Firefighters’ exposure to potentially toxic combustion products

Abstract

Epidemiological studies have suggested that firefighters have higher incidences of select cancers, respiratory disease, heart disease and negative reproductive outcomes compared to the general population. An explanation for the increased prevalence of these diseases in firefighters is occupational chemical exposure.\xa0 Firefighters’ occupational chemical exposure is likely to occur during firefighting and training, from contaminated clothing and equipment, and from exposure to elevated chemical concentrations within fire stations.The suite of chemicals that firefighters are exposed to at higher concentrations include polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers\xa0(PBDEs) and organophosphate flame-retardants\xa0(OPFRs). PAHs are ubiquitously formed as a result of incomplete combustion processes. OPFRs and PBDEs are used as flame retardants in a variety of consumer products and can be released from these materials during combustion processes. This PhD aimed to assess the exposure risks and pathways for firefighters to PAHs, OPFRs and PBDEs.In Chapter 2, this project assessed firefighter exposure to these chemicals while attending firefighting activities. PAHs in fire smoke and firefighters’ skin were determined, together with the biomarkers of exposure (OH-PAHs) in their urine before and after attending the fire. Two types of fires were attended, diesel pan fires and particleboard fires. The concentrations of all PAHs were significantly higher in the smoke layer of particleboard fires than in diesel pan fires.\xa0 Similarly, the levels of PAHs deposited on the skin of participants attending the particleboard fires were higher than those attending diesel pan fires.Samples from firefighters who attended particleboard fires showed a significant increase in urinary concentrations of hydroxynaphthalenes, hydroxyfluorenes between pre-burn and post-burn samples. They increased from 5.2 and 0.44 µg.g-1\xa0creatinine to 12 and 1.4 µg.g-1\xa0creatinine, respectively. There was no significant increase in the urinary concentrations of hydroxyphenanthrenes or 1-hydroxypyrene. There were no significant changes in the urinary concentrations of OH-PAHs for firefighters who attended the diesel pan fires, possibly due to the lower levels of PAHs in the fire smoke. \xa0Firefighters from this cohort had slightly higher baseline concentrations of hydroxyphenanthrenes and 1-hydroxypyrene than the average from the Australian population. This is believed to be due to occupational exposure outside of fire exposure.Chapter 3 focuses on the occupational exposure of firefighters and to PAHs, OPFRs and PBDEs through inhalation and dust ingestion/contact in fire stations and a firefighter training ground.\xa0 In Australian fire stations (n=15), median ∑13PAH concentrations were 15 ng.m-3\xa0and\xa03.1 µg.g-1\xa0in air and dust respectively, while the median ∑9\xa0OPFR concentrations were 56 ng.m-3\xa0in air and 84 µg.g-1\xa0in dust, and ∑8\xa0PBDE had a median concentration of 0.78 ng.m-3\xa0in air and 26 µg.g-1\xa0in dust. These concentrations of PAHs, OPFRs and PBDEs were all higher than previously measured in Australian houses and offices. The estimated daily intakes through dust and air for ∑13\xa0PAHs, ∑9\xa0OPFRs and ∑8\xa0PBDEs in firefighters were 3.6\u202f,17 and 1.6 ng.kg body weight-1.day-1, respectively. The worst-case estimated daily intakes were only 2% of the reference doses for individual chemicals. Correlations with chemical concentrations for several PAHs, OPFRs and PBDEs were found between the number of years since fire stations were last renovated, as well as the storage locations of firefighting ensembles. This indicated these chemicals are accumulating in fire stations over time, and that firefighting ensembles might be a source of these chemicals in fire stations. This was followed up in Chapter 4, where air and dust were sampled from a building at a firefighting training ground. The concentrations of OPFRs and PBDEs in the firefighter training ground were comparable to concentrations previously measured in Australian houses and offices. While, ∑13PAH concentrations ranged from 25-870 ng.m-3\xa0in air and\xa022-230 µg.g-1\xa0in dust respectively, with the lowest levels of PAHs being measured in the fire trainers’ offices. The higher concentrations of PAHs the firefighter training ground building are most likely due to the large number of fires attended at the training ground as well as the proximity of these fires. The lower concentrations of PAHs measured in the fire trainers’ offices compared to the rest of the training ground suggest that demarcation of clean and dirty areas in the training ground building reduces the amount of PAHs getting tracked back into the offices.With firefighting ensembles potentially contributing to the load of PAHs, OPFRs and PBDEs in fire stations. Chapters 5 and 6 focus on the concentrations of PAHs, OPFRs and PBDEs in firefighting ensembles, the efficiency of decontamination and whether/how these ensembles may contaminate firefighters’ microenvironments, such as vehicles and fire stations, and lead to further exposure routes. The concentrations of firefighting ensembles pre- and post-laundering were measured in Chapter 5. The concentrations of ∑13\xa0PAHs, ∑6\xa0OPFRs and ∑7\xa0PBDEs in uniforms ranged from 0.063 – 43 µg.g-1, 0.061 – 90 µg.g-1, and 0.00054 – 0.97 µg.g-1, respectively. The highest concentrations of ∑13\xa0PAHs and\xa0 ∑6\xa0OPFRs were measured on gloves, while the\xa0 highest ∑7\xa0PBDEs concentrations were found on turnout jackets. A significant reduction in ∑13\xa0PAHs after laundering was found in three of the 16 sampled areas from firefighting uniforms. No significant differences were found between the pre- and post- laundering concentrations of ∑6\xa0OPFRs or ∑7\xa0PBDEs in firefighting uniforms.The current laundering techniques do not appear to effectively remove PAHs, OPFRs and PBDEs from firefighters’ uniforms. This may lead to a potential exposure risk to firefighters, as they often store firefighting ensembles in private vehicles when off duty. Therefore, Chapter 6 investigates the concentrations of PAHs, OPFRs and PBDEs that off gas from firefighting uniforms and assesses if these concentrations in a vehicle cabin could be a significant source of exposure to firefighters. The concentrations of ∑13\xa0PAHs, ∑6\xa0OPFRs and ∑7\xa0PBDEs that off gassed from a laundered firefighting ensemble in a vehicle were 12000, 1200 and 53 ng.day-1. This is potentially an important pathway for exposure to firefighters that had not previously been examined.Overall, this project provides an insight into the exposure firefighters have to PAHs, OPFRs and PBDEs, from within fire stations, while attending fires and potentially from firefighting uniforms. The main outcomes from this thesis are the observation of higher baseline concentrations of hydroxyphenanthrenes and 1-hydroxypyrene in firefighters’ urine than the general population, current decontamination techniques not effectively removing semivolatile organic chemicals (SVOCs) from firefighters’ uniforms and firefighting uniforms contributing to the load of SVOCs in the micro-environments they are stored. By understanding the significance of these exposure pathways, future strategies for reducing chemical exposure to firefighters can be assessed.