Recently there has been an exponential increase in the number of studies focused on chemical exposure to firefighters. It has already been determined that firefighters have an increased risk of certain cancers and other health conditions. It is believed that the exposure firefighters face to the myriad of chemicals present within fire smoke may be a contributing factor.
These chemicals, present in the form of gases and particulates, can be absorbed dermally (through the skin), be inhaled, or be ingested. Firefighters can be exposed through fire incidents, or by secondary exposure through the handling of contaminated equipment and clothing or though exposure to fire station air and dust. Dust exposure is important as humans eat a considerable amount of dust every day (unbeknownst to us!), and chemicals can be dermally absorbed though dust on or skin.
In Australia there are an increasing number of conversations around cancer and firefighters, followed by the recent introduction of presumptive cancer legislation across States and Territories. This makes understanding the sources of chemical exposure to firefighters in Australia of key importance.
Recent research has been undertaken involving the comprehensive monitoring of Australian fire stations to determine the levels of flame retardants (OPFRs and PBDEs), polycyclic aromatic hydrocarbons (PAHs), and metals in fire station air and dust. Many of the assessed chemicals are identified as possible or known carcinogens by the International Agency for Research on Cancer.
Between the periods of November 2017-Feb 2018, 15 representative fire stations were selected based on a range of fire station attributes including the average number of actual fires attended per annum, the age of the building, the layout of the station, engine bay design (drive through or reverse in), and the storage location of personal protective clothing (PPC) within the fire station. The selected stations were all urban fire stations. The PPC stored in these fire stations was primarily structural firefighting jackets and over pants (turnout gear), though bushfire jackets were present also. The stations included ten staffed 24 hours a day, three staffed in an on-call manner, and two stations sharing both employment types.
An air sampler was placed in each fire station in a position appropriate given the layout of each station, and it remained there for approximately 80 days. This sampler worked by having chemicals in air diffuse into the polyurethane disk in the air sampler, and having dust fall out of the air onto a glass fibre filter. Dust samples were collected from fire stations using a modified vacuum cleaner, samples were taken as follows: one sample for the total living quarters of each station, one sample for the PPC location in each station (one station had two locations), and one sample from within each fire truck. Surface wipe samples were taken across the 15 stations; sampling PPC, inside the vehicle cabin, and within the station living quarters.
Once samples were analysed the collected fire station data was compared with houses and offices, and correlations were sought to understand what factors may be contributing to the increased chemical contamination within fire stations. Exposure assessments based on the amount of air inhaled, dust ingested and dermal contact with dust were undertaken to better understand what exposure to these chemicals may mean for firefighters. All groups of chemicals measured were found to be higher in Australian fire stations compared to houses and offices, some by orders of magnitude.
In fire station dust, the majority of correlations between station characteristics and chemical concentrations were found in the living quarters of fire stations. These correlations were found in the living quarters of fire station because this is where carpet was present within the fire station. Carpet is able to act like a long-term sampler of dust. Age of building (renovated age) showed positive correlations across PAHs, and flame retardants in dust from living quarters. Negative correlations were found between dust in living quarters and PPC stored outside of the station.
Air monitoring showed positive correlations between chemical concentrations of flame retardants and PPC storage location being in a thoroughfare within the living quarters of the station. This correlation was reversed when PPC was stored outside the station. These correlations, coupled with those found when assessing dust profiles, support that PPC is a source of these chemicals in fire stations and their proximity to the rest of the station determines how much they contribute to the chemical load.
Surface wipe samples for metals found that the type of fire attended was significantly correlated to PPC contamination. Threshold tests were run (binomial tests) to ascertain the levels of exposure that presented a tipping point for contamination wherein the PPC became statistically significantly more contaminated. This information was overlaid with laundering history for each item wiped. Results showed that firefighters are not laundering their PPC in line with threshold test results, and that PPC should be laundered after every fire (whether it be a wildfire, vehicle or structure fire) to reduce surface metal concentration.
When assessing human exposure, the wipe samples showed that 6% of PPC and 10% of items wiped within fire stations (mainly breathing apparatus wash sinks) demonstrated an exposure to carcinogenic metals that may cause possible risk. It is important to note that these calculations of possible risk only include exposure to metals. The median estimated daily intake (EDI) through dust and air found firefighters to exceed the exposure levels of office workers. Results showed the sum of measured PAHs to be 1.9 times higher, while the sum of measured OPFRs was 1.2 times higher, and the sum of measured PBDEs was 4.8 times higher. The individual chemical PBDE-99 exposure stood out, being 70 times higher for firefighters than office workers.
Overall, median EDIs for PAHs and flame retardants, were 3-7 orders of magnitudes lower than reference doses (lowest expected adverse effect dose) and the worst-case scenario EDI was below 2% of the reference dose. Although the EDI are well below the reference doses, this only considers exposure of these chemicals though the air and dust in fire stations and houses. For the general population, dietary exposure to flame retardant contribute much more to the overall internal dose than air and dust. This increased risk of exposure of firefighters to PAHs and flame retardants in the fire station is still of concern due to other sources that are not represented in this exposure assessment, such as the acute exposure at fire scenes and through the handling of contaminated PPC and equipment after fire attendance.
This study demonstrated that Australian fire stations exhibit a higher level of chemical contamination to a range of chemical groups when compared with houses and offices. The source of these chemicals is likely fires, with contamination being tracked back into fire stations after incidents. Fire stations, vehicle and PPC are assumed to be in a clean and ready state at all times, thereby not increasing firefighter exposure away from the fire incidents, the findings from this study suggest otherwise. Furthermore, given the frequent participation of firefighters in community activities, including having children visiting stations and climbing into fire trucks, the presence of this elevated chemical contamination warrants consideration. This study coupled with international research shows that the decontamination of equipment at the incident as well as the isolation of PPC (bagging and tagging) prior to returning to the fire station are likely to have a prominent effect on the reduction in contamination of fire stations. Fire Services and firefighters need to work together to support these changes, by supporting the laundering of PPC after every fire and decontaminating all equipment used at the fire (including washing vehicles if they are exposed to smoke).
This station monitoring is part of a much larger study on firefighter exposure, including firefighter biomonitoring (analysing blood, urine, semen and breast milk samples to understand the levels of chemicals within firefighter systems), sampling uniforms pre and post fire exposure, and assessing the effectiveness of decontamination through laundering PPC. The other sections of the study are still being undertaken.
The firefighter biomonitoring section of the study will help to understand what chemicals are elevated in firefighter systems, and what factors may be playing a role. For example, frequency of exposure, personal and station hygiene, and types of exposure. The survey and sample collection for this extensive study is continuing until June 2021, so please get involved ASAP. Involvement is free, anonymous and confidential, and open to any Australian firefighter aged 18 and over. If you care about knowing more about firefighter health and exposures, please take a moment and participate. Your contribution will have positive ripple effects for firefighting communities around the world. www.surveymonkey.com/r/firefighterresearch.
For more information please access the following two published papers surrounding this research study: Engelsman et al 2019 – Exposure to metals and semivolatile organic compounds in Australian fire, Banks et al 2019 – The occurrence of PAHs and flame-retardants in air and dust from Australian fire stations.
For more information, go to www.fire.nsw.gov.au