Radiometric assay of red cell and plasma cholinesterase in pesticide appliers from Minnesota.

In this study we demonstrate the uses of radiometric assay to detect anticholinesterases in a human population (N = 80) exposed to a broad spectrum of pesticides. The assay is nondilutional. Therefore, anticholinesterase (AChE) agents with low binding affinity can be detected. Our initial results show statistically significant exposure-related decreases in either red cell (AChE) or plasma cholinesterase activity ((butyrl)cholinesterase; BuChE) occurred not only among pesticide appliers who use organophosphates, but also among appliers of the fumigant phosphine. These data extend earlier observations made in laboratory animals exposed to this fumigant. Significant exposure-related decreases in AChE activity were seen in herbicide appliers and appear to be associated with exposure to the herbicide 2-methoxy-3,6-dichlorobenzoic acid. There was no evidence of exposure-related decreases in BuChE activity in herbicide appliers. Our in vivo data, coupled with preliminary in vitro studies of phosphine (50% AChE inhibition, 10 ppm) and 2-methoxy-3,6-chlorobenzoic acid (50% AChE and BuChE inhibition, 70 ppm), suggest that the radiometric assay may be used to detect a broader spectrum of biologically active anticholinesterase agents.