Chromosome damage and cancer risk in the workplace: The example of cytogenetic surveillance in Croatia

The use of cytogenetic assays in the surveillance of populations occupationally exposed to genotoxic carcinogens originates from the assumption that chromosomal alterations might be causally involved in early stages of carcinogenesis. Historical cohort studies have since 1990s consistently reported an association between the level of chromosomal aberrations (CA) in peripheral lymphocytes of healthy subjects and the risk of cancer. Only in few cases, have these results been transformed into a regulatory tool for improving occupational safety. The cytogenetic surveillance program adopted for more than two decades in the Republic of Croatia is one of these few examples. Croatian workers exposed to genotoxic agents were systematically screened for CA, to identify occupational settings needing a priority intervention. Significant increases of mean CA frequency were observed in groups exposed to ionizing radiation, chemical agents, and mixed exposures when compared with a group of unexposed referents. CA data on 736 men and 584 women, monitored between 1987 and 2000, have been associated with cancer incidence. Although the small size of the cohort did not allow for reaching statistical significance, the medium tertile of the CA frequency distribution was associated with a doubling of cancer incidence rate ratio (IRR = 2.40; 95% CI 0.85-6.77) when compared with the lowest tertile. For chromosome-type CA, IRR was non-significantly increased for both the medium (IRR 1.53, 95% CI 0.58-3.99) and high categories (IRR 1.69; 95% CI 0.61-4.72). Recommendations for future strategies comprise the inclusion of predictive biomarkers in surveillance programs, the definition of a regulatory framework, and their possible use for the identification of individual risk profiles.