Triclosan: environmental exposure, toxicity and mechanisms of action

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.

Systematic review of the literature on triclosan and health outcomes in humans

“…Consider the general concern that TCS may act as an endocrine disruptor capable of altering sex hormone function (Dann and Hontela 2011). As the concept of "endocrine disruption" may have multiple possible manifestations, an important next step in the assessment of evidence from human studies is to formulate one or more specific hypotheses.…”

Assessing triclosan-induced ecological and trans-generational effects in natural phytoplankton communities: a trait-based field method

“…The mode of toxic action of TCS in algae is not fully understood (Franz et al 2008;Dann and Hontela 2011). TCS can inhibit lipid synthesis destabilising cell membranes, but significant differences in sensitivity can be found among phytoplankton species (Franz et al 2008;Dann and Hontela 2011).…”

“…TCS can inhibit lipid synthesis destabilising cell membranes, but significant differences in sensitivity can be found among phytoplankton species (Franz et al 2008;Dann and Hontela 2011). This involvement of membrane homeostasis in toxicity points towards sensitivity being driven by size related traits, and surface/volume ratio.…”

Investigation on the montmorillonite adsorption of biocidal compounds incorporating thermodynamical-based multicomponent adsorption isotherm

“…Although wastewater treatment plant has reduced much of those compounds, there are a number of biocides in the scale of ng/L to mg/L that still remaining [2][3]. Some researchers denote that sublethal concentration of remaining biocides found in the nature, particularly in the reclaimed water, may accumulate in the microbial cells and elicit microbial resistance on the biocides itself and some antibiotics, which may impact on the human health [4][5][6].…”