Terrestrial ecotoxicological effects of the antimicrobial agent triclosan

Triclosan is an antimicrobial agent widely used in many contemporary consumer and health care products. This study assayed phytotoxicity of triclosan using plant growth tests, soil microbial activity using soil respiration and phosphatase activity tests and soil microbial functional diversity using the Biolog ECO plates. The results showed that triclosan inhibited plant growth in soil, with rice seeds being more sensitive than cucumber seeds with EC50 values of 57 and 108 mg/kg. Soil respiration was significantly inhibited in the treatments with triclosan at concentrations more than 10 mg/kg (dry soil) during the first 4 days of incubation, but recovered later on after longer incubation. Phosphatase activity was also inhibited for all the soils treated with triclosan (from 0.1 to 50 mg/kg dry soil), but a declining inhibition was observed after 2 days of incubation. Biolog analysis found that triclosan treatment increased the utilization of carbon sources and exerted no adverse effects on the functional diversity of soil microbial community.