Triclosan: environmental exposure, toxicity and mechanisms of action. J Appl Toxicol

Department of Biological Sciences, Alberta Water and Environmental Science Bldg, 4401 University Dr. W., University of Lethbridge, Lethbridge, Alberta, Canada.
Journal of Applied Toxicology (Impact Factor: 3.17). 05/2011; 31(4):285-311. DOI: 10.1002/jat.1660
Source: PubMed

ABSTRACT Triclosan [5-chloro-2-(2,4-dichlorophenoxy)phenol; TCS] is a broad spectrum antibacterial agent used in personal care, veterinary, industrial and household products. TCS is commonly detected in aquatic ecosystems, as it is only partially removed during the wastewater treatment process. Sorption, biodegradation and photolytic degradation mitigate the availability of TCS to aquatic biota; however the by-products such as methyltriclosan and other chlorinated phenols may be more resistant to degradation and have higher toxicity than the parent compound. The continuous exposure of aquatic organisms to TCS, coupled with its bioaccumulation potential, have led to detectable levels of the antimicrobial in a number of aquatic species. TCS has been also detected in breast milk, urine and plasma, with levels of TCS in the blood correlating with consumer use patterns of the antimicrobial. Mammalian systemic toxicity studies indicate that TCS is neither acutely toxic, mutagenic, carcinogenic, nor a developmental toxicant. Recently, however, concern has been raised over TCS's potential for endocrine disruption, as the antimicrobial has been shown to disrupt thyroid hormone homeostasis and possibly the reproductive axis. Moreover, there is strong evidence that aquatic species such as algae, invertebrates and certain types of fish are much more sensitive to TCS than mammals. TCS is highly toxic to algae and exerts reproductive and developmental effects in some fish. The potential for endocrine disruption and antibiotic cross-resistance highlights the importance of the judicious use of TCS, whereby the use of TCS should be limited to applications where it has been shown to be effective.

