Sublethal and environmentally relevant concentrations of triclosan and triclocarban induce histological, genotoxic, and embryotoxic effects in Clarias gariepinus (Burchell, 1822)

Antimicrobial additives in personal care products (PCPs) such as triclosan (TCS) and triclocarban (TCC) are of environmental concern due to their potential toxicity in non-target aquatic organisms. In this study, the histological, genotoxic (micronucleus assay), and embryotoxic effects of sublethal and environmentally relevant concentrations of TCS and TCC were evaluated in Clarias gariepinus (the African sharptooth catfish) over a period of 28 days. The 96 hLC(50) values of TCS and TCC against fingerlings of C. gariepinus were 16.04 mg/L and 41.57 mg/L respectively. The 24 hLC(50) and 26 hEC(50) (non-hatching) values for C. gariepinus embryos were 16.48 mg/L and 11.08 mg/L for TCS and 46.08 mg/L and 41.93 mg/L for TCC respectively. TCS was x3 to x4 more toxic to C. gariepinus fingerlings and embryos than TCC. Gill histological alterations ranged from mild to severe lamellar necrosis in the exposed fishes with Gill Alteration Index (GAI) of 1.60 on day 14 and 3.20 on day 28. There were significant dose-dependent increases (p < 0.05) in micronuclei and binucleated cells in the erythrocytes of exposed fishes compared to control. Embryotoxic effects assessed from 0 to 72 h post fertilization showed significant decreases (p < 0.05) in hatching success and number of heartbeats per minute, and significant increase (p < 0.05) in percentage abnormalities in the exposed embryos compared to control. The study demonstrates the need for regulatory measures and monitoring of the use of TCS and TCC in PCPs in order to mitigate potential adverse effects to non-target aquatic organisms. This will support the United Nations Sustainable Development Goal 14 on sustaining life below water.

Automated summary

This study evaluated the toxic effects of TCS and TCC on Clarias gariepinus, demonstrating that TCS was 3-4 times more toxic than TCC to fingerlings and embryos. Histological changes in gills, increased micronuclei and binucleated cells in erythrocytes, and decreased hatching success and heartbeat frequency were observed in exposed fishes and embryos. Regulatory measures and monitoring of these antimicrobial additives in personal care products are needed to protect non-target aquatic organisms and support UN Sustainable Development Goal 14.