Comparative Aquatic Toxicity Evaluation of 2-(Thiocyanomethylthio) Benzothiazole and Selected Degradation Products Using Ceriodaphnia Dubia
2-(Thiocyanomethylthio)benzothiazole (TCMTB) is a biocide used in the leather, pulp and paper, and water-treatment industries. TCMTB may enter aquatic ecosystems during its manufacture and use. TCMTB is environmentally unstable; therefore, it is important to evaluate the toxicity of the more persistent degradation products. This study compared the toxicity of TCMTB with its degradation products 2-mercaptobenzothiazole (2-MBT), 2-(methylthio) benzothiazole (MTBT), benzothiazole (BT), and 2-hydroxybenzothiazole (HOBT). Toxicity was determined using Ceriodaphnia dubia 48-hour acute and 7-day chronic test protocols. TCMTB was the most toxic compound evaluated in both the acute and chronic tests with EC50s of 15.3 and 9.64 μg/L, respectively. 2-MBT, the first degradation product, was the second most toxic compound with acute and chronic EC50s of 4.19 and 1.25 mg/L, respectively. The toxicity of MTBT and HOBT were similar with acute EC50s of 12.7 and 15.1 mg/L and chronic EC50s of 6.36 and 8.31 mg/L, respectively. The least toxic compound was BT with acute and chronic EC50s of 24.6 and 54.9 mg/L, respectively. TCMTB was orders of magnitude more toxic than its degradation products. Toxicity data on these benzothiazole degradation products is important because of concerns regarding their release, degradation, persistence, and non-target organism effects in aquatic ecosystems.
Nawrocki, S. T.; Drake, K. D.; Watson, C. F.; Foster, G. D.; and Maier, K. J.. 2005. Comparative Aquatic Toxicity Evaluation of 2-(Thiocyanomethylthio) Benzothiazole and Selected Degradation Products Using Ceriodaphnia Dubia. Archives of Environmental Contamination and Toxicology. Vol.48(3). 344-350. https://doi.org/10.1007/s00244-004-0105-1 PMID: 15750776 ISSN: 0090-4341