Toxicities of antifouling biocide Irgarol 1051 and its major degraded product to marine primary producers

Amy Q. Zhang, Kenneth M Y Leung, Wing Hin Kevin Patrick Kwok, Vivien W W Bao, Michael H W Lam

Research output: Journal article publicationJournal articleAcademic researchpeer-review

36 Citations (Scopus)


Irgarol 1051 (2-methythiol-4-tert-butylamino-6-cyclopropylamino-s-triazine) is an algaecide commonly used in antifouling paints. It undergoes photodegradation which yields M1 (2-methylthio-4-tert-butylamino-6-amino-s-triazine) as its major and most stable degradant. Elevated levels of both Irgarol and M1 have been detected in coastal waters worldwide; however, ecotoxicity effects of M1 to various marine autotrophs such as cyanobacteria are still largely unknown. This study firstly examined and compared the 96 h toxicities of Irgarol and M1 to the cyanobacterium Chroococcus minor and two marine diatom species, Skeletonema costatum and Thalassiosira pseudonana. Our results suggested that Irgarol was consistently more toxic to all of the three species than M1 (96 h EC50 values: C. minor, 7.71 μg L-1 Irgarol vs. >200 μg L-1 M1; S. costatum, 0.29 μg L-1 Irgarol vs. 11.32 μg L-1 M1; and T. pseudonana, 0.41 μg L-1 Irgarol vs. 16.50 μg L-1 M1). Secondly, we conducted a meta-analysis of currently available data on toxicities of Irgarol and M1 to both freshwater and marine primary producers based on species sensitivity distributions (SSDs). Interestingly, freshwater autotrophs are more sensitive to Irgarol than their marine counterparts. For marine autotrophs, microalgae are generally more sensitive to Irgarol than macroalgae and cyanobacteria. With very limited available data on M1 (i.e. five species), M1 might be less toxic than Irgarol; nonetheless this finding warrants further confirmation with additional data on other autotrophic species.
Original languageEnglish
Pages (from-to)575-586
Number of pages12
JournalMarine Pollution Bulletin
Issue number6-12
Publication statusPublished - 3 Mar 2008
Externally publishedYes


  • Biofouling
  • Degradation products
  • Marine primary producers
  • Water quality guidelines

ASJC Scopus subject areas

  • Aquatic Science
  • Oceanography
  • Pollution


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