By Emily Kohanbash
Firefighters, who embody exceptional bravery and sacrifice, are responsible for ensuring the safety of their communities and confronting life-threatening situations. While they effectively secure our neighborhoods, the often-overlooked question arises: are these protectors adequately safeguarded themselves? Through a conversation with a firefighter, I learned some of the many risks associated with this heroic occupation. I then decided to do some research, only to discover that cancer is the leading cause of death in firefighters and not carbon monoxide poisoning, as I previously had thought. Indeed, firefighters not only face the immediate dangers of flames but also battle with hazards lingering in the aftermath. These risks include emotional, physical, and genotoxic challenges that negatively impact their well-being. While the profession exhibits a great feeling of purpose, firefighters encounter several dangerous genotoxic hazards when exposed to various harmful toxins. It’s crucial to understand these risks, especially concerning their health.
Despite their dedication, every year, 80,000 firefighters are injured, and tragically, 100 lose their lives, which calls for a closer examination of the hidden dangers they face. One might have assumed that the primary risk for firefighters lies in the physical dangers of being trapped in burning buildings. However, research uncovered a startling truth: cancer poses the most significant threat. This sparked my interest in learning more about the genotoxic hazards that firefighters face.
Understanding genotoxicity—the capacity of chemical agents to damage genetic material within cells, leading to mutations and the possible development of cancer—becomes crucial to understanding the health concerns that firefighters confront. Genotoxicity is often confused with mutagenicity; however, it is essential to clarify that, although all mutagens exhibit genotoxicity, not all genotoxic substances are mutagenic. When putting out fires and rescuing innocent civilians, firefighters are in contact with many dangerous genotoxic agents like formaldehyde, benzene, polycyclic aromatic hydrocarbons, and heavy metals. Numerous epidemiological studies consistently establish a positive correlation between firefighting and chronic diseases, with a significant emphasis on cancer, highlighting the negative influence of genotoxicity on these health outcomes. Furthermore, this correlation extends to specific types of cancer, such as prostate, skin melanoma, and testicular cancer, showing the impact on the overall health of firefighters.
Benzene, classified as a Group 1 carcinogen, is a well-established cause of leukemia in humans and is associated with chromosome abnormalities. A study was done in China to explore the repercussions of benzene exposure on the chromosomes of workers, particularly focusing on aneuploidy in lymphocytes. The researchers employed fluorescence in situ hybridization (FISH), to analyze both interphase and metaphase cells, from the peripheral blood of 43 workers exposed to benzene and 44 controls. FISH is a technique that utilizes fluorescent probes to bind to specific DNA sequences, enabling the visualization and quantification of specific chromosomal abnormalities. The study revealed that workers exposed to higher levels of benzene displayed an increase in the frequency of cells with one hybridization signal for chromosomes 7 and 8 when analyzed in metaphase spreads. This increase was more prominent in metaphase FISH compared to interphase FISH, suggesting that metaphase FISH is more sensitive in detecting aneuploidy in benzene-exposed lymphocytes. The findings emphasize the genotoxic potential of benzene exposure, especially given its Group 1 carcinogen status and its association with aneuploidy, highlighting the occupational risks firefighters face amongst other professions.
The composition of the air that firefighters are exposed to during training sessions at a fire facility was also studied. The goal was to understand the potential health risks associated with inhaling combustion products. The study specifically collected samples from the smoke generated during oil fires in the training facility. Through detailed analysis, the researchers identified various organic compounds in the smoke, including alkanes and polycyclic aromatic hydrocarbons. These are dangerous substances that can be released when materials burn. To assess the potential genetic impact of these compounds, the researchers employed the Ames microbial mutagenesis test. This test involves using particular bacterial strains to check if a substance can cause genetic mutations. The results indicated that the smoke from the training facility had mutagenic activity, meaning it could potentially lead to genetic changes. The Ames test highlighted an average mutagenic response, particularly on the bacterial strain TA98 when metabolic activation occurred. Essentially, the study not only identified the presence of various chemicals in the smoke but also demonstrated that the smoke could induce genetic mutations, showing the possible health implications for firefighters exposed to such training emissions.
An additional study utilized a comet assay to further understand how firefighters’ jobs affect their health. This assay utilizes single-cell gel electrophoresis to study cells on an individual level. A group of firefighters from eight fire stations were monitored, and their urine was checked to determine what substances were present. Monohydroxy-polycyclic aromatic hydrocarbons (OHPAHs), which come from fires, were found in their urine. They also checked for markers that show if there could be DNA damage. The results showed that the levels of OHPAHs in the urine of firefighters were much higher (up to 340%) than in a control group of people who didn’t fight fires. They found that specific carcinogenic OHPAHs had the most significant increases, like 1-hydroxy naphthalene and 1-hydroxy acenaphthene. Additionally, the scientists found that the markers for oxidative stress, which can harm cells, were higher in non-smoking firefighters compared to the group that didn’t fight fires. They concluded that these increased abnormalities were connected to firefighters’ line of work.
