Use of Comet Assay and Micronucleus test as noninvasive biomarkers in workers occupationally exposed to TiO2

Introduction: Numerous in vitro studies showed that TiO2 can induce oxidative and genotoxic responses, however the role of TiO2 on humans is controversial. The IARC classified it as suspected carcinogen (2B). The aim of the study was to investigate genotoxic and oxidative damage in workers employed in pigment production using non-invasive approach. Materials and Methods: Health status, life habits and occupational history of 30workers and 10 external control subjectswere recorded with a questionnaire. Airborne inhalable and respirable fraction of TiO2 were quantified with personal and area monitoring. Urinary Titanium was used to determine the subjects exposure. Genotoxic and oxidative damage (Comet AssayFPG and Micronucleus test) were assessed on salivary leukocytes and epithelial buccal cells. Results: Despite the low concentration of respirable dust, TiO2 was detected in filters for airborne dust collection in the paint producing area. TiO2 exposed subjects revealed in salivary leukocytes DNA damage (p<0.05) and oxidative stress (p<0.001) higher than controls, while no significant difference between groups of micronuclei counts were observed. In all population investigated the DNA damage and oxidative stress resulted significantly related to urinary Titanium and smoking habits (p<0.05), while task seniority was significantly related to oxidative stress (p<0.01). Conclusion: The Comet assay in salivary leukocytes proved a useful tool to evaluate early DNA and oxidative damage in workers occupationally exposed to TiO2 even at low exposure. These preliminary results need further investigation in a broader scale study.