PubMed · 4865546
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N Hjorth, D S Wilkinson. 1968. Contact dermatitis. I.. https://doi.org/10.1111/j.1365-2133.1968.tb11909.x
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The toxic effects of Triclosan (2,4,4'-trichloro-2'-hydroxydiphenyl ether) on morphology and sexual and asexual reproduction of C. ehrenbergii were examined. In addition, the genotoxic effects of Triclosan were evaluated on the same alga using the microgel electrophoresis test, also-called Comet assay. Increasing Triclosan concentrations in the range 0.125-5 mg L(-1) did not affect size and shape of the cells but had relevant effects on both chloroplast morphology and dimension. Triclosan inhibited the vegetative growth of C. ehrenbergii at 0.5 mg L(-1). The effects on sexual reproduction indicate that the number of C. ehrenbergii zygospores was significantly reduced by the application of 0.937 mg L(-1). The Comet assay showed that Triclosan treatments led to a dose-dependent DNA damage of C. ehrenbergii; 0.25 mg L(-1)caused significant genotoxic effects and higher concentrations irreversibly altered the DNA strands. These results suggest that C. ehrenbergii could represent a useful organism to evaluate the whole toxicity of pharmaceuticals and personal care products (PPCPs), giving valuable information for a risk assessment.
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The widely used antimicrobial agent triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) readily reacts with free chlorine under drinking water treatment conditions. Overall second-order kinetics were observed, first-order in free chlorine and first-order in triclosan. Over the pH range of 4-11.5, the kinetics were pH sensitive as a result of the pH dependent speciation of both triclosan and free chlorine. Using a Marquardt-Levenberg routine, it was determined that this pH effect indicates that the dominant reaction in this system is between the ionized phenolate form of triclosan and hypochlorous acid (HOCl). The overall second-order rate coefficient was determined to be kArO- = 5.40 (+/- 1.82) x 10(3) M(-1) s(-1). Three chlorophenoxyphenols and two chlorophenols were identified by gas chromatographic-mass spectroscopic analysis. The chlorophenoxyphenol compounds include two monochlorinated triclosan derivatives (5,6-dichloro-2-(2,4-dichlorophenoy)phenol and 4,5-dichloro-2-(2,4-dichlorophenoxy)phenol) and one dichlorinated derivative (4,5,6-trichloro-(2,4-dichlorophenoxy)phenol); these species form via bimolecular electrophilic substitution of triclosan. 2,4-Dichlorophenol was detected under all reaction conditions and forms via ether cleavage of triclosan. In experiments with excess free chlorine, 2,4,6-trichlorophenol was formed via electrophilic substitution of 2,4-dichlorophenol. Chloroform formation was observed when an excess of free chlorine was present. A Hammett-type linear free-energy relationship (LFER) using Brown-Okamoto parameters (sigma+) was established to correlate the reactivity of HOCI and the phenolate forms of triclosan and other chlorophenols (log kArO- = -(10.7 +/- 2.2)Sigmasigma(+)o,m,p + 4.43). This LFER was used to obtain estimates of rate coefficients describing the reactivity of the intermediates 5,6-dichloro-2-(2,4-dichlorophenoy)phenol (kArO- approximately equal to 6 x 10(2)), 4,5-dichloro-2-(2,4-dichlorophenoxy)phenol (kArO- approximately equal to 3 x 10(2)), and 4,5,6-trichloro-(2,4-dichlorophenoxy)phenol (kArO- approximately equal to 4 x 10(1)).