Abstract
Contamination of aircraft cabin air can result from leakage of engine oils and hydraulic fluids into bleed air. This may cause adverse health effects in cabin crews and passengers. To realistically mimic inhalation exposure to aircraft cabin bleed-air contaminants, a mini bleed-air contaminants simulator (Mini-BACS) was constructed and connected to an air-liquid interface (ALI) aerosol exposure system (AES). This unique "Mini-BACS+AES" setup provides steady conditions to perform ALI exposure of the mono- and co-culture lung models to fumes from pyrolysis of aircraft engine oils and hydraulic fluids at respectively 200°C and 350°C. Meanwhile, physicochemical characteristics of test atmospheres were continuously monitored during the entire ALI exposure, including chemical composition, particle number concentration (PNC) and particles size distribution (PSD). Additional off-line chemical characterization was also performed for the generated fume. We started with submerged exposure to fumes generated from 4 types of engine oil (Fume A, B, C, and D) and 2 types of hydraulic fluid (Fume E and F). Following submerged exposures, Fume E and F as well as Fume A and B exerted the highest toxicity, which were therefore further tested under ALI exposure conditions. ALI exposures reveal that these selected engine oil (0-100mg/m3) and hydraulic fluid (0-90mg/m3) fumes at tested dose-ranges can impair epithelial barrier functions, induce cytotoxicity, produce pro-inflammatory responses, and reduce cell viability. Hydraulic fluid fumes are more toxic than engine oil fumes on the mass concentration basis. This may be related to higher abundance of organophosphates (OPs, ≈2800µg/m3) and smaller particle size (≈50nm) of hydraulic fluid fumes. Our results suggest that exposure to engine oil and hydraulic fluid fumes can induce considerable lung toxicity, clearly reflecting the potential health risks of contaminated aircraft cabin air.
Highlights
Concerns have been raised regarding the potential health risks of exposure to contaminated air in aircraft cabins (Michaelis, 2011; Ramsden, 2012; Winder and Michaelis, 2005)
As well as enzyme-linked immunosorbent assay (ELISA) kits for measuring interleukin (IL)-6, IL8, IL-10 and tumor necrosis factor (TNF)-α were purchased from Life Technologies (Thermo Fisher Scientific Inc., the Netherlands); WST assay kit was purchased from Promega (Fitchburg, Wisconsin, USA); lactate dehydrogenase (LDH) detection kit was purchased from Roche Diagnostics (Mannheim, Germany); All other chemicals, unless otherwise noted, were purchased from Sigma Aldrich
In accordance with the European Food Safety Authority (EFSA) as well as taking the variation of the data into account, a 20% increase compared to incubator controls in total levels of LDH release and inflammatory cy tokines production was chosen as a benchmark response (BMR) for modelling (EFSA, 2009)
Summary
Concerns have been raised regarding the potential health risks of exposure to contaminated air in aircraft cabins (Michaelis, 2011; Ramsden, 2012; Winder and Michaelis, 2005). Health effects reported by a fraction of aircraft cabin crews include cough, sore throat, nausea, dizziness, disorientation, and tremors during flight Those health com plaints, which are sometimes collectively referred to as “aerotoxic syn drome” (Michaelis et al, 2017; Van Netten, 2005), have been associated with exposure to cabin air contaminants, during so-called fume events (Abou-Donia et al, 2013; Brown et al, 2001; Reneman et al, 2016; Winder and Michaelis, 2005). Bleed air passes through the air conditioning system (socalled “PACKs”) of the Environmental Control System (ECS) before being distributed to aircraft cabin and cockpit During this process, bleed air contamination may occur, for example, due to oil leaks. Oils from those leaks are subjected to high temperatures and their
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