Title page for ETD etd-08132012-130211


Type of Document Dissertation
Author Quadros, Marina E
URN etd-08132012-130211
Title Release of Silver from Nanotechnology Consumer Products and Potential for Human Exposure
Degree PhD
Department Environmental Engineering
Advisory Committee
Advisor Name Title
Marr, Linsey C. Committee Chair
Hochella, Michael F. Jr. Committee Member
Little, John C. Committee Member
Vikesland, Peter J. Committee Member
Keywords
  • silver
  • nanosilver
  • nanoparticle
  • leaching
  • exposure
  • dissolution
  • aerosol
  • children
  • consumer products
Date of Defense 2012-08-02
Availability restricted
Abstract
Silver nanoparticles (nanosilver) are gaining significant attention from the academic and regulatory communities, not only because of their antimicrobial effects and subsequent product applications, but also because of their potential health and environmental impacts. Although some human health effects of silver nanoparticles have been reported, realistic exposure levels from the use of consumer products are still largely unknown. The objective of this work was to characterize the release of silver and silver- containing particles during the normal use of silver nanotechnology consumer products. Specific objectives were to review the environmental and human health risks of airborne, engineered nanoparticles, to characterize aerosol emissions from nanosilver spray products, and to characterize nanosilver that may be released from childrenʼs consumer products under conditions of normal use. We identified possible routes of aerosolization of nanosilver from the production, use, and disposal of consumer products and estimated that about 14% of silver nanotechnology products that have been inventoried could potentially release silver particles into the air during use. The spray products investigated emitted 0.24 – 56 ng of silver in aerosols per spray action, and the plurality of aerosols were 1 – 2.5 μm in diameter, easily inhaled, for two products. Both the productsʼ liquid characteristics and the bottlesʼ spraying mechanisms played roles in determining the aerosol size distributions, but the size of silver-containing aerosols was largely independent of the liquid phase size distributions. We compiled an inventory of 82 children's consumer products that claim to contain nanosilver, of which 13 products were examined for presence of silver and tested for release of silver into liquid media and air, and onto skin. All products contained some form of silver, but silver-containing particles were observed in only four products, with sizes ranging from nanoscale up to 10 μm in size. Silver leached preferably into synthetic biological media with higher chloride concentrations, such as sweat and urine. We determined that levels of silver to which children would be exposed during normal use of these products are likely to be low, and bioavailable silver is expected to be in ionic rather than particulate form.
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