Evaluation of immune parameters in propanil-exposed farm families

The rice herbicide propanil induces alterations in the mouse immune system, causing significant decreases in T cell-dependent and T cell-independent a ntibody responses. This postemergent herbicide is used extensively in rice production in the Mississippi River delta region of the southern United Sta tes. The aerial application and airborne drift of propanil may pose health concerns to exposed farm families living adjacent to sprayed rice fields. T o determine if aerial spraying of propanil increases risks of altered immun e responses in families bordering rice fields, immune parameters were asses sed during a 2-year study. Families living within 100 yards of rice fields were compared in a case control study to farm families whose homes exceeded 1 mile from any rice field. Blood was analyzed in adults (n = 56) and chil dren (n = 52) at three time intervals: (1) preseason, prior to propanil app lication; (2) 5-7 days after aerial application of propanil to rice fields; and (3) postseason, following harvest. Exposed adults and children were co mpared with controls for a number of immune parameters. Total cell count an d the percentage of various lymphocytes (T cells, B cells, CD4(+) helper ce lls, and CD8(+) suppressor cells) and natural killer (NK) cells, mitogen-in duced cell proliferation, cytokine (IL-2(+)) production, and NK cell functi on were assessed. A comparison of immune function between exposed and nonex posed farm families showed no significant differences, possibly related to propanil exposure. However, some immune test parameters changed as a functi on of season rather than propanil exposure. The data indicate that individu als living next to rice fields are not at increased risk of altered immune function due to propanil exposure.