Clinical management of field worker organophosphate poisoning.

A group of 16 cauliflower workers poisoned by residues of the organophosphate insecticides mevinphos and phosphamidon was followed in weekly clinics with interviews and determinations of plasma and erythrocyte cholinesterase levels. None had preexposure baseline values. Although six had initial erythrocyte cholinesterase values within the laboratory normal range, subsequent testing showed their erythrocyte activity had been significantly inhibited. While the most severe symptoms of the 16 subjects resolved after 28 days, their erythrocyte cholinesterase levels did not reach a plateau until an average of 66 days after exposure, after which most patients continued to report blurred vision, headache, weakness or anorexia. These findings support the view that the diagnostic utility of single cholinesterase levels is limited in the absence of baseline values.