Inhibition of esterase activity and an undercounting of circulating monocytes in a population of production workers.

A cross-sectional review of routine employee health status examinations has identified an undercounting of circulating monocytes associated with an inhibition of a surface monocyte esterase, alpha-naphthyl butyrate esterase. It is postulated that this inhibition is associated with an organophosphate used in the production process. Correlation with routine measures of health status are presented.

Industrial exposure to organophosphorus compounds. Studies of a group of workers with a decrease in esterase-staining monocytes.

When an automated counting instrument using an esterase stain was employed, decreased monocyte counts were observed in a group of process workers exposed to organophosphate esters. Their monocyte counts were not found to be depressed with manual counting or with an automated counter using another staining method. The apparent depression was transient. In these workers and a comparison group, theoretical adverse consequences of decreased monocyte esterase and also possible changes in other esterases were explored. No anergy was seen with mumps or staphylococcal phage lysate hypersensitivity skin tests. Histology of the mumps reaction was similar in both groups. The depressed monocyte counts were significantly associated with a mild reduction in erythrocyte cell acetylcholinesterase, but no reduction was seen in plasma pseudocholinesterase or lymphocyte neurotoxic esterase.