Toxic effects of combined exposure to carbamazepine and triclosan on adult zebrafish (Danio rerio): Insights into acute mortality, neurotransmitters, biochemical response, and histopathology

As two representative pharmaceuticals and personal care products (PCPPs), carbamazepine (CBZ) and triclosan (TCS) are frequently detected in aquatic ecosystems worldwide, but their toxicological interactions remain unclear. This work evaluated the combined toxicity of CBZ and TCS to zebrafish (Danio rerio) in terms of acute mortality, biochemical response, and histopathology. The results showed that the 96-h acute toxicity interaction of CBZ and TCS fitted well to the concentration addition (CA) model, suggesting an additive effect. Compared with exposure to either CBZ or TCS alone, co-exposure to CBZ and TCS at equivalent toxic concentrations can lead to a profound increase in gamma-aminobutyric acid (GABA) and a reduction in acetylcholine (ACh) and acetylcholinesterase (AChE) levels. Compared with CBZ or TCS alone, the 21-day co-exposure to CBZ and TCS at the 2 % LC₅₀ aggravated oxidative stress and histopathological damage to the gills, brain, and liver. Overall, these findings provide a reference for the rational and complete assessment of the combined toxicity of the PPCPs to aquatic organisms.