Bioconcentration and Acute Intoxication of Brazilian Freshwater Fishes by the Methyl Parathion Organophosphate Pesticide

Figure 4

Cholinesterase activity in tissues of pacu, piavussu, and curimbatá exposed to 5 ppm methyl parathion. Each one of eight animals by species was individually treated with Folidol 600 for the indicated time in a 40 L aquarium. After 30 min of exposure blood was collected from four fishes by species and these fishes were submitted to euthanasia. Then, of the remaining fish, four pacus and four piavussus were euthanized after 78 h exposure, while four curimbatás were collected immediately after they showed no movement of opercula (from 3 to 5 h of exposure). Tissues were dissected and homogenized. Cholinesterase was assayed in serum and homogenates with acetylthiocholine and expressed as percentage of the activity found in controls.