Muna H. I. Al-Zubaidy, Yaareb J. Mousa, Mohammad M. Hasan, and Fouad K. Mohammad
الملخص العربي
Formulation components of organophosphate insecticidal preparations might affect their toxic action in
animals. The objective of this study was to examine and compare the acute toxicity and cholinesterase
inhibition in seven to 14-day-old chicks dosed orally with dichlorvos and diazinon in standard veterinary
and agricultural formulations. The acute (24 h) oral median lethal doses (LD50) of the formulations were
determined using the up-and-down method. Respective LD50 of dichlorvos of the veterinary and agricultural
formulations in chicks were 11.1 mg kg-1 and 6.51 mg kg-1 and those of diazinon 6.4 mg kg-1 and 6.7 mg kg-1.
Plasma and brain cholinesterase activities were measured by electrometry after in vivo and in vitro exposure
to organophosphates. The chicks showed signs of cholinergic toxicosis within one hour of dosing. Dichlorvos
(8 mg kg-1) and diazinon (4 mg kg-1) in the veterinary and agricultural formulation signifi cantly reduced
both plasma and brain cholinesterase activities in the chicks. The veterinary formulation of dichlorvos
reduced plasma ChE by 60 % and agricultural by 40 % and brain ChE by 93 % and 87 %, respectively. In
contrast, ChE inhibition by diazinon in the agricultural formulation of diazinon was stronger than by the
veterinary formulation; 72 % vs. 64 % in plasma and 97 % vs. 80 % in the brain, respectively. The highest
in vitro inhibitions were observed with dichlorvos in the agricultural formulation (50 %) in the brain
samples and with diazinon in the agricultural formulation (52 %) in the plasma samples. While they exist,
differences between formulations cannot be taken as a rule and further investigations should inventory the
toxicity of standard veterinary and agricultural organophosphate formulations in addition to the known
data for pure forms.
يعرب جعفر موسى | Yaareb Jaafar Mousa | 5569