Genotoxic damage and microRNA dysregulation in firefighters. An integrated biomonitoring case study

Firefighters are potentially exposed to multiple harmful substances, and their activities are classified as carcinogenic to humans. This case study assessed early genotoxic damage (fpg-comet and BMCyt assays) and epigenetic alterations (seven circulating miRNAs) in 35 firefighters compared to 45 non-exposed workers. Occupational exposure to fire smoke was self-reported via questionnaire. Firefighters showed higher median genotoxic DNA damage with respect to the non-exposed group (%DNA tail Buff 19.4 vs. 16.8; %DNA tail Enz 22.2 vs. 19.3; Tail moment 5.5 vs. 4.5; % of apoptotic cells 1.13 vs. 0.97). miRNAs related to air pollution, oxidative stress, tumor suppression, and immune responses, like mir-16, mir-15a, mir-29a, mir-125b, and mir-142, showed significant downregulation (p < 0.001) in the exposed group. Mean percentages of early apoptosis biomarkers and composite DNA damage indices among FF also differed significantly from the other participants (‰Condensed chromatin 0.46 vs. 0.06;‰Tot anomalies 5.15 vs. 3.82). Multiple correlations emerged, particularly between miRNAs and comet assay parameters, and between comet assay and BMCyt indicators. The implemented integrated approach provides information about the existence of a relationship between genotoxic and epigenetic effects in firefighters, also influenced by time since exposure. Future studies with bigger sample sizes are required.