Background Firefighters have increased cancer incidence and mortality rates compared to the general population, and are exposed to multiple products of combustion including known and suspected carcinogens. Objective The study objective was to quantify fire response exposures by role and self-reported exposure risks. Methods Urinary hydroxylated metabolites of polycyclic aromatic hydrocarbons (PAH-OHs) were measured at baseline and 2–4 h after structural fires and post-fire surveys were collected. Results Baseline urine samples were collected from 242 firefighters. Of these, 141 responded to at least one of 15 structural fires and provided a post-fire urine. Compared with baseline measurements, the mean fold change of post-fire urinary PAH-OHs increased similarly across roles, including captains (2.05 (95% CI 1.59–2.65)), engineers (2.10 (95% CI 1.47–3.05)), firefighters (2.83 (95% CI 2.14–3.71)), and paramedics (1.84 (95% CI 1.33–2.60)). Interior responses, smoke odor on skin, and lack of recent laundering or changing of hoods were significantly associated with increased post-fire urinary PAH-OHs. Significance Ambient smoke from the fire represents an exposure hazard for all individuals on the fireground; engineers and paramedics in particular may not be aware of the extent of their exposure. Post-fire surveys identified specific risks associated with increased exposure.

Objective: Evaluate the effectiveness of firefighter exposure reduction interventions. Methods: Fireground interventions included use of self-contained breathing apparatus by engineers, entry team wash down, contaminated equipment isolation, and personnel showering and washing of gear upon return to station. Urinary polycyclic aromatic hydrocarbon metabolites (PAH-OHs) were measured after structural fire responses before and after intervention implementation. Separately, infrared sauna use following live-fire training was compared to standard postfire care in a randomized trial. Results: The fireground interventions significantly reduced mean total urinary postfire PAH-OHs in engineers (−40.4%, 95%CI −63.9%, −2.3%) and firefighters (−36.2%, 95%CI −56.7%, −6.0%) but not captains (−11.3% 95%CI −39.4%, 29.9%). Sauna treatment non-significantly reduced total mean PAH-OHs by −43.5% (95%CI −68.8%, 2.2%). Conclusions: The selected fireground interventions reduced urinary PAH-OHs in engineers and firefighters. Further evaluation of infrared sauna treatment is needed.

Firefighters are exposed to carcinogens and have elevated cancer rates. We hypothesized that occupational exposures in firefighters would lead to DNA methylation changes associated with activation of cancer pathways and increased cancer risk. To address this hypothesis, we collected peripheral blood samples from 45 incumbent and 41 new recruit non-smoking male firefighters and analyzed the samples for DNA methylation using an Illumina Methylation EPIC 850k chip. Adjusting for age and ethnicity, we performed: 1) genome-wide differential methylation analysis; 2) genome-wide prediction for firefighter status (incumbent or new recruit) and years of service; and 3) Ingenuity Pathway Analysis (IPA). Four CpGs, including three in the YIPF6, MPST, and PCED1B genes, demonstrated above 1.5-fold statistically significant differential methylation after Bonferroni correction. Genome-wide methylation predicted with high accuracy incumbent and new recruit status as well as years of service among incumbent firefighters. Using IPA, the top pathways with more than 5 gene members annotated from differentially methylated probes included Sirtuin signaling pathway, p53 signaling, and 5' AMP-activated protein kinase (AMPK) signaling. These DNA methylation findings suggest potential cellular mechanisms associated with increased cancer risk in firefighters.

Introduction Firefighters are exposed to carcinogens and have elevated cancer rates. Cancer may be caused by activation of oncogenes or inhibition of tumour suppressor genes, such as through alterations in microRNA (miRNA) concentrations and DNA methylation. We hypothesised that occupational exposures in firefighters would lead to epigenetic changes associated with activation of cancer pathways and increased cancer risk. We designed this study to compare epigenetic changes in incumbent firefighters and new recruits. Methods At the time of subject selection, the study population consisted of 119 incumbents and 70 recruits. From this group, 108 subjects were randomly selected for miRNA analysis and 96 for DNA methylation analysis, both evenly divided among incumbents and recruits. Only non-smoker male firefighters were included in the final comparison. MiRNAs and DNA methylation were measured with the nCounter Human v3 miRNA expression assay with over 828 miRNAs and the Illumina MethylationEPIC 850 k chips, respectively. Result After adjusting for age and BMI, miR-1260a, miR-145–5 p, miR-181c-5p, miR-331–3 p, miR-361–5 p, and miR584–3 p were significantly downregulated in incumbent firefighters. MiR-208b-5p, miR-30e-3p, and miR-486–3 p were significantly overexpressed in incumbents. Controlling the genome-wide false discovery rate at 5%, 22 CpGs were annotated to promoter regions of a gene and were hypermethylated in the incumbents including YIPF6, HELB, SYT5 and DVL2. Discussion MiR-181c-5p, miR-145–5 p, and miR-584–3 p are involved in tumour suppression. MiR-30e-3p is upregulated in skin cancer and is a poor prognostic factor in lung cancer. Co-amplification of the YIPF6 gene with the androgen receptor may stimulate prostate tumour progression. Aberrant activation of HELB reduces genomic stability, a hallmark of cancer. SYT may have a novel function in breast cancer. DVL2 is a part of the Wnt signalling pathway involved in multiple cancers. These epigenetic biomarkers of carcinogenic exposure in firefighters should be further evaluated in larger studies.

OBJECTIVES:Firefighters have elevated cancer incidence and mortality rates. MicroRNAs play prominent roles in carcinogenesis, but have not been previously evaluated in firefighters.METHODS:Blood from 52 incumbent and 45 new recruit nonsmoking firefighters was analyzed for microRNA expression, and the results adjusted for age, obesity, ethnicity, and multiple comparisons.RESULTS:Nine microRNAs were identified with at least a 1.5-fold significant difference between groups. All six microRNAs with decreased expression in incumbent firefighters have been reported to have tumor suppressor activity or are associated with cancer survival, and two of the three microRNAs with increased expression in incumbent firefighters have activities consistent with cancer promotion, with the remaining microRNA associated with neurological disease.CONCLUSION:Incumbent firefighters showed differential microRNA expression compared with new recruits, providing potential mechanisms for increased cancer risk in firefighters.