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: 2.98). 05/2011; 31(4):285-311. DOI: 10.1002/jat.1660
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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- "Mass balance suggests that 30% of the TCS entering municipal wastewater treatment plants (WWTPs) was adsorbed to and persisted in the sludge, while 5% was still present in the effluent (Bester 2003). Due to its incomplete removal in the WWTPs, TCS can be introduced into the environment following the discharge of effluent and land application of biosolids (Dann and Hontela 2011;Al-Rajab et al., 2015). As a result, TCS is frequently detected at concentrations up to a few g/L in aquatic environments (Bedoux et al., 2012). "
ABSTRACT: Cyanobacteria can co-exist in eutrophic waters with chemicals or other substances derived from personal care products discharged in wastewater. In this work, we investigate the interactions between the antimicrobial agent triclosan (TCS) and the bloom-forming cyanobacteria Microcystis aeruginosa. Microcystis aeruginosa was very sensitive to TCS with the 96 h lowest observed effect concentration of 1.0 and 10 μg/L for inhibition of growth and photosynthetic activity, respectively. Exposure to TCS at environmentally relevant levels (0.1–2.0 μg/L) also affected the activities of superoxide dismutase (SOD) and the generation of reduced glutathione (GSH), while microcystin production was not affected. Transmission electron microscope (TEM) examination showed the destruction of M. aeruginosa cell ultrastructure during TCS exposure. TCS however, can be biotransformed by M. aeruginosa with methylation as a major biotransformation pathway. Furthermore, the presence of M. aeruginosa in solution promoted the photodegradation of TCS. Overall, our results demonstrate that M. aeruginosa plays an important role in the dissipation of TCS in aquatic environments but high residual TCS can exert toxic effects on M. aeruginosa.
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- "Since UVR (UV-B and UV-A) has a decisive role on the bacterial community structure of aquatic organisms, particularly in early stages of development, further investigations regarding this issue must be conducted. Triclosan (TCS), potassium dichromate (PD) and prochloraz (PCZ) are widely used in industry and agriculture practices (Barnhart, 1997; Dann and Hontela, 2011; Ohlsson et al., 2009) leading to their guaranteed appearance in the aquatic environment (Chalew and Halden, 2009; Mohan and Pittman, 2006). The effects of these chemicals in the aquatic organisms are well-documented (Domingues et al., 2013, 2010; Oliveira et al., 2009; Orvos et al., 2002; Prabakaran et al., 2006; Saglio et al., 2003). "
ABSTRACT: This study aimed to assess the effect of ultraviolet radiation (UVR) and chemical stress (triclosan-TCS; potassium dichromate-PD; prochloraz-PCZ) on bacterial communities of zebrafish (Danio rerio) embryos (ZEBC). Embryos were exposed to two UVR intensities and two chemical concentrations not causing mortality or any developmental effect (equivalent to the No-Observed-Effect Concentration-NOEC; NOEC diluted by 10-NOEC/10). Effects on ZEBC were evaluated using denaturing gradient gel electrophoresis (DGGE) and interpreted considering structure, richness and diversity. ZEBC were affected by both stressors even at concentrations/doses not affecting the host-organism (survival/development). Yet, some stress-tolerant bacterial groups were revealed. The structure of the ZEBC was always affected, mainly due to xenobiotic presence. Richness and diversity decreased after exposure to NOEC of PD. Interactive effects occurred for TCS and UVR. Aquatic microbiota imbalance might have repercussions for the host/aquatic system, particularly in a realistic scenario/climate change perspective therefore, future ecotoxicological models should consider xenobiotics interactions with UVR.
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- "The other interesting thing about triclosan is that like sodium fluoride, triclosan in toothpaste and other dental care products can reduce gum disease, especially in individuals that are prone to gum disease (Dann and Hontela 2011). Thus, for people that have a lot of gum problems, using toothpastes and other dental products that contain triclosan can have a definite benefit. "
DESCRIPTION: A summary of interesting information that is pertinent to the student assignment to evaluate contaminants in products in their own households.
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