# Effects of Workers Exposure to Nanoparticles Studied by NMR Metabolomics
###### Abstract  
In this study, the effects of occupational exposure to nanoparticles (NPs) were studied by NMR metabolomics. Exhaled breath condensate (EBC) and blood plasma samples were obtained from a research nanoparticles-processing unit at a national research university. The samples were taken from three groups of subjects: samples from workers exposed to nanoparticles collected before and after shift, and from controls not exposed to NPs. Altogether, 60 \({}^{1}\)H NMR spectra of exhaled breath condensate (EBC) samples and 60 \({}^{1}\)H NMR spectra of blood plasma samples were analysed, 20 in each group. The metabolites identified together with binning data were subjected to multivariate statistical analysis, which provided clear discrimination of the groups studied. Statistically significant metabolites responsible for group separation served as a foundation for analysis of impaired metabolic pathways. It was found that the acute effect of NPs exposure is mainly reflected in the pathways related to the production of antioxidants and other protective species, while the chronic effect is manifested mainly in the alteration of glutamine and glutamate metabolism, and the purine metabolism pathway. NMR metabolomics; human plasma; exhaled breath condensate; nanoparticles exposure +
Footnote †: journal:  
to larger particles of the same chemical composition that are little or even non-toxic by themselves [2; 10; 16; 17]. For humans, inhalation is probably the most common way of NPs access followed by oral and dermal routes of exposure. Inhaled NPs can be deposited throughout the human respiratory system including pharyngeal, nasal, transbronchial and alveolar regions, depending on the particle size. The fractional deposition efficiency of particles below 100 nm is in the range of 30-70% in pulmonary regions, and the alveolar deposition increases as the size of NPs decreases [2; 16; 17; 18]. After deposition in the respiratory tract, NPs may penetrate through membranes and thus enter the blood, pulmonary interstitium, brain, liver, heart, spleen and possibly to the foetus in pregnant females. Since NPs can have the same dimensions as some biomolecules, such as proteins and nucleic acids, adsorption and subsequent disruption of their structure are also possible [2; 3; 10; 11; 19]. The existing toxicological methodology for NPs still requires further adjustment to properly assess the risks, including the transport and distribution of NPs in the human body and the mechanism of interaction at the subcellular and molecular level, and to extrapolate the results from in vitro and animal models experiments, which may explain the human health deterioration. Another challenge of this field is to find a fast, specific and sensitive way to evaluate occupational risk. So far, the number of human studies is very limited. As the main exposure to NPs takes place via inhalation and the respiratory system is the primary afflicted organ system, collection and analysis of exhaled breath condensate (EBC) is the most frequently used non-invasive technique for assessment of a subject's condition. EBC contains, besides water, a small proportion of inorganic ions, small organic molecules, proteins and other macromolecules. Analysis of EBC enables the determination of important biomarkers as a response to current physiological conditions [20]. Recently, two toxicological studies were performed on a cohort of 20 workers exposed to NPs during their occupation [12; 13]. A detailed analysis of lung function parameters obtained by spirometry revealed a significant decline of forced expiratory volume (FEV1) and its ratio to forced vital capacity (FVC) when compared to the pre-shift values or to the control group. These data were accompanied by LC-MS analysis of inflammation markers in EBC. The levels of pro-inflammatory markers LTB4, LTD4, LTE4, IL 9 and TNF were found to be increased in the worker group relative to controls. On the other hand, the levels of anti-inflammatory LXB4 and IL 10 were lower in the worker group than in controls.