Sister chromatid exchange (SCE) and chromosomal aberrations were investigated in lymphocytes of 60 male papaya workers exposed to ethylene-dibromide (106934) (EDB) during post harvest fruit fumigation. Breathing zone samples were collected for periods ranging from 15 minutes to 8 hours in the papaya packing facilities. Seven cultures were established for each person: four for the aberration study and three for the SCE study. Results were compared to those from a group of unexposed male sugar mill workers. The average age, ethnic group, caffeine consumption, and alcohol consumption did not differ significantly between groups. More exposed men smoked tobacco, but more of the unexposed smoked marijuana. Exposures for an 8 hour day were generally at or slightly above the NIOSH recommended concentration of 45 parts per billion and far below the current OSHA standard of 20 parts per million. Mean SCE among EDB exposed and unexposed workers, stratified by current cigarette smoking status, showed no differences between exposed and unexposed workers. When marijuana smokers were excluded these results were essentially unchanged. An analysis of variance using dichotomized variables for exposures, marijuana smoking, and cigarette smoking, showed EDB exposure was again not significant in predicting SCE while both cigarette smoking and marijuana smoking were significant. Workers exposed more than 5 years did not have significantly different SCE exchange rates than nonexposed workers. Chromosome aberration analysis showed no significant differences between EDB exposed and unexposed workers in any category except chromatid type exchanges, the least frequent of the aberrations examined, which were seen in eight exposed and one unexposed individual. The authors conclude that EDB exposure at these low concentrations has no cytogenetic effect.