A preliminary study of immunologic and hematologic profiles of peripheral blood from Nebraska farmers who apply pesticides to their fields.

OBJECTIVE: Laboratory studies have documented a wide range of pesticide-induced changes in the hematopoietic and lymphoreticular systems. Some of these are expressed as altered serum values, blood cell counts, and leucocyte functions. The goal of the present study was to determine whether these alterations were evident in peripheral blood of Nebraska farmers who applied pesticides to their fields.
METHODS: An invitation to participate was mailed to 100 residents (70 farmers; 30 controls) of Butler County, Nebraska. All respondents (51 farmers and 21 controls) were enrolled and surveyed by written questionnaire for health status and pesticide use. Our analysis included 45 farmers and 18 controls. The farmers were divided into a high (n = 23) and a low (n = 22) pesticide use group. Statistical correlations of ten blood values with both pesticide use and age were evaluated, since pesticide use correlated with age.
RESULTS: Four of the ten blood values correlated with pesticide use and age (Spearman Rho). In a multiple regression model, pesticide use (not age) proved to be a predictor of red blood cell count and hematocrit. In the same model, pesticide use was not a predictor of mean red cell volume or candida antigen-induced T-lymphocyte proliferation. Serum complement activity did not correlate with pesticide use among the farmers (n = 45) but was significantly reduced (ANOVA) in the high pesticide use group, compared to controls.
CONCLUSIONS: A preliminary study of blood values in a small cohort of Nebraska farmers found no pesticide-associated effects on 1) leucocyte count, 2) antigen- and mitogen-stimulated T-cell proliferation, 3) mitogen-stimulated B-cell proliferation, and 4) concentrations of serum IgG and IgM. The study found small but statistically significant pesticide-associated effects on red blood cells and serum complement.