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nanotubes

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  • tms_lz129
    Asbestos fibers are not actually tubes but tightly rolled sheets of molecules in a crystal lattice. Both the particle size and the exposed atoms at the edge
    Message 1 of 4 , Nov 6, 2007
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      Asbestos fibers are not actually tubes but tightly rolled sheets of
      molecules in a crystal lattice. Both the particle size and the
      exposed atoms at the edge of the roll probably contribute to the
      latent carcinogenicity of the materials. Carbon nanotubes are more
      likely to cause ailments related to fine dusts but those diseases only
      occur with gross exposures over long periods and this is unlikely
      except where they are being manufactured. If nanotubes ever are
      manufactured in quantity then end of life considerations will
      certainly be relevant.
    • Ariel Thomann
      Yes, neither chrysotile, crocidolite, amosite, anthophyllite, tremolite or actinolite are tubular. Nor are they carbon. Any number of chemically very
      Message 2 of 4 , Nov 7, 2007
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        Yes, neither chrysotile, crocidolite, amosite, anthophyllite, tremolite or
        actinolite are tubular. Nor are they carbon.

        Any number of chemically very different types of respirable dusts between 0.5
        and 5 microns in size have a bad habit of lodging in pulmonary alveoli (larger
        ones don't make it that far down, smaller ones are breathed back out). If they
        get trapped there, they can cause their respective pneumoconioses over the next
        several decades. Nanotubes are smaller by several orders of magnitude, so maybe
        they get exhaled -- but, does anybody KNOW that? Might they be adsorbed by the
        moisture lining the alveoli? If so, could they go through the alveaolar
        capillariy walls and be distributed throughtout the body? If so, what effect
        will they have in what organs? How long will it take before we have the answers
        to these and other questions we don't even know how to ask yet?

        Again, I'm not equating nanotubes with asbestos. All I'm saying is -- beware of
        unintended consequences.

        Ariel
        - We are all Human beings here together. We have to help one another, since
        otherwise there is NO ONE who will help.
        - All countries need a NO REGRETS strategic energy policy. Think ahead 7
        generations.
        ------------------------------------

        > Asbestos fibers are not actually tubes but tightly rolled sheets of molecules
        > in a crystal lattice. Both the particle size and the
        > exposed atoms at the edge of the roll probably contribute to the
        > latent carcinogenicity of the materials. Carbon nanotubes are more likely to
        > cause ailments related to fine dusts but those diseases only occur with gross
        > exposures over long periods and this is unlikely except where they are being
        > manufactured. If nanotubes ever are
        > manufactured in quantity then end of life considerations will
        > certainly be relevant.
      • Robert Johnston
        Ariel, This is not a new concept. It has already been discussed for several years in the nanotech scientific community as well as among regulators. I m not
        Message 3 of 4 , Nov 7, 2007
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          Ariel,

           

          This is not a new concept.  It has already been discussed for several years in the nanotech scientific community as well as among regulators.  I’m not part of that scientific community, but I read about it in Chemical & Engineering News regularly.  Many companies and universities working on nanotech have instituted strong safeguards using the precautionary principle since the hazards are not yet sufficiently known.  Rice University has done some of the work on the EH&S aspects of nanotubes.  While it is worthwhile to understand the risks, I think the leading researchers are well aware of the potential that exists.  I’m not sure it is something worth spending much time agonizing over here.  You are correct in pointing out that the hazard risk is very low once the nanoparticles or nanotubes are embedded in a matrix compound.


          Robert

           

           


          From: hreg@yahoogroups.com [mailto: hreg@yahoogroups.com ] On Behalf Of Ariel Thomann
          Sent: Wednesday, November 07, 2007 10:34 PM
          To: hreg@yahoogroups.com
          Subject: Re: [hreg] nanotubes

           

          Yes, neither chrysotile, crocidolite, amosite, anthophyllite, tremolite or
          actinolite are tubular. Nor are they carbon.

          Any number of chemically very different types of respirable dusts between 0.5
          and 5 microns in size have a bad habit of lodging in pulmonary alveoli (larger
          ones don't make it that far down, smaller ones are breathed back out). If they
          get trapped there, they can cause their respective pneumoconioses over the next
          several decades. Nanotubes are smaller by several orders of magnitude, so maybe
          they get exhaled -- but, does anybody KNOW that? Might they be adsorbed by the
          moisture lining the alveoli? If so, could they go through the alveaolar
          capillariy walls and be distributed throughtout the body? If so, what effect
          will they have in what organs? How long will it take before we have the answers
          to these and other questions we don't even know how to ask yet?

          Again, I'm not equating nanotubes with asbestos. All I'm saying is -- beware of
          unintended consequences.

          Ariel
          - We are all Human beings here together. We have to help one another, since
          otherwise there is NO ONE who will help.
          - All countries need a NO REGRETS strategic energy policy. Think ahead 7
          generations.
          ------------ --------- --------- ------

          > Asbestos fibers are not actually tubes but tightly rolled sheets of
          molecules
          > in a crystal lattice. Both the particle size and the
          > exposed atoms at the edge of the roll probably contribute to the
          > latent carcinogenicity of the materials. Carbon nanotubes are more likely
          to
          > cause ailments related to fine dusts but those diseases only occur with
          gross
          > exposures over long periods and this is unlikely except where they are
          being
          > manufactured. If nanotubes ever are
          > manufactured in quantity then end of life considerations will
          > certainly be relevant.

        • Ariel Thomann
          Robert - merci! Over and out on this topic. Ariel - We are all Human beings here together. We have to help one another, since otherwise there is NO ONE who
          Message 4 of 4 , Nov 7, 2007
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            Robert - merci! "Over and out" on this topic.

            Ariel
            - We are all Human beings here together. We have to help one another, since
            otherwise there is NO ONE who will help.
            - All countries need a NO REGRETS strategic energy policy. Think ahead 7
            generations.
            ------------------------------------

            > Ariel,
            >
            >
            >
            > This is not a new concept. It has already been discussed for several years in
            > the nanotech scientific community as well as among regulators. I'm not part
            > of that scientific community, but I read about it in Chemical & Engineering
            > News regularly. Many companies and universities working on nanotech have
            > instituted strong safeguards using the precautionary principle since the
            > hazards are not yet sufficiently known. Rice University has done some of the
            > work on the EH&S aspects of nanotubes. While it is worthwhile to understand
            > the risks, I think the leading researchers are well aware of the potential
            > that exists. I'm not sure it is something worth spending much time agonizing
            > over here. You are correct in pointing out that the hazard risk is very low
            > once the nanoparticles or nanotubes are embedded in a matrix compound.
            >
            >
            > Robert
            >
            >
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