Sugar cane vinasse in water bodies: impact assessed by liver histopathology in tilapia.

Aquatic ecosystems are the main receptors of toxic substances from human activities. With the increase in sugar cane production, vinasse - the main residue of ethanol production - is a potential contaminant of water resources, due to its high organic matter content. This study was aimed at evaluating the toxicity of vinasse by examining the liver of the fish Oreochromis niloticus exposed to different dilutions of sugar cane vinasse (1%, 2%, 5%, 5% and 10%) in laboratory bioassays. Portions of liver were collected and fixed for histological and histochemical techniques to detect total proteins, polysaccharides and lipids. In the histological analysis, the groups treated with vinasse exhibited significant alterations, such as loss of cytoplasmic integrity, loss of cell limit and tissue disorganization. Protein and lipid profiles were not altered. Higher accumulation of polysaccharides was detected in fish exposed to lower concentrations of vinasse, with a gradual decrease in animals treated with vinasse in higher concentrations. We concluded that vinasse has a dose-dependent toxic and cytotoxic potential in water bodies and that the liver is strongly affected when acutely exposed to this contaminant.