Environmentally Relevant Iron Oxide Nanoparticles Produce Limited Acute Pulmonary Effects in Rats at Realistic Exposure Levels.
Iron is typically the dominant metal in the ultrafine fraction of airborne particulate matter. Various studies have investigated the toxicity of inhaled nano-sized iron oxide particles (FeOxNPs) but their results have been contradictory, with some indicating no or minor effects and others finding effects including oxidative stress and inflammation. Most studies, however, did not use materials reflecting the characteristics of FeOxNPs present in the environment. We, therefore, analysed the potential toxicity of FeOxNPs of different forms (Fe3O4, α-Fe2O3 and γ-Fe2O3) reflecting the characteristics of high iron content nano-sized particles sampled from the environment, both individually and in a mixture (FeOx-mix). A preliminary in vitro study indicated Fe3O4 and FeOx-mix were more cytotoxic than either form of Fe2O3 in human bronchial epithelial cells (BEAS-2B). Follow-up in vitro (0.003, 0.03, 0.3 µg/mL, 24 h) and in vivo (Sprague-Dawley rats, nose-only exposure, 50 µg/m3 and 500 µg/m3, 3 h/d × 3 d) studies therefore focused on these materials. Experiments in vitro explored responses at the molecular level via multi-omics analyses at concentrations below those at which significant cytotoxicity was evident to avoid detection of responses secondary to toxicity. Inhalation experiments used aerosol concentrations chosen to produce similar levels of particle deposition on the airway surface as were delivered in vitro. These were markedly higher than environmental concentrations. No clinical signs of toxicity were seen nor effects on BALF cell counts or LDH levels. There were also no significant changes in transcriptomic or metabolomic responses in lung or BEAS-2B cells to suggest adverse effects.
['Guo|Chang|C|0000-0002-9662-1885', 'Weber|Ralf J M|RJM|', 'Buckley|Alison|A|', 'Mazzolini|Julie|J|', 'Robertson|Sarah|S|', 'Delgado-Saborit|Juana Maria|JM|0000-0002-7096-9744', 'Rappoport|Joshua Z|JZ|', 'Warren|James|J|', 'Hodgson|Alan|A|', 'Sanderson|Paul|P|', 'Chipman|James Kevin|JK|', 'Viant|Mark R|MR|0000-0001-5898-4119', 'Smith|Rachel|R|']
D055371:Acute Lung Injury D000336:Aerosols D000393:Air Pollutants D000818:Animals D002460:Cell Line D006801:Humans D007249:Inflammation D019570:Inhalation Exposure D008168:Lung D000082662:Magnetic Iron Oxide Nanoparticles D052638:Particulate Matter D051381:Rats D017207:Rats, Sprague-Dawley
iron oxide nanoparticle rat ultrafine inhalation lung omics