Triclosan (TCS) is a broad spectrum antibacterial agent present as an active ingredient in some personal care products such as soaps, toothpastes and sterilizers. It is an endocrine disrupting compound and its increasing presence in water resources as well as in biosolid-amended soils used in farming, its potential for bioaccumulation in fatty tissues and toxicity in aquatic organisms are a cause for concern to human and environmental health. TCS has also been detected in blood, breast milk, urine and nails of humans.
The significance of this is not precisely understood. Data on its bioaccumulation in humans are also lacking. Cell based studies however showed that TCS is a pro-oxidant and may be cytotoxic via a number of mechanisms. Uncoupling of oxidative phosphorylation appears to be prevailing as a toxicity mechanism though the compound’s role in apoptosis has been cited. TCS is not known to be carcinogenic per se in vitro but has been reported to promote tumourigenesis in the presence of a carcinogen, in mice. Recent laboratory reports appear to support the view that TCS oestrogenicity as well as its anti-oestrogenicity play significant role in cancer progression. Results from epidemiological studies on the effect of TCS on human health have implicated the compound as responsible for certain allergies and reproductive defects.
Its presence in chlorinated water also raises toxicity concern for humans as carcinogenic metabolites such as chlorophenols may be generated in the presence of the residual chlorine. In this paper, we carried out a detailed overview of TCS pollution and the implications for human and environmental health. Background Triclosan (TCS) is a broad-spectrum antimicrobial agent in some personal care products such as soap, sanitizer and skin cream (Kirk–Othmer; MacIsaac et al.; Perencevich et al.; Schweizer ). Its widespread use in homes and in health care centres may have explained its versatility as a water micro-pollutant (Helbing et al.; Kolpin et al.; Li et al.; Loraine and Pettigrove; Park and Yeo; Reiss et al. TCS has been mentioned (Foran et al. ) as an endocrine disruptor (ED), a group of compounds known to interfere with hormone functions (Wingspread Consensus Statement ).
Structurally, TCS molecule possesses functional groups for both phenol (5-chloro-2-(2,4-dichlorophenoxy) phenol) and ether (2,4,4-trichloro-2-hydroxydiphenyl ether) (Fig. ). Its lipophilicity (log K ow = 4.8 octanol–water partition coefficient) suggests bioaccumulation in fatty tissues which raises toxicity concern. Structure of triclosan (CAS 3380-34-5) The hormonal activity of TCS (Crofton et al.
) is widely acknowledged in vitro (Huang et al. ) and in vivo, in laboratory (Stoker et al.
) and aquatic (Ishibashi et al. ) animals which raises fear for human health.
Evidence of human toxicity is still a matter for debate in scientific circles, however some state authorities such as in Minnesota are considering a ban on all TCS-containing products (Dhillon et al. 
) or a restriction (TIME ), partly due to the reported TCS-resistant bacteria or ostensibly yielding to the pressure mounted by some professional bodies (APUA ) for the perceived adverse effects on health.
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Apart from its widely reported adverse effects on cellular metabolism, its ecotoxicity also raises fear of dwindling economic fortunes from water resources. The present work attempts to review available data on environmental impact as well as evidence suggestive of human toxicity and to suggest future research directions. The estimated acceptable daily intake for TCS is 0.17 nmol/kg/day (Blanset et al. ) and some drinking water levels of TCS have been found to be higher than this estimate (Table ). TCS after disposal, drains ultimately into underground (Sorensen et al. ) and to surface waters (Table ) where it may finally reach humans by drinking contaminated water or via the food chain such as consumption of animals and vegetation exposed to TCS (Park and Yeo ).
An annual discharge of 18 tonnes of TCS to the surface water in USA had been reported, with more than half this volume coming from wastewater treatment plants (WWTPs) (Halden and Paul ). Underground water from shallow wells and boreholes has been reported to contain up to 0.10 nM TCS (Sorensen et al. Concentrations of TCS in some untreated surface waters were reported to range from 7.9 to 39 nM (Kolpin et al.; Perez et al. High value of 297.7 nM was reported in the influents of certain wastewater treatment plants (Kumar et al. ) while effluents concentrations ranging from 0.41 to 3.5 nM were reported in treated wastewater effluents (Glassmeyer et al.; Snyder et al. Source Concentration (nM) References Surface water Natural streams/rivers nd–7.9 Ying et al. () 0.26 Halden and Paul () Streams with input of raw wastewater 5.5 Fair et al.