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    • "Moreover, their effects on zebrafish embryos were already studied within our group (Domingues et al., 2013, 2010; Oliveira et al., 2009). TCS is a common bactericide used in oral care products, acrylic products, plastic materials and cosmetics (Dann and Hontela, 2011) and has been frequently found in the environment. Singer et al. (2002) observed concentrations ranging from 42 to 213 ng L À 1 downstream of several sewage treatment plants in Switzerland. "
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    ABSTRACT: At ecosystems level, environmental parameters such as temperature, pH, dissolved oxygen concentration and intensity of UV radiation (UVR) have an important role on the efficiency of organisms' physiological and behavioral performances and consequently on the capacity of response to contaminants. Insignificant alterations of these parameters may compromise this response. In addition, these parameters can additionally alter chemical compounds by inducing their degradation, producing thereafter other metabolites. Understanding the combined effects of chemicals and environmental parameters is absolutely necessary for an adequate prediction of risk in aquatic environments. According to this scenario, this work aims at studying the combined toxicity of UVR and three xenobiotics: the biocide triclosan (TCS), the metal chromium (as potassium dichromate, PD) and the fungicide prochloraz (PCZ). To achieve this goal zebrafish (Danio rerio) embryos (3h post fertilization (hpf)) were exposed to several concentrations of each chemical combined with different UV intensities; mortality and eggs were recorded every 24h for the all test duration (96h). Results showed different response patterns depending on the toxicant, stress levels and duration of exposure. The combination of UVR and TCS indicated a dose ratio deviation where synergism was observed when UVR was the dominant stressor (day 2). The combination of UVR and PD presented a dose level dependency at day 3 indicating antagonism at low stress levels, changing with time where at day 4, a dose ratio deviation showed statistically that synergism occurred at higher PD concentrations. Finally, UVR combined with PCZ indicated a dose ratio at day 3 and dose level deviation at day 4 of exposure, suggesting a synergistic response when PCZ is the dominant stressor in the combination. The obtained results in this study highlighted the importance of taking into account the possible interaction of stressors and time of exposure to better predict environmental risk. Copyright © 2015 Elsevier Inc. All rights reserved.
    Ecotoxicology and Environmental Safety 07/2015; 122:145-152. DOI:10.1016/j.ecoenv.2015.07.021 · 2.48 Impact Factor
    • "Despite regulatory action in the 1970s, trace residues of these chemicals are still present at appreciable concentrations in aquatic systems (Conka et al., 2014; Lohmann et al., 2012; Nomiyama et al., 2010). More recently, studies have demonstrated the potential environmental risks posed by emerging organic contaminants (EOCs), including halogenated flame retardants (HFRs), synthetic musks, and methyl triclosan, a degradation product of the common bactericide, triclosan (Brausch and Rand, 2011; Buerge et al., 2003a; Dann and Hontela, 2011; de Wit, 2002; Lam et al., 2009; Nakata et al., 2007; Stapleton et al., 2011). "
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    ABSTRACT: A gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) based method was developed for determination of 86 hydrophobic organic compounds in seawater. Solid-phase extraction (SPE) was employed for sequestration of target analytes in the dissolved phase. Ultrasound assisted extraction (UAE) and florisil chromatography were utilized for determination of concentrations in suspended sediments (particulate phase). The target compounds included multi-class hydrophobic contaminants with a wide range of physical-chemical properties. This list includes several polycyclic and nitro-aromatic musks, brominated and chlorinated flame retardants, methyl triclosan, chlorobenzenes, organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). Spiked MilliQ water and seawater samples were used to evaluate the method performance. Analyte recoveries were generally good, with the exception of some of the more volatile target analytes (chlorobenzenes and bromobenzenes). The method is very sensitive, with method detection limits typically in the low parts per quadrillion (ppq) range. Analysis of 51 field-collected seawater samples (dissolved and particulate-bound phases) from four distinct coastal sites around Singapore showed trace detection of several polychlorinated biphenyl congeners and other legacy POPs, as well as several current-use emerging organic contaminants (EOCs). Polycyclic and nitro-aromatic musks, bromobenzenes, dechlorane plus isomers (syn-DP, anti-DP) and methyl triclosan were frequently detected at appreciable levels (2-20,000pgL(-1)). The observed concentrations of the monitored contaminants in Singapore's marine environment were generally comparable to previously reported levels in other coastal marine systems. To our knowledge, these are the first measurements of these emerging contaminants of concern in Singapore or Southeast Asia. The developed method may prove beneficial for future environmental monitoring of hydrophobic organic contaminants in marine environments. Further, the study provides novel information regarding several potentially hazardous contaminants of concern in Singapore's marine environment, which will aid future risk assessment initiatives. Copyright © 2015 Elsevier B.V. All rights reserved.
    Science of The Total Environment 04/2015; 523:219-232. DOI:10.1016/j.scitotenv.2015.04.012 · 4.10 Impact Factor
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    • "Ricart et al. (2010) used a measure of photosynthetic efficiency to determine a NOEC for the algal community of 0.42 ␮g l −1 . Generally, algae are considered the most sensitive organisms to TCS (Dann and Hontela, 2011). Cyanobacteria, such as Anabaena flos-aquae, are also sensitive with a NOEC of 0.67 ␮g l −1 . "
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    ABSTRACT: Triclosan (TCS) is a ubiquitous antibacterial agent found in soaps, scrubs, and consumer products. There is limited information on hazardous effects of TCS in the environment. Here, rotating annular reactors were used to cultivate river biofilm communities exposed to 1.8 μg l−1 TCS with the timing and duration of exposure and recovery during development varied. Two major treatment regimens were employed: i) biofilm development for 2, 4 or 6 weeks prior to TCS exposure and ii) exposure of biofilms to TCS for 2, 4 or 6 weeks followed by recovery. Biofilms not exposed to TCS were used as a reference condition. Communities cultivated without and then exposed to TCS all exhibited reductions in algal biomass and significant (p < 0.05) reductions in cyanobacterial biomass. No significant effects were observed on bacterial biomass. CLSM imaging of biofilms at 8 weeks revealed unique endpoints in terms of community architecture. Community composition was altered by any exposure to TCS, as indicated by significant shifts in denaturing gradient gel electrophoresis fingerprints and exopolymer composition relative to the reference. Bacterial, algal and cyanobacterial components initially exposed to TCS were significantly different from those TCS-free at time zero. Pigment analyses suggested that significant changes in composition of algal and cyanobacterial populations occurred with TCS exposure. Bacterial thymidine incorporation rates were reduced by TCS exposure and carbon utilization spectra shifted in terms substrate metabolism. Direct counts of protozoans indicated that TCS was suppressive, whereas micrometazoan populations were, in some instances, stimulated. These results indicate that even a relatively brief exposure of a river biofilm community to relatively low levels of TCS alters both the trajectory and final community structure. Although some evidence of recovery was observed, removal of TCS did not result in a return to the unexposed reference condition.
    Aquatic toxicology (Amsterdam, Netherlands) 02/2015; 161C. DOI:10.1016/j.aquatox.2015.02.012 · 3.51 Impact Factor
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