Triclosan (TCS) is an antimicrobial agent used widely in household products such as soaps, household cleaners, cosmetics, sportswear, mouthwash and toothpaste. It is a bioaccumulative compound known for its high toxicity to algae, daphnids, fish and other aquatic organisms. We investigated its occurrence in effluents, biosolids and surface waters in Australia, as well as its fate in Australian soils and wastewater treatment plants (WWTPs), including the effects on microbial processes in soils. The concentrations of TCS in 19 effluents ranged from 23 to 434 ng/L (median 108 ng/L) and in 17 biosolids from 0.09 to 16.79 mg/kg on dry weight basis (median 2.32 mg/kg). TCS at concentrations of up to 75 ng/L were detected in receiving waters from five creeks affected by effluent discharge from WWTPs. The removal rate of TCS in five selected WWTPs ranged from 72 and 93%, ascribed mainly to sorption onto sludge and biological degradation. Biodegradation in a clay loam soil was noted with a half life of 18 days. However the half-lives under field conditions are expected to be very different. The studies on the effect of TCS on soil microbiological processes showed that triclosan can disrupt the nitrogen cyclein sensitive soils at concentrations ≥5 mg/kg. In view of the recent risk assessment by the Australian regulatory agency NICNAS, there is an urgent need to assess exposure to TCS and its effect on ecosystem health.
Keywords: antimicrobial agents, biocides, biosolids, environmental fate, nitrification, personal care products