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  • Particulate matter was characterized in

    2018-10-23

    Particulate matter was characterized in broncho-alveolar lavage fluid (BALF) extracts and in situ in AM of asthmatic Parisian children. Asthmatic patients, rather than healthy subjects, were selected for the study since fiber-optic bronchoscopy with broncho-alveolar lavage is routinely performed in France as a diagnostic tool for other missed diseases with symptoms similar to phospholipase a2 inhibitor (Just et al., 2002). Obviously, such an invasive method is ethically difficult to consider for healthy subjects.
    Methods
    Results
    Discussion Among different indoor and outdoor combustion-derived airborne PM, carbonaceous particles represent an important fraction of pollutants (Cherukuri et al., 2004; Murr et al., 2004; Murr and Guerrero, 2006). These generally contain amorphous carbon, but, interestingly, may also contain carbon nanotubes (CNTs) and fullerenes (Murr et al., 2004; Murr and Guerrero, 2006; Lagally et al., 2012). Such findings suggest that humans may have always been exposed to CNTs. However, it is unknown whether, and to what extent, CNTs penetrate the lower respiratory tract. In 2010 a study reported that CNTs were extracted from the lungs of the victims of the World Trade Center attack (Wu et al., 2010). However, this report cannot be generalized to environmental exposure. In addition, samples were only observed by low magnification TEM, which may not provide conclusive evidence, and CNTs were not visualized inside the cells. To characterize CNTs, only a limited number of techniques are useful (Belin and Epron, 2005). Only HRTEM and scanning tunneling microscopy are able to characterize CNTs at the individual level. EDX is needed to characterize the elemental composition of CNTs, while neutron and X-ray diffraction, NIRFM and Raman spectroscopy are global characterization techniques (Belin and Epron, 2005). Taken together, our results show that PM is mostly composed of anthropogenic MWCNTs in all analyzed samples. These results also show that PM is impossible to distinguish from LBs by optical microscopy. Thus, results of previous studies, where carbon content of AMs was assessed by optical microscopy only (Kulkarni et al., 2006; Brugha et al., 2014), need to be reconsidered. TEM can be used to detect CNT-like structures, but this demands a highly trained person. In order to look for the presence of some SWCNTs among CNTs found inside the cells, we also used NIRFM. NIRFM data were positive for two of the five examined fresh BALF samples. Although only individualized semiconducting SWCNTs are NIRF emissive (Cherukuri et al., 2004), these observations strongly support the presence of SWCNTs in some of the samples. Although the number of examined samples is limited, the detection of CNTs in human samples presented in this study is significant because: 1) CNTs were present in all randomly selected samples, and 2) the MWCNTs observed in the lungs of Parisian children are similar to those detected in dust and vehicle exhaust samples collected in the Parisian area as well as to synthetic MWCNTs (Zhu et al., 2003), to MWCNTS found in ambient air samples collected in El Paso and Houston (USA) (Murr et al., 2004; Murr and Guerrero, 2006), and those trapped in domestic spider webs in Kanpur (India) (Sonkar et al., 2009). Dusts were first collected near high-traffic roads. We observed no obvious correlation between the amounts of CNTs found in BALF samples with the distances of children\'s households from these roads: these amounts were comparable for children who lived the farthest (15km) and those who lived the closest (1.5km). Furthermore, the dusts collected near very low-traffic roads contained impressively high amounts of carbon nanoparticles quite comparable to those found near high-traffic roads. Since CNTs from anthropogenic sources may be present in indoor and outdoor air, and since air pollutants may be transported via the atmosphere, we expect that humans routinely breathe such carbon nanoparticles. While TEM has previously been used to detect carbonaceous particles inside human cells (Bunn et al., 2001), the authors only detected some carbon nano-spherules similar to those we observed. This is probably due to the fact that CNTs were not expected at the time. To the best of our knowledge, this is the first study showing that CNTs from anthropogenic sources reach human lung cells.