Genotoxicity and immunotoxicity of wastewater effluents discharged from Vilnius Wastewater Treatment Plant.

The aim of the present study was to assess the genotoxicity, cytotoxicity and immunotoxicity potential of treated wastewater effluents (TWE) discharged from the Vilnius Wastewater Treatment Plant. The analysis of micronuclei, nuclear buds (genotoxicity endpoints), bi-nucleated and fragmentedapoptotic cells (cytotoxicity endpoints) in peripheral blood of rainbow trout (Oncorhynchus mykiss) after a 12- day exposure to TWE revealed a significant increase (p = 0.009) of micronuclei in exposed O. mykiss specimens compared to control fish. No formation of nuclear buds, bi-nucleated and fragmented- apoptotic cells was noted. The analysis of immunotoxicity demonstrated a significant decrease in the neutrophile percentage and an increase in the thrombocyte count in blood of the fish exposed to TWE. The physicochemical analysis of oil products (C14–C28), benzo(a)pyrene and heavy metals (Pb, Cd, Zn, Cu, Hg) in TWE showed that concentrations of xenobiotics satisfy criteria for effluents discharged into receiving waters. Suspended solid concentrations detected in certain samples of TWE were higher than their Maximum Permissible Concentration in effluents discharged into water receivers, while concentrations of oil products found in insoluble form of certain samples sometimes exceeded their Maximum Permissible Concentration in water basins.