9/15/10
Exposure of nanomaterals
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Nanoparticles in various forms are now incorporated in more than 1000 commercial products including textiles, conductive inks, solar cells, personal care products, medical devices, cosmetics, appliances, and baby products. This creates a situation that users will be in contact with nanomaterials someway on a frequent and long-term basis during their day to day activities. While the benefits of nanomaterials have been well recognized, there is concern that some nanotechnology enabled products may pose a risk to the environment and human health at some point in their life cycle. Some researchers also suggest that nanomaterials are potentially more toxic and dangerous than their bulk counterparts. Hence it is important to predict and measure the health impacts and environmental implications of nanomaterials.Apart while using nanotechnology enabled products, exposure to nano materials takes place at production and processing level. The ways of primary exposure of nanomaterials is through aerosolization and inhalation. Aerosolization can occur during synthesis, production, handling and processing of nanomaterials at the level of manufacturing stage.
When drying nanoparticle suspensions for the development of nano composits, the process can maximize the aerosolizability of the material. Exposure through inhalation can occur when dealing with powdered materials. For example, spray drying of nanoparticles for coatings, production of powdered materials, and the preparation of nano composite materials could result in exposure to nanoparticles through inhalation.
In the industrial production, a custom aerosol chamber is used. This chamber is equipped with pneumatic, venturi, and burst disk launch mechanisms that disseminate nanomaterials with different shear forces and creates nanoparticle clouds with various densities, average sizes, and aggregation levels. Quantification of the potential exposure risk and hazard of handling different types of nanomaterials is done by instrumenting and monitoring in real-time basis the particle counts, size distributions of aerosolized particles and aggregates in the size regime of 5-15,000 nm, identifying mass loadings, and measuring the optical properties like absorption, scattering, and extinction at wavelengths from400 nm to 20 microns.
Further while under long storage, the nanomaterials are batched and monitored with time to ensure that storage has not altered their properties. Materials of interest include various forms of carbon like C60, nanotubes, graphite, etc. other metals like copper, manganese, iron, palladium, etc.,metal oxides like TiO2, Fe2O3, CeO2, ZrO, etc., ceramics, and semiconductor nanoparticles. Tools utilized to understand changes to the surface of the nanoparticles include isoelectric point, matrix aided laser desorption ionization mass spectrometer (MALDI-MS), Fourier Transform Infrared Spectroscopy (FTIR), and Raman spectroscopy.
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