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[SANET-MG] nanotoxicology
http://www.i-sis.org.uk/Nanotoxicity.phpISIS Press Release 10/10/05
Nanotoxicity: A New Discipline
Dr. Mae-Wan Ho
A fully referenced version of this article is posted on ISIS members’
website. Details here
Nanoparticles – billionths of metre in dimensions - produced by
nanotechnology have unusual properties not found in the bulk material,
which can be exploited in numerous applications such as biosensing,
electronics, photovoltaics, diagnostics and drug delivery. However,
research within the past few years has turned up a range of potential
health hazards, which has given birth to the new discipline of nanotoxicity.
Researchers in the University of Texas in the United States found that
carbon nanotubes squirted into the trachea of mice caused serious
inflammation of the lungs and granulomas (tumour-like nodules of bloated
white blood cells in the lining of the lungs), and five of the nine mice
treated with the higher dose died (“Nanotubes highly toxic”, SiS 21) [1,
2].
In a similar experiment carried out at the National Institute of
Occupational Safety and Health in Morgantown, West Virginia, in the
Unites States, researchers not only found granulomas in the lungs, but
also damage to mitochondrial DNA in the heart and the aortic artery, and
substantial oxidative damage, both foreshadowing atherosclerosis
(hardening of the arteries) [3].
In yet another similar experiment in Tottori University, Japan,
researchers showed that within a minute of contacting the mice’s tiniest
airways, carbon nanotubes began to burrow through gaps between the
surface lining cells and into the blood capillaries, where the
negatively charged nanoparticles latched onto the normally positively
charged red blood cells surface, thereby potentially causing the red
blood cells to clump and the blood to clot [3].
Researchers from the University of Rochester, New York, reported an
increased susceptibility to clotting in rabbits that had inhaled carbon
nanospheres (buckyballs, an isotope of carbon shaped like a tiny
football) [3].
Buckballs present in water at 0.5 parts per million were taken up by
largemouth bass, which suffered severe brain damage 48 hours later, the
extent of damage being 17 times greater than that seen in controls [4].
Nanoparticles in the lungs are translocated to the circulatory system
and from there throughout the body, accumulating in the liver, spleen,
and bone marrow [5].
Nanoparticles inhaled through the nose and air passages are translocated
to the brain through the olfactory nerves, and accumulate in the brain [5].
Nanoparticles can enter the body through the skin; and quantum dots
injected into the skin accumulate in lymph nodes with potential effects
on the immune system [5].
Quantum dots consisting of a core of fluorescent cadmium selenide,
touted as a non-invasive way to image internal body tissues, break down
in the body, releasing cadmium, a toxic heavy metal [6].
In August 2005, the International Council on Nanotechnology (ICON) and
Rice University’s Center for Biological and environmental Nanotechnology
(CBEN) launched an online database of scientific findings related to the
risks as well as benefits of nanotechnology [7]
(http://icon.rice.edu/research.cfm). Searches using common key words
such as “quantum dots” and “nanospheres” gave zero returns in September
2005, which shows it is far from adequate and hence could well be
misleading.
The Institute of Science in Society, PO Box 32097, London NW1 OXR
telephone: [44 20 8452 2729] [44 20 7272 5636]
General Enquiries sam@i-sis.org.uk - Website/Mailing List
press-release@i-sis.org.uk - ISIS Director m.w.ho@i-sis.org.uk
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