Sex-Specific Effects\nof Environmental Exposure to\nthe Antimicrobial Agents Benzalkonium Chloride and Triclosan on the\nGut Microbiota and Health of Zebrafish (Danio rerio)

The use of disinfectants containing benzalkonium chloride\n(BAC)\nhas become increasingly widespread in response to triclosan (TCS)\nrestrictions and the COVID-19 pandemic, leading to the increasing\npresence of BAC in aquatic ecosystems. However, the potential environmental\nhealth impacts of BAC on fish remain poorly explored. In this study,\nwe show that BAC and TCS can induce the gut dysbiosis in zebrafish\n(Danio rerio), with substantial effects\non health. Breeding pairs of adult zebrafish were exposed to environmentally\nrelevant concentrations of BAC and TCS (0.4–40 μg/L)\nfor 42 days. Both BAC and TCS exposure perturbed the gut microbiota,\ntriggering the classical NF-κB signaling pathway and resulting\nin downstream pathological toxicity associated with inflammatory responses,\nhistological damage, inhibited ingestion, and decreased survival.\nThese effects were dose-dependent and sex-specific, as female zebrafish\nwere more susceptible than male zebrafish. Furthermore, we found that\nBAC induced toxicity to a greater extent than the restricted TCS at\nenvironmentally relevant concentrations, which is particularly concerning.\nOur results suggest that environmental exposure to antimicrobial chemicals\ncan have ecological consequences by perturbing the gut microbiota,\na previously underappreciated target of such chemicals. Rigorous ecological\nanalysis should be conducted before widely introducing replacement\nantimicrobial compounds into disinfecting products.