Acute Oral Toxicity of Bentazon, Czechoslovak Developmental Herbicide, to Pheasants and Rabbits and Clinical Symptomatology of Poisoning

Veterinarni Medicina 38, 1993, 115-121

Adult rabbits of the New Zealand White breed and pheasants were used to determine the rate of acute oral toxicity (LD50), clinical symptomatology of poisoning of organisms loaded with lethal doses, and the recovery of intoxicated individuals from the toxic effects of bentazon, Czechoslovak developmental herbicide (Research Institute of Chemical Technology, Bratislava), administered at sublethal doses within the framework of obligatory toxicological testing of this herbicide. The determined acute oral toxicity (LD50) was 11 39 mg/kg in rabbits and 2918 mg/kg of live weight in pheasants. The table shows LD50 of the tested herbicide for various animal species. The LD50 values of bentazon produced abroad (Germany) are also shown for comparison in this table. If the LD50 values of both herbicides are compared, Czechoslovak developmental bentazon appears safer. The administration of lethal doses (1110 and 1170 mg/kg in rabbits, 2750 and 3100 mg/kg of live weight in pheasants) resulted in clinical symptoms of poisoning detected predominantly in the respiratory system. Shallow accelerated breathing and dyspnoea, CNS suppression, pronounced increase in body temperature, rapid onset and high intensity of rigor mortis were observed. Animals which died as a result of asphyxia induced by the sublethal doses (1000 mg/kg in rabbits and 2200 mg/kg in pheasants) were observed after 2 - 4 days, Difficult accelerated breathing and increased body temperature disappeared after 1 - 2 days while the remaining symptoms after 2 - 3 days. The loss of appetite persisted for 2 - 4 days. The results of the LD50 determinations of the tested herbicide indicate that it will not produce acute intoxications in pheasants and rabbits provided the recommended technology of herbicidal treatmens of crops (480 g per 100 m2) is observed. The above mentioned aspects as well as the findings that the given animal species tolerate this herbicide easily lead to a conclusion that it is safe for rabbits and pheasants. It may likely be safe for all gallinaceous birds and hares. It belongs to the low-toxic substances according to the WHO classification (1975)

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