GENETIC MONITORING OF MALATHION-EXPOSED AGRICULTURAL-WORKERS

The aerial application of malathion over large urban populations in So uthern California during the early 1990s raised concerns about adverse health effects, including the potential to cause genetic damage. Work ers in the Mediterranean fruit fly eradication program, which involved application of malathion as ground treatment, were studied to examine micronucleus formation and mutation frequencies assessed by the glyco phorin A (GPA) assay. In the 1992 pilot project the mean micronuclei l evel appeared higher in lymphocytes of exposed workers (n = 13) compar ed to controls (n = 4) (20.1 +/- 7.1 vs 14.3 +/- 7.2 respectively, P = 0.09). During the 1993 season, neither of the cohorts examined showed a higher level of micronuclei in workers exposed to malathion compare d to unexposed, nor did the pooled total (n = 53; means = 17.8 +/- 7.2 vs 18.5 +/- 6.3, respectively), even after adjustment by multiple reg ression. The GPA variant frequency was not associated with malathion e xposure in any of the cohorts. These results suggest that any potentia l risk of genotoxic damage from exposure to malathion is relatively lo w, but other assays may be more sensitive, and the sample size was sma ll. (C) 1998 Wiley-Liss, Inc.