firefighters

Job exposures may raise AF risk for firefighters

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Firefighters who reported responding to at least 31 fires per year were more than twice as likely to have a diagnosis of atrial fibrillation compared with those who responded to five or fewer fires per year, survey data show.

Exposure to inhaled smoke, pollutants, volatile organic compounds and polycyclic aromatic hydrocarbons in the firefighting environment has been associated with detrimental respiratory and CV effects, making firefighters a unique population with personal and occupational risk factors for CVD, Paari Dominic, MD, associate professor of medicine and molecular and cellular physiology and director of clinical cardiac electrophysiology at Ochsner-Louisiana State University Health Shreveport, and colleagues wrote in the Journal of the American Heart Association.

Graphical depiction of source quote presented in the article
Paari Dominic, MD, associate professor of medicine and molecular and cellular physiology and director of clinical cardiac electrophysiology at Ochsner-Louisiana State University Health Shreveport.

“Firefighters may be a unique, high-risk population with regards to developing atrial fibrillation at a younger age based on the number of fires they fight per year,” Dominic told Healio. “The assessment of the risk for AF in an individual patient may have to extend beyond traditional risk factors, especially among firefighters, and will have to include occupational risks. For example, palpitations, a common symptom of AF, should be approached differently in a firefighter aged at least 60 years who has fought 30 to 40 fires per year, with other traditional risk factors like hypertension and sleep apnea compared with similarly aged non-firefighter with the same symptoms and same risk factors.”

Survey data

In a cross-sectional study, Dominic and colleagues analyzed survey data from 10,860 active firefighters, of whom 93.5% were men and 95.5% were aged 60 years or younger. Firefighters who were members of at least one of five preselected professional organizations were surveyed via electronic links distributed by the organizations. The survey queried the number of fires fought per year as a measure of occupational exposure, as well as self-reported CVD. Respondents completed the surveys from October 2018 to December 2019.

Within the cohort, 89% identified as career (paid) firefighters, with 15.4% reporting prior military experience and 77.3% serving at the local level. Self-reported CVD included AF (2.7%), MI (1.7%), CAD (4.2%), peripheral artery disease (0.5%) and stroke (0.8%). Researchers found that firefighters who fought a higher number of fires per year had a higher prevalence of AF.

Among respondents, 4.5% of those who fought at last 31 fires per year had AF, compared with 3% of those who fought between 21 and 30 fires per year, 2.7% of those who fought 11 to 20 fires per year, 2.3% of those who fought six to 10 fires per year and 2% of those who fought fewer than five fires per year (P < .001).

Link between fires fought, incident AF

In regression analyses, researchers found the number of fires fought per year was associated with increased risk for AF (OR = 1.14; 95% CI, 1.04-1.25; P = .006).

Researchers also found that prevalence of AF increased with age, with firefighters aged at least 61 years reporting a higher incidence vs. those aged 60 years or younger (8.2% vs. 2.5%; P < .001). Governmental level of employment, type of employment (career, volunteer or paid per call) and presence of prior military service had no effect on the prevalence of AF.

“The results of this study need to be validated with a prospective cohort and more rigorous cardiac rhythm monitoring,” Dominic told Healio. “Second, the pathophysiology of this heightened risk needs to be further explored, specifically the role of particulate matter exposure and adrenergic stress. Another avenue for research is the optimal treatment of AF in firefighters considering their occupational lifestyle and hazards, such as the use of anticoagulation in firefighters who are at high risk of physical injuries.”

As Healio previously reported, CVD events are the leading cause of duty-related events in the fire service. Research published in July in Obesity showed firefighters who have a higher BMI and are older are more likely to have a higher prevalence of CVD risk factors.

9/11 Responders More Likely to Carry Genetic Mutations Tied to Cancer

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Clonal hematopoiesis seen in 10% of firefighters, medical personnel on the scene after WTC attack

A photo of New York City Firefighters and first responders surveying the rubble of the World Trade Center on 9/11/2001.

Firefighters and emergency medical personnel who were among the first to respond to the World Trade Center (WTC) attack on Sept. 11, 2001 harbor significantly higher rates of genetic mutations associated with blood cancers and other inflammatory diseases, researchers have found.

A full 10% of WTC responders exposed to particulate matter from the burning twin towers had evidence of clonal hematopoiesis (CH) on deep targeting sequencing, as compared with 6.7% of non-WTC-exposed firefighters, reported Amit Verma, MBBS, of Albert Einstein College of Medicine in New York City, and colleagues.

The difference amounted to a threefold higher likelihood of CH among the WTC responders after controlling for age, sex, and race/ethnicity (OR 3.14, 95% CI 1.64-6.03, P=0.0006), according to the findings in Nature Medicine.

The data “demonstrate that environmental exposure to the WTC disaster site is associated with a higher burden of CH, exceeding that expected in normal aging, and establish a rationale for mutational testing of the larger WTC-exposed population,” the group wrote.

“These blood mutations are not only associated with an increased risk of blood cancers, but also associated with increased risk of heart disease, lung disease, and other inflammatory diseases,” Verma told MedPage Today in an email. “Finding these mutations can lead to preventive measures such as heart checkups, controlling cholesterol, checkups for early signs of cancer — the best way to cure cancer is to catch it early.”

“These findings suggest that sequencing tests can be used for not just firefighters, but also police force, EMT workers, and others affected by the WTC exposure,” Verma added.

In a previous study, investigators demonstrated that WTC exposure among first responders was associated with an increased risk of monoclonal gammopathy of unknown significance — a precursor of multiple myeloma. This suggests that “sufficient time has now elapsed after exposure for the manifestation of other premalignant conditions,” wrote Verma and Colleagues.

In their current study, the authors collected blood samples from 481 deidentified WTC-exposed New York City firefighters (n=429) and WTC-exposed emergency medical personnel (n=52) from 2013 to 2015. These samples were assessed for DNA isolation and sequencing. Control peripheral blood samples were obtained from 255 firefighters from the Nashville, Tennessee area who had comparable baseline demographics.

In the WTC-exposed group of responders, the authors identified 48 individuals with 57 CH-associated mutations, compared with 17 individuals in the non-WTC-exposed firefighter cohort.

The association between WTC exposure and CH on multivariate analyses were maintained when the researchers removed the WTC-exposed emergency medical personnel and only compared the exposed to non-exposed firefighters (OR 2.93, 95% CI 1.52-5.65, P=0.0014).

It was also maintained when they restricting the analysis to those whose smoking status was available (smoking status was not linked with CH):

  • All exposed responders: OR 3.05 (95% CI 1.54-6.06, P=0.0015)
  • Exposed firefighters: OR 2.78 (95% CI 1.39-5.59, P=0.004)

The frequency of somatic mutations in WTC-exposed first responders showed an age-related increase, and predominantly affected the DNMT3A (16 of 57) and TET2 (7 of 57) genes.

In order to determine the effects of WTC particulate matter exposure on hematopoietic stem cells in vivo, Verma and colleagues administered wild-type mice with doses of WTC particulate matter considered to be equivalent to the exposure experienced by first responders. They observed a significant expansion of hematopoietic stem cells in the treated mice 30 days after exposures, with no significant change in other populations.