Objectives To evaluate respiratory related mortality among underground coal miners after 37 years of follow-up. Methods Underlying cause of death for 9033 underground coal miners from 31 US mines enrolled between 1969 and 1971 was evaluated with life table analysis. Cox proportional hazards models were fitted to evaluate the exposure-response relationships between cumulative exposure to coal mine dust and respirable silica and mortality from pneumoconiosis, chronic obstructive pulmonary disease (COPD) and lung cancer. Results Excess mortality was observed for pneumoconiosis (SMR=79.70, 95% CI 72.1 to 87.67), COPD (SMR=1.11, 95% CI 0.99 to 1.24) and lung cancer (SMR=1.08; 95% CI 1.00 to 1.18). Coal mine dust exposure increased risk for mortality from pneumoconiosis and COPD. Mortality from COPD was significantly elevated among ever smokers and former smokers (HR=1.84, 95% CI 1.05 to 3.22; HR_K=1.52, 95% CI 0.98 to 2.34, respectively) but not current smokers (HR=0.99, 95% CI 0.76 to 1.28). Respirable silica was positively associated with mortality from pneumoconiosis (HR=1.33, 95% CI 0.94 to 1.33) and COPD (HR=1.04, 95% CI 0.96 to 1.52) in models controlling for coal mine dust. We saw a significant relationship between coal mine dust exposure and lung cancer mortality (HR=1.70; 95% CI 1.02 to 2.83) but not with respirable silica (HR=1.05; 95% CI 0.90 to 1.23). In the most recent follow-up period (2000–2007) both exposures were positively associated with lung cancer mortality, coal mine dust significantly so. Conclusions Our findings support previous studies showing that exposure to coal mine dust and respirable silica leads to increased mortality from malignant and non-malignant respiratory diseases even in the absence of smoking.

We performed a meta-analysis of epidemiological results for the association between occupational exposure as a firefighter and cancer as part of the broader evidence synthesis work of the IARC Monographs program. A systematic literature search was conducted to identify cohort studies of firefighters followed for cancer incidence and mortality. Studies were evaluated for the influence of key biases on results. Random-effects meta-analysis models were used to estimate the association between ever-employment and duration of employment as a firefighter and risk of 12 selected cancers. The impact of bias was explored in sensitivity analyses. Among the 16 included cancer incidence studies, the estimated meta-rate ratio, 95% confidence interval (CI), and heterogeneity statistic (I²) for ever-employment as a career firefighter compared mostly to general populations were 1.58 (1.14–2.20, 8%) for mesothelioma, 1.16 (1.08–1.26, 0%) for bladder cancer, 1.21 (1.12–1.32, 81%) for prostate cancer, 1.37 (1.03–1.82, 56%) for testicular cancer, 1.19 (1.07–1.32, 37%) for colon cancer, 1.36 (1.15–1.62, 83%) for melanoma, 1.12 (1.01–1.25, 0%) for non-Hodgkin lymphoma, 1.28 (1.02–1.61, 40%) for thyroid cancer, and 1.09 (0.92–1.29, 55%) for kidney cancer. Ever-employment as a firefighter was not positively associated with lung, nervous system, or stomach cancer. Results for mesothelioma and bladder cancer exhibited low heterogeneity and were largely robust across sensitivity analyses. There is epidemiological evidence to support a causal relationship between occupational exposure as a firefighter and certain cancers. Challenges persist in the body of evidence related to the quality of exposure assessment, confounding, and medical surveillance bias.

