Histopathological Effects of Roundup, a Glyphosate Herbicide, on Nile tilapia (Oreochromis niloticus)

The acute toxicity of Roundup, a glyphosate herbicide, to Nile tilapia, Oreochromis niloticus, was investigated with emphasis on histopathological effects. The values of 24-h, 48-h, 72-h and 96-h LC50 for young tilapia were 17.5, 17.1, 16.9 and 16.8 ppm, respectively, and those for adult tilapia were 46.9, 44.4, 40.0 and 36.8 ppm, respectively. They indicated that adult fish were more tolerant to Roundup than the much smaller young fish. Roundup concentration corresponding to the 96-h LC50 value for adult tilapia was used to study the effects of Roundup exposure in inducing histopathological changes of gills, liver and kidneys. In the gills, filament cell proliferation, lamellar cell hyperplasia, lamellar fusion, epithelial lifting and aneurysm were observed. In the liver, there was vacuolation of hepatocytes and nuclear pyknosis. Kidney lesions consisted of dilation of Bowman’s space and accumulation of hyaline droplets in the tubular epithelial cells. These changes occurred predominantly in the 96-h exposure.