IMMUNOLOGICAL CHANGES AMONG FARMERS EXPOSED TO PHENOXY HERBICIDES - PRELIMINARY-OBSERVATIONS

Objectives-To evaluate short term immunological changes after agricult ural exposure to commercial formulations of chlorophenoxy herbicides. Methods-Blood samples were collected hom 10 farmers within seven days before exposure, one to 12 days after exposure, and again 50 to 70 day s after exposure. Whole blood was used to count lymphocyte subsets wit h monoclonal antibodies. Peripheral blood mononuclear (PBM) cells were used to measure natural killer (NK) cell activity and lymphocyte resp onse to mitogenic stimulations. Values before exposure were used as re ference. Results-in comparison with concentrations before exposure, a significant reduction was found one to 12 days after exposure in the f ollowing variables (P <0.05): circulating helper (CD4) and suppressor T cells (CD8), CD8 dim, cytotoxic T lymphocytes (CTL), natural killer cells (NK), and CD8 cells expressing the surface antigens HLA-DR (CD8- DR), and lymphoproliferative response to mitogen stimulations. All imm unological values found 50-70 days after exposure were comparable with concentrations before exposure, but mitogenic proliferative responses of lymphocytes were still significantly decreased. Conclusions-Accord ing to our data agricultural exposure to commercial 2,4-dichlorophenox yacetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA) fo rmulations may exert short term immunosuppressive effects. Further stu dies should clarify whether the immunological changes found may have h ealth implications and can specifically contribute to cancer aetiology .