Combined toxicological effects of pesticides: A fish multi-biomarker approach

• Fish exposed to insecticides combination showed a differential physiologic profile.
• Insecticides in combination provoked lipid oxidative damage in several tissues.
• The multi-biomarker approach was useful to assess the toxicity of pesticides in fish.
• The set of selected biomarkers was able to separate treatments.
• Pesticides in combination produced deleterious effects on fish health.

The combined effects of two synthetic insecticides on a wide array of biomarkers in the freshwater fish Piaractus mesopotamicus were studied. Fish were exposed to sublethal concentrations of endosulfan (ED), lambda-cyhalothrin (LC), and the combination of both pesticides for 96 h. The set of analyzed biomarkers included morphometric and hematological parameters, transaminases and alkaline phosphatase activities, antioxidant enzymes activities and oxidative damage biomarkers measured in gills, liver, kidney, brain and muscle. According to the principal component analysis, the most significant effects were produced by the ED–LC combination. So, the mixture of both insecticides produced an increase in the liver-somatic index, hematological changes related to immunological biomarkers (increased white blood cells count, and alterations in the differential leukocytes count), decreased liver transaminases activity, antioxidant enzymes induction in almost every tissue, and lipid peroxidation levels increases in liver, kidney and brain of exposed fish. Our results suggest deleterious effects of ED and LC insecticides in combination, and support the usefulness of the multi-biomarker approach for the characterization of toxicological mechanisms induced by pesticides.