Abstract
Markers of oxidative stress and inflammation were analysed in the exhaled breath condensate (EBC) and urine samples of 14 workers (mean age 43 ± 7 years) exposed to iron oxide aerosol for an average of 10 ± 4 years and 14 controls (mean age 39 ± 4 years) by liquid chromatography-electrospray ionization-mass spectrometry/mass spectrometry (LC-ESI-MS/MS) after solid-phase extraction. Aerosol exposure in the workplace was measured by particle size spectrometers, a scanning mobility particle sizer (SMPS) and an aerodynamic particle sizer (APS), and by aerosol concentration monitors, P-TRAK and DustTRAK DRX.Total aerosol concentrations in workplace locations varied greatly in both time and space. The median mass concentration was 0.083 mg m−3 (IQR 0.063–0.133 mg m−3) and the median particle concentration was 66 800 particles cm−3 (IQR 16 900–86 900 particles cm−3). In addition, more than 80% of particles were smaller than 100 nm in diameter.Markers of oxidative stress, malondialdehyde (MDA), 4-hydroxy-trans-hexenale (HHE), 4-hydroxy-trans-nonenale (HNE), 8-isoProstaglandin F2α (8-isoprostane) and aldehydes C6–C12, in addition to markers of nucleic acid oxidation, including 8-hydroxy-2-deoxyguanosine (8-OHdG), 8-hydroxyguanosine (8-OHG), 5-hydroxymethyl uracil (5-OHMeU), and of proteins, such as o-tyrosine (o-Tyr), 3-chlorotyrosine (3-ClTyr), and 3-nitrotyrosine (3-NOTyr) were analysed in EBC and urine by LC-ESI-MS/MS.Almost all markers of lipid, nucleic acid and protein oxidation were elevated in the EBC of workers comparing with control subjects. Elevated markers were MDA, HNE, HHE, C6–C10, 8-isoprostane, 8-OHdG, 8-OHG, 5-OHMeU, 3-ClTyr, 3-NOTyr, o-Tyr (all p < 0.001), and C11 (p < 0.05). Only aldehyde C12 and the pH of samples did not differ between groups. Markers in urine were not elevated.These findings suggest the adverse effects of nano iron oxide aerosol exposure and support the utility of oxidative stress biomarkers in EBC. The analysis of urine oxidative stress biomarkers does not support the presence of systemic oxidative stress in iron oxide pigment production workers.
Highlights
Iron nanoparticles belong to 13 priority nanomaterial groups identified by the organisation for economic co-operation and development (OECD) for evaluation of their safety [1]
To the best of our knowledge, this is the first study to examine oxidative stress markers in exhaled breath condensate (EBC) and urine in workers exposed to nano iron oxides
The potential adverse effects of nanoparticles on human health are not well understood and research on this subject is a priority for the OECD, National Institute for Occupational Safety and Health (NIOSH) and European Agency for Safety and Health at Work [45]
Summary
Iron nanoparticles belong to 13 priority nanomaterial groups identified by the organisation for economic co-operation and development (OECD) for evaluation of their safety [1]. There is very little information about potential risks of occupational exposure to engineered nanoparticles during production and processing; this is a widely debated issue. Studies on the effect of occupational exposure to engineered iron oxide nanoparticles have yet to be published [2] and no biological exposure tests have been developed to monitor workers’ exposure [3]. Humans exposed to engineered nanomaterials could have oxidative damage in their respiratory system and in other organs due to systemic effects [3, 4]
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