Background: Certain chromium compounds are prominent metal carcinogens in both occupational and environmental settings. Objectives: The present study aimed to determine cytogenetic changes in the form of sister chromatid exchanges (SCEs) and predict chromium carcinogenicity in steel foundry workers; moreover, study the relationships between SCEs and tumor marker (CA 15-3) with the urinary chromium levels in the same group. Subjects and methods: The study included three groups; 20 apparently healthy male steel foundry workers, from different work sections, 20 apparently healthy male workers not exposed to chromium compounds, as a negative control group, and 10 lung cancer male patients from the National Cancer Institute, as a positive control group. All participants were interviewed using a pre-constructed questionnaire. Furthermore, they were subjected to urinary chromium level estimation,cytogentic study in the form of SCEs, and tumor marker (CA15-3) level measurement.Results: Steel workers had significantly higher levels of urinary chromium (5.5 ± 1.01 ٥g/L) compared to the other two groups (0.7 ± 0.19 and 0.8 ± 0.22 ٥g/L)
(P<0.001). Also, steel workers had significantly higher SCEs and CA15-3 levels compared to the negative controls (non-exposed workers) (P<0.001), but significantlyexperimenlower than those of the positive controls (lung cancer patients) (P<0.01). Moreover in the studied steel workers, there were significant positive correlations between urinary chromium levels and both SCEs and CA15-3 levels. Conclusion: It could be concluded that, unprotected occupational exposure to chromium in steel production industry can carry the risk of developing cytogenetic changes and cancer. These effects can be predicted by estimation of SCEs and tumor marker (CA 15-3) levels. Recommendations: Periodic medical examinations and biological monitoring of steel foundry workers, along with improving working conditions are ommended.