Are Multi-Walled Carbon Nanotubes More Like Asbestos Than We Thought?

John BalbusJohn Balbus, M.D., M.P.H., is Chief Health Scientist.

We and many others have made analogies between nanoparticles and asbestos.  The purpose of the analogy has generally been to emphasize the long latency that can occur between exposure to toxic materials and the development and subsequent recognition of disease arising from that exposure.  And, of course, the enormous legal and financial burden of failing to adequately consider risks before allowing widespread exposure.  But a new study suggests that the analogy may be even stronger than we thought:  It may extend to the capacity to cause mesothelioma, the rare form of cancer associated with exposure to asbestos.

In a recent study published in the Journal of Toxicological Sciences, researchers at Japan’s National Institute of Health Sciences injected commercial multi-walled carbon nanotubes (MWCNTs) into the peritoneal cavities of mice that were bred to be especially susceptible to mesothelioma.  (The peritoneal cavity is the space between the abdominal organs and abdominal wall that is lined with mesothelial cells, which can give rise to mesotheliomas).

They compared the mice’s response to injected MWCNTs to the response to crocidolite asbestos (the form of asbestos most strongly associated with mesothelioma), and also to fullerenes.  They found that the potency of MWCNTs in causing mesotheliomas in these mice was at least as high as the asbestos.  In contrast, fullerenes did not cause any mesotheliomas.

The physicochemical characteristics of MWCNTs are similar in many ways to asbestos.  Both are rigid, rod-like shapes with a high length to width (aspect) ratio and lengths that can extend to 5 microns or longer. Both are biopersistent and contain iron.  Given that all of these characteristics collectively contribute to the carcinogenicity of asbestos, this study suggests these same characteristics may cause MWCNTs to be carcinogenic as well.

This study doesn’t prove that inhaling MWCNTs causes mesothelioma; it would first have to be shown that inhaled MWCNTs can make their way through the lung to contact mesothelial cells, and then persist there long enough to initiate carcinogenesis in less susceptible animals.  Asbestos does this, of course, and there’s no obvious reason why MWCNTs should behave differently.  More pieces of the puzzle need to be filled to demonstrate the actual degree of risk, but this is clearly a large red flag.

Because MWCNTs, unlike asbestos, are deliberately engineered, it’s possible that characteristics like iron content and fiber length may be controlled to render the tubes less or even non-carcinogenic.  But with the wide variations noted for single-walled carbon nanotubes (see our earlier post), manufacturers of MWCNTs would have to demonstrate the ability to manufacture product consistently to specifications, and users of MWCNTs would need to be wary of variations from producer to producer.  In the meantime, researchers developing and using MWCNTs, especially for applications that could yield long-term exposures, such as incorporation into hip prostheses, need to proceed with extreme caution and carefully assess the potential for carcinogenicity from their devices.

This entry was posted in Emerging Science, Health Science, Nanotechnology and tagged , , . Bookmark the permalink. Both comments and trackbacks are currently closed.

3 Comments

  1. mary slattey
    Posted May 4, 2008 at 6:27 am | Permalink

    I would like to email Dr. Balbus; we are looking for a solid accurate assessment of potential health effects of building a refinery in Union County SD. The proposed site would be 50 feet above the Missouri River aquifer; and of course be surrounded by crops, two schools withing 10 miles. This is a 400000 gallon per day refinery. There will be a vote this month by the county. Clearly childhood ashma, luekemia and possibly lymphomas have been tied to living near a refinery. Suface water contamination is a concern because of the Missouri River.

  2. Edwin Clarke
    Posted May 25, 2008 at 1:14 am | Permalink

    Many people are feel scared of de nanons.

  3. Posted April 22, 2009 at 6:43 am | Permalink

    nice post , many accident asbetos have a bad effect for life. but you have good advice through this blog.

  • About this blog

    Science, health, and business experts at Environmental Defense Fund comment on chemical and nanotechnology issues of the day.

    Our work: Chemicals

  • Categories

  • Get blog posts by email

    Subscribe via RSS

  • Filter posts by tags

    • aggregate exposure (9)
    • Alternatives assessment (3)
    • American Chemistry Council (ACC) (53)
    • arsenic (3)
    • asthma (3)
    • Australia (1)
    • biomonitoring (9)
    • bipartisan (6)
    • bisphenol A (18)
    • BP Oil Disaster (18)
    • California (1)
    • Canada (7)
    • carbon nanotubes (24)
    • carcinogen (21)
    • Carcinogenic Mutagenic or Toxic for Reproduction (CMR) (12)
    • CDC (6)
    • Chemical Assessment and Management Program (ChAMP) (13)
    • chemical identity (30)
    • chemical testing (1)
    • Chemicals in Commerce Act (3)
    • Chicago Tribune (6)
    • children's safety (22)
    • China (10)
    • computational toxicology (10)
    • Confidential Business Information (CBI) (51)
    • conflict of interest (4)
    • consumer products (48)
    • Consumer Specialty Products Association (CSPA) (4)
    • contamination (4)
    • cumulative exposure (4)
    • data requirements (45)
    • diabetes (4)
    • DNA methylation (4)
    • DuPont (11)
    • endocrine disruption (28)
    • epigenetics (4)
    • exposure and hazard (49)
    • FDA (8)
    • flame retardants (20)
    • formaldehyde (14)
    • front group (13)
    • general interest (20)
    • Globally Harmonized System (GHS) (5)
    • Government Accountability Office (5)
    • hazard (6)
    • High Production Volume (HPV) (22)
    • in vitro (14)
    • in vivo (11)
    • industry tactics (40)
    • informed substitution (1)
    • inhalation (18)
    • IUR/CDR (27)
    • Japan (3)
    • lead (6)
    • markets (1)
    • mercury (4)
    • methylmercury (2)
    • microbiome (3)
    • nanosilver (6)
    • National Academy of Sciences (NAS) (18)
    • National Institute for Occupational Safety and Health (NIOSH) (7)
    • National Institute of Environmental Health Sciences (NIEHS) (5)
    • National Nanotechnology Initiative (NNI) (6)
    • obesity (6)
    • Occupational Safety and Health Administration (OSHA) (3)
    • Office of Information and Regulatory Affairs (OIRA) (4)
    • Office of Management and Budget (OMB) (15)
    • Office of Pollution Prevention and Toxics (OPPT) (3)
    • oil dispersant (18)
    • PBDEs (16)
    • Persistent Bioaccumulative and Toxic (PBT) (22)
    • pesticides (7)
    • phthalates (16)
    • polycyclic aromatic hydrocarbons (PAH) (5)
    • prenatal (6)
    • prioritization (35)
    • risk assessment (68)
    • Safe Chemicals Act (24)
    • Safer Chemicals Healthy Families (33)
    • Significant New Use Rule (SNUR) (19)
    • Small business (1)
    • South Korea (4)
    • styrene (5)
    • Substances of Very High Concern (SVHC) (15)
    • systematic review (1)
    • test rule (16)
    • tributyltin (3)
    • trichloroethylene (TCE) (3)
    • Turkey (3)
    • U.S. states (14)
    • vulnerable populations (1)
    • Walmart (2)
    • worker safety (21)
    • WV chemical spill (11)
  • Archives