Hidden Cancer Risks of LA Wildfires

Image by Gwendolyn Salas / MJH Life Sciences using AI

I am heartbroken for my adopted city of Los Angeles, California. The past 7 days of wildfires have caused death, destruction, and a financial crisis we can only begin to imagine. The stress on the evacuees, first responders, and the city of Los Angeles is beyond measurement. As I thankfully watched a plane drop fire retardant on flames several miles from my home, I pondered the health of the firefighters working the line on the ground beneath the aircraft. With 50- to 70-mph winds, the orange fluid can quickly spread to unintended areas. I feel the fire and smoke particles, even with an N95 mask securely in place. How will these fires affect cancer rates and medical conditions for the first responders (police, emergency medical services, firefighters, utility workers) and people living in fire areas?

Wildfire smoke exposure is a growing public health concern. As we are sadly aware, significant wildfire events have increased in California and other states. The increase is due to climate change caused by multiple factors: lack of rain, increased aridity and storms, and outdated fire suppression strategies. These fires have caused more smoke days per year than in previous years. The increase in smoke days has promoted necessary research studying what pollutants are contained in wildfire smoke. Research on wildfire smoke has increased not just among firefighters but the public as well. Adetona et al state that wildfire smoke is linked to adverse cardiovascular, respiratory, dermatologic, and nervous system outcomes.¹ Korsiak et al reported that wildfire smoke in Canada caused metabolic effects linked to diabetes, and the smoke contains toxins that can lead to cancer.²

Alarmingly, wildfire smoke is especially detrimental to children, contributing to the development of asthma and an increase in asthma exacerbations. Children are especially vulnerable because they are growing and breathe more pollutants relative to their size. Recent reviews of wildfire smoke in children have found evidence of respiratory issues, mental health issues, and birth weight effects in those exposed to wildfire smoke, as well as some evidence of cardiac function issues.³ Effective risk communication regarding wildfire smoke is especially critical for these vulnerable populations. A reminder to all health care providers: as part of your patient education, include information about ash cleanup, which should be done on all outdoor equipment with “wet” cleaning, removing shoes before entering your house, and avoiding blowing the ash into your yards.⁴

We worry about our safety, but do we think about the women and men running toward the smoke and the burning carcinogens? In 2022, the International Agency for Research on Cancer noted that firefighting as an exposure should be classified as “carcinogenic to humans” due to current literature.⁵ According to the National Institutes of Health, firefighting is hazardous.⁶ It is associated with increased rates of certain screenable cancers such as prostate and melanoma. Daniels et al noted, in a study of 3 large fire departments in the US, that overall cancer incidence and mortality significantly increased by 9% and 14%, respectively, compared with the general population.⁷

So, what makes firefighters more susceptible to the formation of cancer after these exposures? According to Zhou et al, who studied the DNA methylation of peripheral blood samples from 45 incumbent and 41 newly recruited nonsmoking male firefighters, DNA methylation changes occurred.⁸ The changes in DNA are highly associated with the activation of cancer pathways and an increase in cancer formation. Zhou and colleagues noted that DNA methylation biomarkers have the potential to be used to identify the cumulative effect of exposures and to identify firefighters at increased risk of disease susceptibility. These markers could improve screening for firefighters and decrease the incidences of cancer in this vulnerable population. We must do more to keep these first responders safe and free from long-term health issues.

The past 2 weeks in the Los Angeles area have been terrifying, heartbreaking, and filled with stories of human spirit and connection. As nurses, we are constantly called upon during times of crisis to do our best work. Take the time to educate yourself on the dangers of wildfire smoke and ash so we can care for our families, neighbors, and friends. Stay safe and well.

References

1. Adetona O, Reinhardt TE, Domitrovich J, et al. Review of the health effects of wildland fire smoke on wildland firefighters and the public. Inhal Toxicol. 2016;28(3):95-139. doi:10.3109/08958378.2016.1145771
2. Korsiak J, Pinault L, Christidis T, Burnett RT, Abrahamowicz M, Weichenthal S. Long-term exposure to wildfires and cancer incidence in Canada: a population-based observational cohort study. Lancet Planet Health. 2022;6(5):e400-e409. doi:10.1016/S2542-5196(22)00067-5
3. Holm SM, Miller MD, Balmes JR. Health effects of wildfire smoke in children and public health tools: a narrative review. J Expo Sci Environ Epidemiol. 2021;31(1):1-20. doi:10.1038/s41370-020-00267-4
4. Wildfires. American Academy of Pediatrics. Updated October 22, 2024. Accessed January 29, 2025. https://www.aap.org/en/patient-care/disasters-and-children/disaster-management-resources-by-topic/wildfires/
5. Jahnke SA, Jitnarin N, Haddock CK, et al. Meta-analysis of incidence and mortality of firefighter cancer: an update on emerging science. Asian Pac J Cancer Prev. 2024;25(3):801-811. doi:10.31557/APJCP.2024.25.3.801
6. Lee DJ, Ahn S, McClure LA, et al. Cancer risk and mortality among firefighters: a meta-analytic review. Front Oncol. 2023;13:1130754. doi:10.3389/fonc.2023.1130754
7. Daniels RD, Bertke S, Dahm MM, et al. Exposure-response relationships for select cancer and non-cancer health outcomes in a cohort of U.S. firefighters from San Francisco, Chicago and Philadelphia (1950-2009). Occup Environ Med. 2015;72(10):699-706. doi:10.1136/oemed-2014-102671
8. Zhou J, Jenkins TG, Jung AM, et al. DNA methylation among firefighters. PLoS One. 2019;14(3):e0214282. doi:10.1371/journal.pone.0214282