Firefighters’ exposure to perfluoroalkyl acids and 2-butoxyethanol present in firefighting foams
Introduction
Perfluoroalkyl acids (PFAAs), including perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS), are a subgroup of per- and polyfluorinated alkyl substances (PFAS). These substances have been widely used in many industrial and commercial applications. The chemical and thermal stability of a perfluoroalkyl moiety, which is caused by the very strong CF bond, in addition to its hydrophobic and lipophobic nature, lead to highly useful and enduring properties in surfactants and polymers (Fromme et al., 2009).
One of the surfactant applications is in aqueous film-forming foams (AFFFs) used to extinguish hydrocarbon-fuel and chemical solvent fires. The foams acts to both cool the fire and to coat the fuel, preventing its contact with oxygen. This can happen with the help of PFAA compounds or fluorotelomers and hydrocarbon surfactants such as sodium alkyl sulfate (Oakes et al., 2010, Place and Field, 2012). They form a film of aqueous solution covered on both sides by monolayers of mixed surfactants (Moody and Field, 2000). Other common ingredients in AFFFs are solvents, of which the most common are 2-butoxyethanol (EGBE), 2-(2-butoxyethoxy) ethanol (DEGBE) and 1,2-ethanediol (EG), which are required for the stabilization of the surfactants and foam, and they also act as anti-freezing agents (Moody and Field, 2000, Paloposki, 2013).
Studies with PFAAs have shown that these compounds may increase total and LDL cholesterol as well as the risk of breast cancer (Nelson et al., 2009, Steenland et al., 2009, Frisbee et al., 2010, Bonefeld-Jorgensen et al., 2011). Recently, it has been shown that there is a link between the exposure to PFAAs and the disruption of thyroid hormones (Bloom et al., 2010, Lopez-Espinosa et al., 2012). This is a very important finding concerning firefighters’ exposure to AFFFs. Similar effects have been found in firefighters’ exposure to fire retardant (Shaw et al., 2013). These compounds together might have additive or even synergistic effects on firefighters' thyroid hormones.
Dietary intake is believed to be the major exposure route for PFAAs in the general adult population (Fromme et al., 2009, Haug et al., 2011). In addition to food and environmental background exposure to PFAAs, an occupational exposure can play an important role in total exposure (Fromme et al., 2009). During the suppression of a liquid fire, firefighters may be exposed to AFFFs through inhalation and dermal exposure routes. Contaminated personal protective equipment and firefighting suits might also increase the risk of hand-to-mouth transfer and eventual exposure via the gastrointestinal tract. The washing of these equipment is still a big problem for fire brigades in Finland and the use of contaminated firefighting suits is a very common practice. Thus, firefighters’ short and also long term occupational exposure to PFAA compounds seems to be more than evident.
Due to persistence and bioaccumulative properties, including the potent harmful and toxic effects of PFOA and PFOS, the EU decided to ban their use in the majority of applications, including AFFFs. In June 2012 fire brigades were required to stop using of AFFFs containing PFOS and PFOA. The banning of PFOS and PFOS raised the question in fire brigades: What replacement options are there for firefighting foams in future? On the other hand, there was a need to estimate firefighters’ exposure to AFFFs in training simulations of aircraft accidents.
In this study, firefighters’ exposure to 12 PFAAs and EGBE was assessed by biomonitoring methods during three consecutive firefighting training sessions in 2010 at the Oulu airport in Finland. Sthamex 3% AFFF was used as the extinguishing foam for jet fuel fires during training. Additionally, eight commercially available firefighting foams in Finland were evaluated from occupational, environmental and technical points of view in order to find possible replacements for the future.
Section snippets
Study subjects
This study was carried out during training for the suppression of liquid fires in aircraft accident simulations. Eight male firefighters from the Oulu Airport Fire Brigade in Finland participated in three consecutive training sessions held over a three month period in 2010. In each training simulation the length of individual firefighters’ smoke diving sessions varied from 60 to 63 min. These training sessions were carried out in a conventional aircraft accident simulator and in training
PFAA concentrations in AFFF liquids
The concentrations of PFAAs in the Sthamex 3% AFFF liquid used in all trainings were analyzed. The most abundant PFAAs in the AFFFs were PFOS and PFOA, which is in agreement with a previous study (Backe et al., 2013). The detected average concentrations of PFOS and PFOA in the Sthamex 3% AFFF liquid were 240 μg/mL and 21 μg/mL, respectively. Low concentration of PFHxA and PFNA were also detected, but the concentrations were below the LOQ (limit of quantification).
PFAA concentrations in serum
Total serum PFAA concentrations
Conclusions
The PFHxS and PFNA levels seemed to increase, after the three consecutive training sessions compared to the firefighters’ individual baseline concentrations in samples taken two weeks before the first exposure period. Statistical significance between PFAS levels in the beginning and end of the study was not able to carry out due to the limited size of test group. Interesting was note that elevated PFAS levels were not the main PFAS in used AFFF. Explanation for that might be the other PFAS
Conflict of interest
The authors declare that there are no conflicts of interest.
Acknowledgements
This project was funded by the Occupational Safety and Health Fund of the State Sector. We also thank Christopher Keith for assistance with the language revision.
References (32)
- et al.
Exploratory assessment of perfluorinated compounds and human thyroid function
Physiol. Behav.
(2010) - et al.
Perfluorinatedcompounds – exposure assessment for the general population in western countries
Int. J. Hyg. Environ. Health
(2009) - et al.
Characterisation of human exposure pathways to perfluorinated compounds – comparing exposure estimates with biomarkers of exposure
Environ. Int.
(2011) - et al.
Simple tests to determine urinary risk factors and calcium oxalate crystallization in the outpatient clinic
Urol
(1991) - et al.
Determination of selected perfluorinated alkyl acids and persistent organic pollutants from a small volume human serum sample relevant for epidemiological studies
J. Chromatogr. A
(2013) - et al.
Biomonitoring of perfluorochemicals and toxicity to the downstream fish community of Etobicoke Creek following deployment of aqueous film-forming foam
Aquat. Toxicol.
(2010) - et al.
Persistent organic pollutants including polychlorinated and polybrominated dibenzo-p-dioxins and dibenzofurans in firefighters from Northern California
Chemosphere
(2013) - et al.
Thermal degradation of fluorotelomer treated articles and related materials
Chemosphere
(2005) - et al.
Zwitterionic, cationic, and anionic fluorinated chemicals in aqueous film forming foam formulations and groundwater from U.S. military bases by nonaqueous large-volume injection HPLC–MS/MS
Environ. Sci. Technol.
(2013) - et al.
Serum concentrations of perfluorinated alkyl acids and their associations with diet and personal characteristics among Swedish adults
Mol. Nutr. Food Res.
(2013)
Perfluorinated compounds are related to breast cancer risk in greenlandic inuit: a case control study
Environ. Health
Degradation of fluorotelomer alcohols: a likely atmospheric source of perfluorinated carboxylic acids
Environ. Sci. Technol.
Dermal penetration potential of perfluorooctanoic acid (PFOA) in human and mouse skin
J. Toxicol. Environ. Health A
Perfluorooctanoic acid, perfluorooctanesulfonate, and serum lipids in children and adolescents: results from the C8 health project
Arch. Pediatr. Adolesc. Med.
Compound-specific: quantitative characterization of organic fluorochemicals in biological matrices
Environ. Sci. Technol.
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