Workers exposed to environmental pollutants at a waste disposal site were studied for genotoxic effects with cytogenetic tests and the comet (alkaline single-cell gel) assay. Analyses were performed on peripheral blood samples of 44 workers at a waste disposal site (DM) and 47 subjects of a control group (VE) matched for gender, age, and smoking habits. Chromosomal aberrations were evaluated in 1,000 lymphocytes per individual, sister chromatid exchanges in 50 cells, and DNA migration (tail moment) was determined in 100 leukocytes. Structural chromosome aberrations were more frequent in DM than in VE, but only the frequency of acentric fragments and the percentage of aberrant cells (excluding gaps) was significantly increased. No significant difference was found for the mean frequency of SCE. A statistically significant difference was also seen with the comet assay. The mean tail moment was higher in DM than in VE. However, no correlation was found between cytogenetic data and the effects in the comet assay. The results of our study indicate that DNA effects in the comet assay represent an independent endpoint which might be useful for the biomonitoring of genotoxic effects in addition to established tests.