Toxicity of the antimicrobial compound triclosan and formation of the metabolite methyl-triclosan in estuarine systems

• Published in: Environmental toxicology 2008-04, Vol.23 (2), p.224-232
• Main Authors: DeLorenzo, M.E, Keller, J.M, Arthur, C.D, Finnegan, M.C, Harper, H.E, Winder, V.L, Zdankiewicz, D.L
• Format: Article
• Language: English
• Subjects: Aliivibrio fischeri - drug effects; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Anti-Infective Agents - analysis; Anti-Infective Agents - metabolism; Anti-Infective Agents - toxicity; Applied ecology; bacteria; bioaccumulation; Biological and medical sciences; Brackish water ecosystems; Ecotoxicology, biological effects of pollution; Environmental Monitoring; Fundamental and applied biological sciences. Psychology; General aspects; Lethal Dose 50; marine; methyl-triclosan; monitoring; Palaemonidae - drug effects; phytoplankton; Phytoplankton - drug effects; sediment; shrimp; South Carolina; Synecology; toxicity; triclosan; Triclosan - analogs & derivatives; Triclosan - analysis; Triclosan - metabolism; Triclosan - toxicity; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - metabolism; Water Pollutants, Chemical - toxicity
• ISSN: 1520-4081; 1522-7278
• DOI: 10.1002/tox.20327

Triclosan, a commonly used antimicrobial compound, has been measured in aquatic systems worldwide. This study exposed marine species to triclosan to examine effects primarily on survival and to investigate the formation of the degradation product, methyl-triclosan, in the estuarine environment. Acute toxicity was assessed using the bacterium Vibrio fischeri, the phytoplankton species Dunaliella tertiolecta, and three life stages of the grass shrimp Palaemonetes pugio. P. pugio larvae were more sensitive to triclosan than adult shrimp or embryos. Acute aqueous toxicity values (96 h LC₅₀) were 305 μg/L for adult shrimp, 154 μg/L for larvae, and 651 μg/L for embryos. The presence of sediment decreased triclosan toxicity in adult shrimp (24 h LC₅₀s were 620 μg/L with sediment, and 482 μg/L without sediment). The bacterium was more sensitive to triclosan than the grass shrimp, with a 15 min aqueous IC₅₀ value of 53 μg/L and a 15 min spiked sediment IC₅₀ value of 616 μg/kg. The phytoplankton species was the most sensitive species tested, with a 96 h EC₅₀ value of 3.55 μg/L. Adult grass shrimp were found to accumulate methyl-triclosan after a 14-day exposure to 100 μg/L triclosan, indicating formation of this metabolite in a seawater environment and its potential to bioaccumulate in higher organisms. Triclosan was detected in limited surface water sampling of Charleston Harbor, SC at a maximum concentration of 0.001 μg/L, substantially lower than the determined toxicity values. These findings suggest triclosan poses low acute toxicity risk to estuarine organisms; however, the potential for chronic, sublethal, and metabolite effects should be investigated.