RESUMEN
Firefighters can be occupationally exposed to a wide range of airborne pollutants during fire-extinguishing operations. The overall study aim was to characterize occupational exposure to smoke for several groups of workers responding to fires, with specific aims to determine the correlations between exposure markers and to biologically assess their systemic exposure to polycyclic aromatic hydrocarbons (PAHs) in urine. Personal exposure measurements of equivalent black carbon (eBC), elemental carbon (EC), organic carbon (OC), nitrogen dioxide (NO2), PAHs, lung deposited surface area (LDSA), and particle number concentration (PNC) of ultrafine particles were performed on firefighters, observers, and post-fire workers during firefighting exercises. Urine samples were collected before and after exposure and analyzed for PAH metabolites. Additional routes for PAH skin exposure were investigated by wipe sampling on defined surfaces: equipment, personal protective equipment (PPE), and vehicles. Among workers without PPE, observers generally had higher exposures than post-fire workers. The observers and post-fire workers had an occupational exposure to smoke measured e.g. as EC of 7.3 µg m-3 and 1.9 µg m-3, respectively. There was a good agreement between measurements of carbonaceous particles measured as EC from filters and as eBC with high time resolution, especially for the observers and post-fire workers. Ultrafine particle exposure measured as LDSA was two times higher for observers compared to the post-fire workers. The urinary levels of PAH metabolites were generally higher in firefighters and observers compared to post-fire workers. Investigation of PAH contamination on firefighters' PPE revealed high PAH contamination on surfaces with frequent skin contact both before and after cleaning. Exposure to smoke can be assessed with several different exposure markers. For workers residing unprotected around fire scenes, there can be high peak exposures depending on their behavior concerning the smoke plume. Several workers had high urinary PAH metabolite concentrations even though they were exposed to low air concentrations of PAHs, indicating skin absorption of PAH as a plausible exposure route.
RESUMEN
BACKGROUND: Per- and polyfluoroalkyl substances (PFAS) are persistent substances with surfactant and repellent properties. Municipal drinking water contaminated with PFAS had been distributed for decades to one third of households in Ronneby, Sweden. The source was firefighting foam used in a nearby airfield since the mid-1980s. Clean water was provided from December 16, 2013. AIMS: The purpose was to estimate serum half-lives and their determinants in the study population for different PFAS. METHODS: Up to ten blood samples were collected between 2014 and 2018 from 114 participants (age 4-84 years at entry, 53% female). 19 PFAS were analysed. Linear mixed models were used to estimate the half-lives. RESULTS: Eight PFAS were increased in Ronneby: perfluorooctanoic acid (PFOA), perfluoropentane sulfonate (PFPeS), perfluorohexane sulfonate (PFHxS), perfluoroheptane sulfonate (PFHpS), linear perfluorooctane sulfonate (L-PFOS) and three branched perfluorooctane sulfonates (1 m-PFOS, 3/4/5m-PFOS and 2/6m-PFOS). The mean estimated half-lives (in years) were 0.94 (95 %CI 0.86-1.02) for PFPeS, 2.47 (2.27-2.7) for PFOA, 2.67 (2.51-2.85) for 2/6m-PFOS, 2.73 (2.55-2.92) for L-PFOS, 3.43 (3.19-3.71) for 3/4/5m-PFOS, 4.52 (4.14-4.99) for PFHxS, 4.55 (4.14-5.06) for PFHpS, and 5.01 (4.56-5.55) for 1 m-PFOS. The most important determinants of a shorter half-life were young age, and better kidney function measured by estimated glomerular filtration rate and ratio of paired urine and serum PFAS levels, followed by female sex during their fertile period aged 15-50. Markers of gut inflammation and reduced permeability i.e. zonulin and calprotectin were also possibly associated with shorter half-life. The results also suggested a time-dependent PFAS elimination process, with more rapid elimination in the first year after the end of exposure. CONCLUSION: The half-life estimates are in line with past estimates for some PFAS such as PFOA, and the novel results for different PFOS isomers. These results provide observational support for elimination routes - renal, fecal and maternal.
