxyacetic acid) in surface waters. Aquat Ecosyst Health Manag 16:216–221. https://doi.org/10.1080/14634988.2013.788433 CrossRefGoogle Scholar
- Marchetti G, Minella M, Maurino V, Minero C, Vione D (2013) Photochemical transformation of atrazine and formation of photointermediates under conditions relevant to sunlit surface waters: laboratory measures and modelling. Water Res 47:6211–6222. https://doi.org/10.1016/j.watres.2013.07.038 CrossRefGoogle Scholar
- Oppenlander T (2003) Photochemical purification of water and air: advanced oxidation processes (AOPs): principles, reaction mechanisms, reactor concepts, 1st edn. Wiley-VCH, WeinheimGoogle Scholar
- Schwarzenbach RP (2003) Environmental organic chemistry, Second edn. Wiley & Sons, Inc., HobokenGoogle Scholar
- Vione D, Das R, Rubertelli F, Maurino V, Minero C, Barbati S, Chiron S (2010) Modelling the occurrence and reactivity of hydroxyl radicals in surface waters: implications for the fate of selected pesticides. Int J Environ Anal Chem 90:260–275. https://doi.org/10.1080/03067310902894218 CrossRefGoogle Scholar
- Vione D (2014) A test of the potentialities of the APEX software (Aqueous Photochemistry of Environmentally occurring Xenobiotics). Modelling the photochemical persistence of the herbicide cycloxydim in surface waters, based on literature kinetic data. Chemosphere 99:272–275. https://doi.org/10.1016/j.chemosphere.2013.10.078
- Zacarías VHR, Velázquez Machuca MA, Montañez Soto JL, Pimentel Equihua JL, Vallejo Cardona AA, López Calvillo MD, Venegas González J (2017) Hydrochemistry and emerging pollutants in urban industrial wastewater in Morelia, Michoacán, Mexico. Rev Int Contam Ambient 33:221–235. https://doi.org/10.20937/RICA.2017.33.02.04 CrossRefGoogle Scholar