Estimating a worker entry interval for the carbamate pesticide furadan 4F insecticide.

Existing methods for the calculation of worker entry intervals by the use of kinetic data have focused on the anticholinesteratic organic phosphates. As carbamate pesticides share with these materials a common site for inhibition, the kinetic method was applied in estimating an entry interval for the carbamate, carbofuran, applied to citrus and grapes as Furadan 4F. No allowance was made for the more transient carbamylation of cholinesterase attributed to N-methyl carbamates, compared with the phosphorylation of the enzyme by organic phosphates. Thus, a measure of safety was built into the calculations which can then be used to establish safe reentry intervals to insure residue levels below the physiological threshold for cholinesterase inhibition.