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Comparative Toxicity of Emulsifiable Concentrate and Suspension Concentrate Formulations of 2′,5-Dichloro-4′-Nitrosalicylanilide Ethanolamine Salt

Open-File Report 2024-1037
By: , , , , and 
https://doi.org/10.3133/ofr20241037

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Abstract

The 2-aminoethanol salt of niclosamide (2′,5-dichloro-4′-nitrosalicylanilide) is a pesticide known as Bayluscide that is used in conjunction with TFM (4-nitro-3-[trifluoromethyl]phenol), also known as 3-trifluoromethyl-4-nitrophenol) to treat tributaries to the Great Lakes infested with invasive parasitic Petromyzon marinus (sea lamprey). Adding 0.5 to 2 percent Bayluscide with TFM can substantially reduce the amount of TFM required to achieve effective control. Currently, an emulsifiable concentrate (EC) formulation of Bayluscide is used in combination with TFM during some stream treatments completed by the Great Lakes Fishery Commission’s binational sea lamprey control program. The Bayluscide EC formulation is highly effective; however, it degrades application tubing, adheres to application equipment, and raises concerns for worker safety because of the solvent in the formulation, N-methyl-2-pyrrolidone.

We collaborated with a pesticide formulation company to develop a Bayluscide 20-percent suspension concentrate (SC) formulation as a potential replacement for the Bayluscide 20-percent EC formulation. The 20-percent SC formulation was specifically developed using inert ingredients approved for use by the U.S. Environmental Protection Agency and the Health Canada Pest Management Regulatory Agency. Although approved for use, the inclusion of a small quantity of an antimicrobial in the formulation warranted evaluating the toxicological profile to sea lamprey and select nontarget fish species. We evaluated and compared the toxicity of the 20-percent SC formulation to the 20-percent EC formulation using continuous-flow diluter systems and larval sea lamprey and select cold-, cool-, and warm-water fish as test animals. Our results demonstrate comparable toxicological profiles between the two formulations with the 20-percent SC formulation being slightly less toxic to the nontarget species evaluated.

Suggested Citation

Luoma, J.A., Schueller, J.R., Schloesser, N.A., Kirkeeng, C.A., and Wolfe, S.L., 2024, Comparative toxicity of emulsifiable concentrate and suspension concentrate formulations of 2′,5-dichloro-4′-nitrosalicylanilide ethanolamine salt: U.S. Geological Survey Open-File Report 2024–1037, 10 p., https://doi.org/10.3133/ofr20241037.

ISSN: 2331-1258 (online)

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Methods
  • Results
  • Discussion
  • Conclusion
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Comparative toxicity of emulsifiable concentrate and suspension concentrate formulations of 2′,5-dichloro-4′-nitrosalicylanilide ethanolamine salt
Series title Open-File Report
Series number 2024-1037
DOI 10.3133/ofr20241037
Year Published 2024
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Upper Midwest Environmental Sciences Center
Description Report: vii, 10 p.; Data Release
Online Only (Y/N) Y
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details