Abstract

One hundred and twenty-six patients poisoned by the organic phosphorus insecticide Metaisosystox were investigated. Hiccough and extrapyramidal manifestations were noticed in some patients. Serum cholinesterase levels showed an initial fall and then a rise above normal. The fall of cholinesterase was marked in patients who were exposed for relatively long periods but not in patients accidentally exposed for short times. The rise in serum cholinesterase is thought to be a compensatory protective mechanism.

Correlation between serum cholinesterase levels and symptomatology was absent in some patients but present in the majority. Cholinesterase inhibition may not be the only mechanism by which organic phosphorus compounds cause poisoning.