Quantitative Analysis of the Environmental Fate of Nanoparticles Leached from Consumer Products

 

Danielle Cleveland, Stephen E. Long, Timothy M. Brewer, and Jeffrey M. Davis

 

1Analytical Chemistry Division and 2Surface and Microanalysis Science Division, Chemical Science and Technology Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899

 

 

Engineered nanomaterials have received intense attention from academia, industrial R&D, and the federal government, and have been tapped for a variety of scientific and technological applications.  Additionally, manufacturers have begun incorporating nanoparticles into hundreds of common consumer products including sunscreens, cosmetics, clothing, and toys.  Nanotechnology-based consumer products are currently entering the market at a rate of 3-4 new products per week, and it has been estimated that $2.6 trillion in manufactured goods will contain nanotechnology by 2014.  The lifecycle of a consumer product is such that it will end up in a landfill or elsewhere in the environment.  Unfortunately, the environmental fate of nanomaterials derived from consumer products is not well known, and the potential release of metallic nanoparticles from consumer goods could be detrimental to the environment, or to consumers' health.  Therefore, it is crucial to develop methods to accurately quantify and speciate nanoparticles transferred from consumer products to environmental samples. 

This project applies several approaches to study the environmental availability of gold and silver nanoparticles derived from consumer products.  Inductively coupled plasma mass spectrometry was used to measure total concentrations of gold or silver in consumer products, and the results indicated that the consumer products contained significant concentrations of gold or silver.  Electron microscopy techniques will be used in the near future to corroborate manufacturers’ claims that the products contained nanoparticles.  Temporal diffusions of ionic gold and nanoparticle gold SRMs were studied across laboratory simulated, shallow freshwater ponds.  The nanoparticle gold SRM exhibited behavior that was different than that of the ionic gold SRM, possibly indicating agglomeration of the nanoparticles in water.  Electron microscopy will be used to confirm the agglomeration status of the nanoparticles.  Unfortunately, the shallow pond studies could not account for environmental processes like trophic transfer.  Therefore, in collaboration with NOAA, these studies will be repeated in more complex estuarine mesocosms.  Initial benchtop leaching experiments confirmed that silver in the stuffing of a teddy bear could be leached from the toy into seawater in a significant amount within 3 days.  Nanoparticle speciation experiments using ion exchange resins suggested that while ionic silver was completely converted to anionic chloro species in seawater, the nanoparticles behaved differently.  It appeared that while some of the nanoparticles were converted to negative species, some remained as neutral particles.  Electron microscopy will be used to verify the presence and status of nanoparticles as a function of residence time in seawater.