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ALBANESE_KATIE_A_DISSERTATION.pdf (3.94 MB)

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Photochemistry and Toxicity of Triclosan, Triclocarban, and their Photoproducts and Mixtures in Freshwater Systems

Albanese, Katie
http://rave.ohiolink.edu/etdc/view?acc_num=osu1468967416

Abstract Details

2016, Doctor of Philosophy, Ohio State University, Environmental Science.
Triclosan (TCS; 5-chloro-2-(2,4-dichlorophenoxy)phenol) and triclocarban (TCC; 3,4,4’-trichlorocarbanilide) are two antimicrobials ubiquitously found in surface waters. Many studies exist for the photolysis and toxicity of TCS, but not for TCC. Both compounds undergo photolysis, and are commonly found simultaneously in surface waters, yet effects of mixtures of these compounds to aquatic organisms are unknown. The aims of these projects are to determine the relative toxicities of TCS, TCC, and their photolysis products, all with and without dissolved organic matter (DOM), and determine the structure of any TCC photoproducts deemed important due to toxicity. The effects of mixtures of these parent compounds and photoproducts will be studied. Acute toxicities were tested using Daphnia magna in 96-hr LC50 assays for TCS, TCC, and photolyzed compounds with and without DOM in moderately hard EPA water. DOM has no impact on the toxicity of TCS (LC50 of 1.62µM (95% confidence interval (CI) 0.920-2.864) without DOM, 1.76 µM (95% CI 1.174-2.652) with DOM). TCS was significantly detoxified after photolysis (LC50s of 8.48µM (95% CI 6.681-10.77) without DOM, 8.51µM (95% CI 2.700-26.84) with DOM). The toxicity of TCC was not affected by DOM (LC50 of 0.087µM (95% CI 0.040-0.191) without DOM, LC50 of 0.147 µM (95% CI 0.050-0.434) with DOM), and TCC photolyzed in EPA water alone was significantly detoxified (LC50 of 2.67µM, 95% CI 2.067-3.443). When TCC was photolyzed with DOM the toxicity of the photoproducts did not decrease (LC50 of 0.032µM, 95% CI 0.017-0.060), indicating that DOM mediates the transformation of TCC to toxic photoproducts. Using this data, binary mixture concentrations were calculated to assess effects of these compounds and photoproducts simultaneously versus their individual effects. LC50s were the basis for toxic units (TUs), with a mixture of ½ the LC50 of one compound and ½ the LC50 of another compound representing one TU, or LC50, at which 50% mortality would be expected with additive toxicity. Mixture tests were conducted the same as single chemical tests, using a range of TUs to estimate 96-h TU50s. TU50s indicated the type of interaction between D. magna and multiple compounds versus effects of a single compound. Interactions among the compounds/photoproducts were synergistic or additive, with TU50s ranging from 0.025 to 1.45. During initial photolysis experiments differences in photolysis rates of TCS were observed in EPA vs. Milli-Q waters. To assess the reasons for these differences, kinetics of TCS photolysis were determined for waters containing single constituents of EPA water. Results indicated that bicarbonate in EPA water enhanced direct photolysis of TCS (kobs of 0.7109/min vs 0.0382/min, respectively) at pHs below its pKa. Effects of pH and bicarbonate concentration on TCS photolysis rates were tested. Results indicated bicarbonate has more influence on photolysis at higher concentrations and pHs below TCS’ pKa. To assess the role of deprotonation on TCS photolysis, methyl-triclosan (MeTCS), a non-acidic analog of TCS, was used. MeTCS was not degraded in any experiments, regardless of solution pH or bicarbonate concentration, demonstrating that bicarbonate enhances TCS photolysis via interaction with the hydroxyl group.
Roman Lanno (Advisor)
Yu-Ping Chin (Advisor)
Christopher Hadad (Committee Member)
John Lenhart (Committee Member)
191 p.
Aquatic Sciences; Chemistry; Environmental Science; Geochemistry; Toxicology
toxicology; ecotoxicology; environmental toxicology; triclosan; triclocarban; photochemistry; photolysis; environmental chemistry; photolysis products

Recommended Citations

Citations

  • Albanese, K. (2016). Photochemistry and Toxicity of Triclosan, Triclocarban, and their Photoproducts and Mixtures in Freshwater Systems [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1468967416

    APA Style (7th edition)

  • Albanese, Katie. Photochemistry and Toxicity of Triclosan, Triclocarban, and their Photoproducts and Mixtures in Freshwater Systems. 2016. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1468967416.

    MLA Style (8th edition)

  • Albanese, Katie. "Photochemistry and Toxicity of Triclosan, Triclocarban, and their Photoproducts and Mixtures in Freshwater Systems." Doctoral dissertation, Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1468967416

    Chicago Manual of Style (17th edition)

osu1468967416
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This open access ETD is published by The Ohio State University and OhioLINK.