Combined effects of antibiotics and pesticides on zebrafish (Danio rerio): Enrofloxacin modulates the toxicity, tissue-specific bioconcentration and depuration of triazole fungicides.

The co-occurrence of pesticides and antibiotics is ubiquitous in aquatic environments. And co-existence of antibiotics maybe expands the environmental harm of pesticide pollution. Therefore, we report the investigation of the effect of enrofloxacin on toxicity and tissue accumulation and depurating triazole fungicides in zebrafish. Acute toxicity tests showed that enrofloxacin-tricyclazole and enrofloxacin-imazalil mixtures exhibited antagonistic response to zebrafish, while enrofloxacin-triadimefon exhibited synergistic response to zebrafish. Over 192 h exposure, the uptake rates (and elimination rates of three triazole fungicides in zebrafish tissues ranged from 1.79-55.9 L/kg*d and 0.278-0.995 d-1 in the single-exposure group, 1.69-54.4 L/kg*d and 0.439-1.101 d-1 in the co-exposure group, respectively. The presence of enrofloxacin prolonged the clearance time and enhanced the persistence of triadimefon in zebrafish, while it promoted the clearance of tricyclazole and imazalil. Muscle accumulated the largest portion of pesticides, accounting for 37. 9%-57.2 % of the total pesticide accumulation, while the head (20. 9%-36.8%) and viscera (21.9%-25.3%) contained smaller fractions. The exposure enrofloxacin affected bioconcentration factor values significantly, but didn't change pesticides relative compositions in zebrafish tissues. A tissue-specific shift occurred in tricyclazole and triadimefon bioconcentration in the presence of enrofloxacin, characterized by increased levels in the muscle tissues and decreased levels in the head and viscera. And co-exposure with enrofloxacin increased the total body burden of triadimefon, facilitating its accumulation in zebrafish but reducing the bioconcentration potential of imazalil and tricyclazole. Thus, the environmental scenario analysis demonstrated that ignoring complexation might misclassify environmental risks of pesticides.