Comparative toxicities of 10 widely used biocides in three freshwater invertebrate species

ABSTRACT

Owing to their widespread use in wooden products, industrial products, cosmetics, and personal care products, biocides are frequently detected in wastewater and surface water. In this study, I examined the acute toxicities of 10 commonly used biocides, namely methylisothiazolinone, benzisothiazolinone, octylisothiazolinone, dichlorooctylisothiazolinone, iodopropynyl butylcarbamate, triclosan, azoxystrobin, pyraclostrobin, climbazole, and clotrimazole, in the water flea (Daphnia similis), freshwater planarians (Dugesia japonica) and green neon shrimp (Neocaridina denticulata). Among the 10 tested biocides, dichlorooctylisothiazolinone was the most toxic to both D. similis and N. denticulata, whereas pracolstrobin was the most toxic to Du. japonica. By contrast, the least toxic biocides for D. similis, Du. japonica, and N. denticulata were climbazole, iodopropynyl butylcarbamate, and methylisothiazolinone, respectively. The 48-h nominal LC₅₀ values of all the biocides, except for benzisothiazolinone and climbazole, in D. similis were mostly less than 1 mg/L. In addition, the 96-h nominal LC₅₀ values of all the biocides, except for methylisothiazolinone and iodopropynyl butylcarbamate, in Du. japonica was less than 1 mg/L. These results indicate the biocides with low LC₅₀ values are relatively toxic to freshwater organisms.

KEYWORDS:

• Aquatic toxicity
• emerging contaminant
• ecological risk
• isothiazolinone biocides
• strobilurin fungicide
• azole fungicide

Acknowledgement

The author would like to thank Mr Siang-Heng Wang his assistance on planarian toxicity assay and Ms Mei-Tzu Pan for her assistance on water flea, planarian, and shrimp toxicity assays.

Disclosure statement

No potential conflict of interest was reported by the author.

Notes on contributor

Dr. Mei-Hui Li is a professor of Department of Geography, National Taiwan University. Her academic interests include the aquatic toxicity of environmental pollutants and developing alternative aquatic animal models for monitoring environmental pollutants.

Additional information

Funding

This work was supported by Ministry of Science and Technology, Taiwan (MOST) under grants MOST 103-2313-B-002-028-MY3 and MOST 106-2313-B-002-010.