DNA methylation patterns among firefighters show potential links between occupational exposures, genotoxicity, and cancer risk. Blood samples from 45 incumbent and 41 newly recruited non-smoking male firefighters were analyzed, revealing four CpGs, including those in the YIPF6, MPST, and PCED1B genes, with significant differential methylation. Genome-wide methylation accurately predicted incumbent and new recruit status, as well as years of service among incumbent firefighters. It was seen that incumbent firefighters had more methylation than the new firefighters. Ingenuity Pathway Analysis (IPA) identified vital pathways associated with differentially methylated probes, such as Sirtuin signaling, p53 signaling, and AMP-activated protein kinase (AMPK) signaling. These findings suggest that changes in DNA methylation may represent potential molecular mechanisms linking occupational exposures to genotoxicity and increased cancer risk in firefighters. The identified pathways are known to play roles in cellular processes relevant to genotoxic stress, highlighting the importance of understanding epigenetic alterations in addressing the heightened cancer rates observed in this occupational group.
Heavy metals pose a direct link to cancer and genotoxic effects associated with chronic occupational exposure. A research study conducted in Thailand studied the genotoxic impacts caused by prolonged occupational exposure to heavy metals, such as lead (Pb), copper (Cu), zinc (Zn), and tin (Sn). Given the potential link between such exposure and mutations leading to cancer, the research aimed to show the genotoxic impact of these metal mixtures. The cytokinesis-blocked micronucleus (CBMN) assay in peripheral blood lymphocytes was employed, allowing the study of DNA damage through the measurement of tumor-associated protein levels and 8-hydroxy-2′-deoxyguanosine (8-OHdG) assay, a marker of oxidative stress-induced toxicity. The study involved 110 workers exposed to heavy metal mixtures and 105 controls. Results showed significant differences in blood Pb, Sn, and Cu levels between exposed workers and controls. The analysis of micronuclei in peripheral blood lymphocytes displayed an increased frequency in exposed workers, indicating genotoxic effects. Additionally, non-smoking exposed workers exhibited elevated levels of plasma 8-OHdG, suggesting increased oxidative stress. Firefighters with chronic exposure to heavy metals pose an elevated health risk due to DNA damage, potentially contributing to an increased risk of cancer, emphasizing the importance of monitoring genotoxic effects using assays like CBMN and 8-OHdG formation.
Data shows that more male than female firefighters work in America. This may explain why most studies on firefighters focus on male firefighters rather than female ones. However, research on females is also crucial, as the results may differ in ways, such as genotoxic concerns with reproductivity. A study was done that looked at whether certain chemicals called per- and polyfluoroalkyl substances (PFAS) could be linked to miscarriages in pregnant women. The results showed that higher levels of two specific PFAS, called PFOA and PFHpS, were associated with an increased risk of miscarriage. PFAs are found in PAHs as well as in fire extinguishers. Thus, it can be concluded that there is a genotoxic correlation between female firefighters and miscarriages.
Elements associated with genotoxic fire smoke are also linked to male infertility. A study was done to investigate male firefighters’ ability to have children. Twenty firefighters participated in a study where their fertility was checked through an online survey and semen analysis. The results showed that the semen, the fluid that carries sperm, of the firefighters was not as good as what is considered normal for fertility. Younger firefighters—under 45 years old—had more issues with their semen (42% had problems) compared to non-firefighters. The study also found that higher-ranking firefighters and those with better hygiene had better semen quality. However, firefighters who were exposed to fires more often had lower-quality semen, affecting things like sperm count and how the sperm looked. This study suggests that being a firefighter and being exposed to harmful environments might be linked to problems with fertility for men.
The health of first responders, including firefighters, exposed to the dust, gasses, and other carcinogenic substances present in the smoke from the World Trade Center (WTC) during the 9/11 attacks was investigated. Research showed that a higher percentage of these firefighters developed something called clonal hematopoiesis (CH) compared to firefighters who were not at the WTC. CH involves blood cells acquiring mutations, and it’s known to be connected to factors like smoking and exposure to substances that can damage genes, which are genotoxic agents. The researchers examined the DNA in the blood of these responders and found that 10% of those who were at the WTC had CH, while only 6.7% of those who weren’t there had it. The mutations they found mostly affected specific genes linked to CH; these genetic changes are considered genotoxic. To understand why this happens, they tested cells exposed to the dust from the WTC, and they found that it messed up the way the cells’ DNA copied itself, indicating genotoxic effects. The study also involved testing on mice treated with WTC dust. It was found that these mice had more genetic mutations in certain blood cells. Thus, the research suggests that being at the WTC during the attacks might have increased the risk of these first responders developing genotoxic mutations in their blood cells.
Genotoxic impacts on firefighters show a complex relationship between their work environment and well-being. While firefighters, portraying courage, face the immediate dangers of fires, the research highlights the often-overlooked risks linked to exposure to harmful substances like polycyclic aromatic hydrocarbons (PAHs) and per- and polyfluoroalkyl substances (PFAS). These substances, commonly found in fire emissions and firefighting activities, can pose potential threats to the reproductive health of both male and female firefighters. Studies on male firefighters raise concerns about semen quality and fertility, stressing the importance of protective measures and hygiene practices. Studies on female firefighters highlight the connection between PFAS exposure and the risk of miscarriage, broadening the considerations related to genetic damage. Advanced assays, such as the comet assay and the Ames microbial mutagenesis assay, provide insight into the genetic impacts of firefighting exposures. This furthers our understanding of the genotoxic risks firefighters face, emphasizing the need for comprehensive strategies to protect their well-being, given the challenges, especially cancer, they encounter in their profession.