Date of Award

Spring 1995

Document Type



Life & Environmental Sciences

First Advisor

Marilyn Schendel

Second Advisor

John Christenson

Third Advisor

John Hawthorne


The use of pesticides, especially organophosphate pesticides, causes different adverse effects in human applicators. Most of the symptoms are due to inhibition of the enzyme cholinesterase. There are several methods that are used to determine these drops in cholinesterase levels. The Montana Department of Health and Environmental Sciences uses a modification of the Method of Michel that measures change in pH of human plasma samples to determine cholinesterase levels. During the 1994 season, two new quality control sections were added to ensure more accurate results and these proved to be helpful. However, this study suggests additional changes including the involvement of more applicators. The program, if run correctly, could protect the health of many Montana pesticide applicators.