Sunlight-induced degradation of fluoroquinolones in wastewater effluent: Photoproducts identification and toxicity

•The sunlight degradation of five fluoroquinolones was studied in WWTPs effluent.•The photodegradation was studied at environmentally significant concentrations.•Photoproducts were identified and their distribution profiles were monitored.•The toxicity of the photoproducts was studied by long-term V. fischeri assay.•Photoproducts contribution to the overall biotoxic effect (μgL−1 level) was proved.