findings with slow rate of recovery of brain AChE activity agree with a
previous study in which another OP (DFP) was injected to rats for 22 day. It
was observed in that study that plasma AChE activity had returned to a stable
100% of the control level by 5 to 6 day after last DFP dose while the recovery
of brain AChE activity after termination of DFP dosing was retarded. Brain
AChE activity was only about 65% of control at 28 day after last dose of DFP
(Gearhart et al., 1994). Additional data showing that AChE activity in brain
tissue is the most susceptible indicator of adverse toxic effect of dicrotophos
in animal studies also supports the assumption (Dicrotophos: Health-based
Reassessment of Administrative Occupational Exposure Limits, 2003).