{"id":2139,"date":"2025-09-17T12:28:44","date_gmt":"2025-09-17T19:28:44","guid":{"rendered":"https:\/\/blogs.ufv.ca\/chasi\/?p=2139"},"modified":"2025-09-17T12:28:44","modified_gmt":"2025-09-17T19:28:44","slug":"wildland-firefighters-and-polycyclic-aromatic-hydrocarbon-pah-exposure-biomonitoring-health-risks-and-industrial-disease-implications","status":"publish","type":"post","link":"https:\/\/blogs.ufv.ca\/chasi\/2025\/09\/17\/wildland-firefighters-and-polycyclic-aromatic-hydrocarbon-pah-exposure-biomonitoring-health-risks-and-industrial-disease-implications\/","title":{"rendered":"Wildland Firefighters and Polycyclic Aromatic Hydrocarbon (PAH) Exposure: Biomonitoring, Health Risks, and Industrial Disease Implications"},"content":{"rendered":"

CHASI is proud to maintain a longstanding partnership with the National Indigenous Fire Safety Council<\/a> (NIFSC). The NIFSC supports Indigenous communities in the development of their internal capacity to enhance community safety and resiliency. <\/em>As part of this partnership, CHASI is pleased to amplify their articles on our blog.<\/em><\/p>\n

CHASI\u2019s collaboration with the NIFSC, and many of their other research work, can be found on our NIFSC Publications page<\/a>. For questions about the NIFSC and their work, please visit their <\/em>contact page.<\/em><\/a><\/p>\n

Wildland Firefighters and Polycyclic Aromatic Hydrocarbon<\/strong> (PAH) Exposure: Biomonitoring, Health Risks, and Industrial Disease Implications<\/strong><\/h2>\n

A Critical Review of PAH Risks and Biomonitoring<\/h3>\n

By Len Garis and Mandy Desautels<\/em><\/p>\n

Wildland firefighting is a physically demanding and high-risk profession. While the immediate dangers\u2014heat, terrain, fatigue\u2014are well known, emerging research is drawing attention to another concern: exposure to toxic compounds in wildfire smoke. A recent systematic review published in Critical Reviews in Toxicology<\/em> (Silva et al., 2025) synthesizes findings from 16 studies conducted between 2019 and 2025, highlighting the occupational health implications of polycyclic aromatic hydrocarbons (PAHs) for wildland firefighters.<\/p>\n

This article summarizes the key findings and recommendations from that review, with a focus on Canadian firefighting contexts.<\/p>\n

PAHs are a group of chemicals formed during the incomplete combustion of organic material. They are present in wildfire smoke and are known to have carcinogenic and DNA mutagenic properties (IARC, 2010; Abdel-Shafy & Mansour, 2016). These compounds can enter the body through inhalation, ingestion, and dermal or skin absorption.<\/p>\n

In 2022, the International Agency for Research on Cancer (IARC) classified firefighting as a Group 1 carcinogenic occupation (Demers et al., 2022), citing cumulative exposure to substances like PAHs as a contributing factor to that classification.<\/p>\n

Silva et al. (2025) found that urinary biomarkers of PAH exposure\u2014particularly 1-hydroxypyrene (1OHPyr)\u2014consistently increased following firefighting activities. In some cases, levels rose up to 12 times higher post-exposure. These findings were observed in both real wildfire scenarios and in controlled training environments (Fent et al., 2019; Cherry et al., 2023).<\/p>\n

The American Conference of Governmental Industrial Hygienists (ACGIH, 2022) sets a Biological Exposure Index (BEI) threshold for 1OHPyr at 2.5 \u00b5g\/L. Several studies reported firefighter samples exceeding this threshold, suggesting that current exposure levels may warrant closer scrutiny.<\/p>\n

While respiratory exposure is a primary concern, the review emphasizes that dermal absorption plays a significant role. Even when firefighters used self-contained breathing apparatus (SCBA), elevated PAH levels were detected, indicating that skin contact with contaminated surfaces or particles may be a substantial exposure route (Rossbach et al., 2020).<\/p>\n

In one Canadian study, skin wipe samples taken from firefighters after wildfire deployments showed a threefold increase in surface contamination with PAHs (Cherry et al., 2023). These findings suggest that protective strategies should address both respiratory and dermal pathways.<\/p>\n

Several studies included in the review identified statistically significant increases in DNA damage among wildland firefighters following exposure to wildfire smoke. For example, Esteves et al. (2025b) reported a 22% increase in primary DNA damage and a 23% increase in oxidative DNA damage post-exposure, using comet assay techniques. These findings were consistent across both smokers and nonsmokers and were correlated with urinary levels of PAH metabolites such as 2-hydroxyfluorene.<\/p>\n

While these biomarkers indicate acute biological responses, the review also emphasizes the importance of considering latency periods associated with genotoxic exposures. According to Jongeneelen (2014) and Andersen et al. (2018), DNA damage from PAHs may contribute to carcinogenic processes that manifest clinically over extended periods\u2014often 5 – 10 – 30 years after initial exposure. This latency underscores the need for longitudinal health monitoring and proactive risk mitigation strategies.<\/p>\n

The review further notes that even exposures below current Biological Exposure Index (BEI) thresholds may be biologically relevant. For instance, Andersen et al. (2018) found DNA damage in peripheral blood mononuclear cells at 1OHPyr concentrations below the ACGIH\u2019s recommended BEI of 2.5 \u00b5g\/L. These findings suggest that repeated or cumulative exposure, rather than isolated high-dose events, may be a more critical determinant of long-term health outcomes.<\/p>\n

Given the potential for delayed onset of disease, the authors recommend that occupational health policies incorporate long-term surveillance and biomonitoring programs. This approach would allow for early detection of biological changes and support evidence-based interventions aimed at reducing chronic disease risk among wildland firefighters.<\/p>\n

Beyond DNA damage, PAHs also trigger inflammation. Firefighters in multiple studies had elevated levels of cytokines like IL-6 and IL-8\u2014markers of systemic inflammation (Cordeiro et al., 2021; Esteves et al., 2025a). These changes can lead to fatigue, increased susceptibility to illness, and long-term immune system disruption.<\/p>\n

On the front lines, the symptoms are more familiar: coughing, headaches, and eye irritation. One Canadian study found that firefighters who wore N95 masks during wildfire rotations reported fewer symptoms and had lower PAH levels in their urine (Cherry et al., 2022). But here is the problem: there\u2019s no certified respiratory PPE specifically designed for wildland firefighting. SCBAs are too heavy and cumbersome for long shifts in remote terrain and existing N95 masks are not designed to filter out all the toxic gases in wildfire smoke.<\/p>\n

Canada experienced over 18 million hectares of wildfire activity in 2023, yet biomonitoring studies specific to Canadian wildland firefighters remain limited. Most research has been conducted in Portugal and the United States, with only a few Canadian studies included in the review (Cherry et al., 2021, 2023).<\/p>\n

This geographical gap highlights the need for expanded research efforts to better understand exposure levels and health outcomes in Canadian contexts.<\/p>\n

Silva et al. (2025) propose several actions to improve occupational health protections for wildland firefighters:<\/p>\n