Evaluation of coumaphos exposure among tick eradication workers

Objective: To evaluate both the cholinesterase monitoring program and newer field methods of determining coumaphos exposure among tick eradication workers. Methods: Measured blood cholinesterase by the Ellman and field testing methods and tested urine for chlorferon pre- and postshift; conducted personal air sampling, patch sampling of clothing, and wipe sampling of hands for coumaphos. Results: Fifteen workers had normal plasma cholinesterase and acetylcholinesterase levels. No significant changes occurred pre- to postshift. High correlation was found between plasma cholinesterase and acetylcholinesterase levels by field testing and Ellman methods (r = 0.91, P < 0.01 and r = 0.63, P < 0.01, respectively). Chlorferon levels rose 4 to 6 hours after use (P < 0.01). Airborne coumaphos was detected in only one sample, in a trace amount. The majority of patch and hand wipe samples detected coumaphos. Conclusions: Dermal exposure to coumaphos resulted in significant increases in urinary metabolites of coumaphos.