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Your Environment. Your Health.

Final Progress Reports: Brown University: Mechanisms of Hg Adsorption and Metals Exposure from Mixed Pollutant Streams

Superfund Research Program

Mechanisms of Hg Adsorption and Metals Exposure from Mixed Pollutant Streams

Project Leader: Robert H. Hurt
Grant Number: P42ES013660
Funding Period: 2005-2009

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Final Progress Reports

Year:   2008 

The  Mechanisms Of Hg Adsorption From Mixed Pollutant Streams project addresses both the applications and implications of new nanomaterials for human health and the environment.  In 2008 Dr. Robert Hurt and his research team continued their work on characterizing mercury vapor release from broken fluorescent lamps, they developed a new nano-selenium reactive barrier concept for capturing mercury vapor and avoiding human exposures, and continued their work to understand the origin of adverse health impacts from carbon nanotubes and to reduce nanotube health risks through new detoxification strategies. 

This year the team completed a publication on the release patterns and capture of mercury in fluorescent lamps and submitted to Environmental Science and Technology in January 2008.  The publication, “Release of Mercury from Broken Compact Fluorescent Lamps and Capture with New Nanomaterial Sorbents”, appeared in ES&T in July 2008 and was covered widely in the popular and scientific press including a feature article in Nature Nanotechnology ("Nano-Selenium Captures Mercury" Sept. 2008), Chemical and Engineering News (“Compact Bulbs Made Safer, July 2008), and Environmental Health Perspectives ("Mercury – Cleanup for Broken CFLs", Sept. 2008).   Two provisional patent applications were filed in 2008 and discussions held over the course of summer and fall with environmental and venture capital firms about commercialization potential.  The research continued in 2008, focused on the further development and scientific understanding of the most powerful sorbent identified in that study, uncoated, amorphous nano-selenium.   A new reactive barrier approach was designed and tested for suppressing mercury release in three scenarios: (i) break sites on porous substrates such as carpets, (ii) disposal/recycle bags, (iii) boxes used for collection and/or shipping in retail and recycle programs.  Nano-selenium barriers represent a promising control strategy to reduce human exposure to mercury in these scenarios and work will continue on this topic in 2009.

The researchers’ second major focus was on understanding carbon nanotube toxicity mechanisms and developing materials science approaches to safe formulation.  This work was done in close collaboration with Agnes Kane (Genotoxic Potential Of Mixed Dust Exposures project).  Early studies have shown a variable biological response to nanotube exposure, and the team hypothesizes that this variability is due in part to real differences in the materials, including the amount and nature of transition metal catalyst residues, length, biopersistence, and surface chemistry.  The work on nanotube metals effects produced two publications in 2007 on the bioavailability of iron (Guo et al., 2007) and nickel (Liu et al, 2007).  In 2008 the team hypothesized that the presence of bioavailable metal in many nanotubes was due to flaws in commercial purification processes, and they tested that hypothesis by understanding the forms of bioavailable metal and developing alternative purification processes that specifically target that fraction of the total metal.  A publication on this topic ("Targeted Removal of Bioavailable Metal as a Detoxification Strategy for Carbon Nanotubes") was published in Carbon in 2008.  Also submitted was an article on the interesting finding that carbon nanotubes can adsorb folic acid and certain other micronutrients from cell culture medium and influence cell proliferation by nutrient depletion without the necessity for direct cell/nanotube contact.  This work was completed and appeared in the nanotechnology journal Small in 2008.  Dr. Hurt’s team also worked with Agnes Kane on a "News and Views" article for Nature Nanotechnology addressing the recent reports of asbestos-like pathogenicity for nanotubes, entitled "Nanotoxicology: the Asbestos Analogy Revised" (July 2008). 

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