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Just How Toxic Are Carbon Nanotubes?
11/29/2012

Researchers at Texas Tech University have come up with a new method for detecting CNTs in soils, which will help determine their toxicity. CNTs are so small that mean outer diameters of 13nm to 16nm are common in multi-walled tubes, shown here as grains partially smeared on paper (scale in centimeters).   (Source: Shaddack/Wikimedia Commons)
Researchers at Texas Tech University have come up with a new method for detecting CNTs in soils, which will help determine their toxicity. CNTs are so small that mean outer diameters of 13nm to 16nm are common in multi-walled tubes, shown here as grains partially smeared on paper (scale in centimeters).
(Source: Shaddack/Wikimedia Commons)

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sbkenn
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Re: Toxic? carbon nanotubes
sbkenn   12/1/2012 1:29:19 PM
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I believe that CNN's do occur naturally, as in Damascus Steel of the Medieval to mid 1800's, when the iron ore mines(thought to have been in Kerala in India) were cleaned out.

William K.
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Carbon nanotubes
William K.   12/1/2012 3:56:12 PM
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Damascus steel is certainly some impressive stuff, but my understanding is that it is created through a great deal of work, bonding and folding and rebonding to get steel with alternating layers of hard and tough steel. Definitely not a naturally occurring material. Free lead, nickle, cadmium, and copper all occur in their free state and can be found naturally. Likewise asbestos, although it is usually in with mica, I think.

Of course heating to ignition with microwaves would be an effective means of disposal for CNT waste, but first it would need to be located. That is probably going to be the challenge if quantities of CNT material are spilled.

etmax
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Re: Toxic? carbon nanotubes
etmax   12/2/2012 10:36:25 PM
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Are you sure it was carbon in Damascus steel?? I thought it was cobalt or something like that?

Ann R. Thryft
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Re: life cycle concerns
Ann R. Thryft   12/3/2012 11:56:44 AM
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Lou, thanks for your comments. Researching and writing this article made me think how, for the nth time, we've gone off looking for new technologies without first considering whether the (new or old) materials involved are harmful to living beings when introduced into the ecosystem, or even how likely it is that the materials can easily get into the ecosystem. It's simply not one of the first questions we ask--and I think it should be.

Dave Palmer
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Re: Toxic? carbon nanotubes
Dave Palmer   12/3/2012 2:35:47 PM
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A German research group published an article in Nature in 2006 showing that a Damascus blade produced in the 17th century contained multi-walled carbon nanotubes, as well as cementite nanowires.  It's believed that the nanotubes formed in-situ during the forging process.  You can read the article here.

The article mentions that cobalt, along with other alloying elements present in small amounts, played an important role in providing the steel with its distinctive microstructure.

Dave Palmer
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Re: life cycle concerns
Dave Palmer   12/3/2012 2:41:32 PM
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@Ann: You're definitely right that environmental and health impacts should be at the front of our minds when evaluating a new material.  That being said, there has been a lot of work done on the toxicity of nanomaterials, particularly over the past 5-7 years. A lot of people are working on this, to ensure that we aren't opening Pandora's box.

Ann R. Thryft
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Re: life cycle concerns
Ann R. Thryft   12/3/2012 3:01:30 PM
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Tim and ervin0072002, based on the Japanese, US and European concerns about CNTs from all sources, which we covered here
http://www.designnews.com/document.asp?doc_id=237995
and especially during the manufacturing process, I think the answer to Tim's question is "yes."

Cabe Atwell
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Re: life cycle concerns
Cabe Atwell   12/3/2012 4:38:16 PM
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Great, one of the future super-materials is poised to kill us all. I suppose silicon has been killing life for decades directly and indirectly. What else is new. Perhaps the study should look at how the nano-tube compares to the material it is replacing. I'm sure as materials like this become commercialized, they will.

C

Dave Palmer
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Re: life cycle concerns
Dave Palmer   12/4/2012 10:43:19 AM
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@Cabe: Obviously everything has risks, but it's important to understand the risks, so that you can keep them under control.  There are three Superfund sites within walking distance of my house.  One is a former Johns Manville insulation plant that once employed 6500 people. It is still contaminated with more than 3 million cubic yards of asbestos.  Another is our harbor, which is contaminated with PCBs that were used in a former die casting facility that employed more than 4000 people.  Not only are the jobs gone, but we're left with the mess and its long-term effects.  This is why it's important to understand the health and environmental implications of a material before employing it on a mass scale.



Ann R. Thryft
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Re: life cycle concerns
Ann R. Thryft   12/4/2012 11:48:39 AM
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Dave, thanks for the info and links, and the perspective of one directly affected by environmental toxicity. Cabe, the toxicity potential is far, far worse with nanomaterials than with materials that have micro-sized particles, such as silicon. It's a matter of scale, for one thing: in this case, size matters enormously (pun intended). You might want to take a look at some of the background material, such as the links Dave provided or those in my previous nanomaterial legislation article, to understand how different events at the nanoscale can be from events at the microscale. It's an eye-opener.

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