Background: Per-and polyfluoroalkyl substances (PFAS), are ubiquitous pollutants associated with adverse health outcomes. High PFAS levels have been demonstrated among career firefighters; less is known about PFAS levels among volunteer firefighters who comprise two-thirds of US firefighters. Methods: Volunteer fire department members completed a survey and provided blood samples. We calculated geometric means and 95% CIs for PFAS reported by the National Health and Nutrition Examination Survey (NHANES). We compared PFAS distribution and levels among non-Hispanic white adult male study participants to those in the 2015–2016 and 2017–2018 NHANES cycles. We assessed associations between PFAS serum levels and years of firefighting controlling demographics and occupation using linear regression. Results: Participant’s average age was 46.6 years (sd. 17.1). Perfluorododecanoic acid (PFDoA) was detected in almost half study but <3% of NHANES participants; serum levels of PFDoA, perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA) were elevated among participants compared with NHANES. Serum levels of both PFDA and PFDoA were positively associated with years of firefighting. Conclusions: Volunteer firefighters may have a different serum profile and levels of PFAS than the general population. Future work in this area should include volunteer firefighters from other geographic locations and assess sources of PFAS exposure.

Chronic disruption of circadian rhythms by night shift work is associated with an increased breast cancer risk. However, little is known about the impact of night shift on peripheral circadian genes (CGs) and circadian‐controlled genes (CCGs) associated with breast cancer. Hence, we assessed central clock markers (melatonin and cortisol) in plasma, and peripheral CGs ( PER1 , PER2 , PER3 , and BMAL1 ) and CCGs ( ESR1 and ESR2 ) in peripheral blood mononuclear cells (PBMCs). In day shift nurses ( n = 12), 24‐h rhythms of cortisol and melatonin were aligned with day shift‐oriented light/dark schedules. The mRNA expression of PER2 , PER3 , BMAL1 , and ESR2 showed 24‐h rhythms with peak values in the morning. In contrast, night shift nurses ( n = 10) lost 24‐h rhythmicity of cortisol with a suppressed morning surge but retained normal rhythmic patterns of melatonin, leading to misalignment between cortisol and melatonin. Moreover, night shift nurses showed disruption of rhythmic expressions of PER2 , PER3 , BMAL1 , and ESR2 genes, resulting in an impaired inverse correlation between PER2 and BMAL1 compared to day shift nurses. The observed trends of disrupted circadian markers were recapitulated in additional day ( n = 20) and night ( n = 19) shift nurses by measurement at early night and midnight time points. Taken together, this study demonstrated the misalignment of cortisol and melatonin, associated disruption of PER2 and ESR2 circadian expressions, and internal misalignment in peripheral circadian network in night shift nurses. Morning plasma cortisol and PER2 , BMAL1 , and ESR2 expressions in PBMCs may therefore be useful biomarkers of circadian disruption in shift workers.

The occupation of firefighting is classified as a Group 1 carcinogen. Increased cancer risk among firefighters may be partly attributable to increased occupational exposure to a range of chemicals, including per- and polyfluoroalkyl substances (PFAS). Some PFAS are known and suspect human carcinogens. Investigating epigenetic response to these PFAS exposures in firefighters may help to identify biological pathways of specific cancers, and previously unidentified health outcomes that are associated with PFAS. We therefore investigated the associations of serum PFAS concentrations with miRNA expression in firefighters. Serum samples collected from 303 firefighters from 6 sites across the USA were analyzed for 9 PFAS along with miRNA expression. Covariate-adjusted linear regression was used to estimate associations between log PFAS and miRNA expression, with false discovery rate (FDR) set to 0.05 for significance, and an exploratory cutoff of FDR q < 0.20. Gene set enrichment analysis (GSEA) was performed using miRTarBase's miRWalk pathways. Age, race-ethnicity, BMI, fire department, and sex were controlled for in all models. At FDR<0.05, the linear isomer of perfluorooctane sulfonic acid (PFOS) was inversely associated with miR-128-1-5p expression (Beta = -0.146, 95 % CI -0.216, -0.076). At a relaxed FDR of 0.20, we observed inverse associations for the sum of branched isomers of PFOS (Sm-PFOS) with 5 miRNAs (let-7d-5p, let-7a-5p, miR-423-5p, let-7b-5p, miR-629-5p). Several pathways were enriched for multiple PFAS, including those correlated with certain cancers, blood diseases, thyroid disorders, autoimmune disorders, and neurological outcomes. Some PFAS in firefighters were found to be associated with alteration of miRNA consistent with increased risk for a range of chronic diseases.