Toxicological assessment of thiobencarb and dithiopyr on Nile tilapia.

摘要

Thiiobencarb and dithiopyr are used as weed killers in rice fields where tilapia are cultured. Leaching into soil and thus water, also occurs. Nile tilapias were exposed acutely and chronically to thiobencarb and dithiopyr as single and mixed treatments. The LC₅₀ was 720 micro gl-1 and 280 micro gl-1 for thiobencarb and dithiopyr, respectively. High tissue concentrations were found in liver but low values in brain. Elevated serum and muscle total protein and alkaline phosphatase were observed during acute and chronic exposure. Apoptotic bands in the spleen, kidney and liver with micronuclei suggested alteration of cell division in gills exposed acutely or chronically to polluted water. Long-term exposure to the combined herbicides produced severe degenerative changes in the parenchymatous organs, wide spread necrosis and activation of melanocytes.