Airport emission particles: exposure characterization and toxicity following intratracheal instillation in mice

Abstract

Background Little is known about the exposure levels and adverse health effects of occupational exposure to airplane emissions. Diesel exhaust particles are classified as carcinogenic to humans and jet engines produce potentially similar soot particles. Here, we evaluated the potential occupational exposure risk by analyzing particles from a non-commercial airfield and from the apron of a commercial airport. Toxicity of the collected particles was evaluated alongside NIST standard reference diesel exhaust particles (NIST2975) in terms of acute phase response, pulmonary inflammation, and genotoxicity after single intratracheal instillation in mice. Results Particle exposure levels were up to 1 mg/m 3 at the non-commercial airfield. Particulate matter from the non-commercial airfield air consisted of primary and aggregated soot particles, whereas commercial airport sampling resulted in a more heterogeneous mixture of organic compounds including salt, pollen and soot, reflecting the complex occupational exposure at an apron. The particle contents of polycyclic aromatic hydrocarbons and metals were similar to the content in NIST2975. Mice were exposed to doses 6, 18 and 54 μg alongside carbon black (Printex 90) and NIST2975 and euthanized after 1, 28 or 90 days. Dose-dependent increases in total number of cells, neutrophils, and eosinophils in bronchoalveolar lavage fluid were observed on day 1 post-exposure for all particles. Lymphocytes were increased for all four particle types on 28 days post-exposure as well as for neutrophil influx for jet engine particles and carbon black nanoparticles. Increased Saa3 mRNA levels in lung tissue and increased SAA3 protein levels in plasma were observed on day 1 post-exposure. Increased levels of DNA strand breaks in bronchoalveolar lavage cells and liver tissue were observed for both particles, at single dose levels across doses and time points. Conclusions Pulmonary exposure of mice to particles collected at two airports induced acute phase response, inflammation, and genotoxicity similar to standard diesel exhaust particles and carbon black nanoparticles, suggesting similar physicochemical properties and toxicity of jet engine particles and diesel exhaust particles. Given this resemblance as well as the dose-response relationship between diesel exhaust exposure and lung cancer, occupational exposure to jet engine emissions at the two airports should be minimized. Electronic supplementary material The online version of this article (10.1186/s12989-019-0305-5) contains supplementary material, which is available to authorized users.

Particle characterization and toxicity in C57BL/6 mice following instillation of five different diesel exhaust particles designed to differ in physicochemical properties

“…Carbon black nanoparticles did not induce DNA strand breaks in the current study, but we have previously found CB-induced DNA strand breaks in BAL, lung and liver following inhalation and instillation [5,22,36,44,62,74,75]. We used 0.1%tween as vehicle, since not all the DEPs could be dispersed satisfactory in pure water or 2% serum, which are the preferred vehicles [12,40,41,42,43,44,45]. We have previously compared the effect of vehicle on CB-, TiO 2 -and CNT-induced toxicity [35].…”

“…This could be due to the low level of inflammation caused by the relatively low dose levels used in the current study. The standard diesel exhaust particles NIST2975 and NIST1650b did not induce neutrophil influx at 54 ug/mouse 28 days post-exposure in similar experimental set-ups [12,62].…”

“…Saa3 mRNA levels have been shown to correlate closely with neutrophil influx and deposited surface area for insoluble particles such as CB and TiO 2 nanoparticles and carbon nanotubes [10,19,44,46]. We have previously shown that pulmonary exposure to NIST2975 induced pulmonary Saa3 expression as well as increased plasma levels of SAA3 [12] and that pulmonary Saa3 expression correlate with plasma SAA3 protein levels [67]. In the current study, Saa3 mRNA levels correlated closely with neutrophil influx and deposited EC, but poorly with estimated deposited surface area on day 1 post-exposure.…”

“…The metal analysis was carried out as previously described in Bendtsen et al [12], but with slightly modi ed extraction times. Brie y, as it was not possible to transfer the amount of ≤ 1 mg particle matter from the received vials to containers suitable for microwave-assisted acid digestion, a volume of 1 mL of 25 % (v/v) nitric acid was directly added to the vials.…”

“…The classi cation of diesel exhaust as carcinogenic [1] and the reported diesel particle airway toxicity and systemic effects in both humans [2,3,4] and in mice [5,6,7,8,9,10,11,12] necessitates further studies.…”