Evidences of copper nanoparticle exposure in indoor environments: Long-term assessment, high-resolution field emission scanning electron microscopy evaluation, in silico respiratory dosimetry study and possible health implications.

A variety of appliances operated by brush electric motors, widely used in indoor environments, emit nanoparticles (NPs). Due to electric arc discharge during the operation of such motors, some NPs contain copper (Cu). Their dimensions are the same of those found in brain tissue samples by other authors who speculated their possible translocation to brain through olfactory bulb. Cu has been reported to play an important role in the etiopathogenesis of Alzheimer's disease. Thus, the present study was performed to 1. estimate by means of Multiple-Path Particle Dosimetry model the doses of NPs released by electric appliances that can potentially deposit on the olfactory bulb; 2. investigate the morphology and the composition of particles emitted by some electric appliances daily used in indoor environments; 3. monitor for a long time period the Cu contamination of indoor environments due to this kind of appliances. About 106-107 NPs deposit on the olfactory bulb during the operation (1.5-6 min) of such appliances, with a major contribution due to 10-20 nm NPs. HR-FESEM characterization confirmed the presence of such NPs, that were observed both as individual particles (20-40 nm) and aggregated to form particles in the μm sizes range. XEDS microanalysis revealed the presence of Cu together with other elements. Relevant daily contamination of indoor environments due to these appliances has been confirmed by monitoring throughout a year the Cu content of PM10 samples collected both indoor and outdoor private dwellings. Cu was present in great part as an insoluble form. This means that, following protracted exposure, Cu NPs of such origin may undergo tissue accumulation. This is cause of concern because general population is chronically exposed to such Cu nanoparticles in indoor environments and in view of the role assigned to Cu in the development of neurological disorders.