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148. Carbon Nanotubes

Hedmer, Maria LU ; Kåredal, Monica LU ; Gustavsson, Per LU and Rissler, Jenny LU (2013) In Arbete och Hälsa 148.
Abstract
Carbon nanotubes (CNTs) can be seen as graphene sheets rolled to form cylinders. CNTs may be categorised as single- (SWCNT) or multi-walled (MWCNT). Due to the small size, the number of particles as well as the surface area per mass unit is extremely high. CNTs are highly diverse, differing with respect to e.g., diameter, length, chiral angles, chemical functionalisation, purity, stiffness and bulk density. Today, CNTs are utilised primarily for the reinforcement of composite polymers, but there is considerable potential for other applications. The rapidly growing production and use of CNTs increases the risk for occupational exposure. Since CNTs in bulk form are of very low density and much dust is produced during their handling, exposure... (More)
Carbon nanotubes (CNTs) can be seen as graphene sheets rolled to form cylinders. CNTs may be categorised as single- (SWCNT) or multi-walled (MWCNT). Due to the small size, the number of particles as well as the surface area per mass unit is extremely high. CNTs are highly diverse, differing with respect to e.g., diameter, length, chiral angles, chemical functionalisation, purity, stiffness and bulk density. Today, CNTs are utilised primarily for the reinforcement of composite polymers, but there is considerable potential for other applications. The rapidly growing production and use of CNTs increases the risk for occupational exposure. Since CNTs in bulk form are of very low density and much dust is produced during their handling, exposure by inhalation appears to represent the greatest potential risk in the work place. However, most work place measurements involved sampling periods that

are too short, varying sampling techniques and non-specific analytical methods. CNTs may be absorbed via inhalation and ingestion. Systemic uptake via the skin has not been demonstrated. Human toxicity data on CNTs are lacking and interpretation of animal studies is often problematic since the physical properties and chemical composition are diverse, impurities may be present and data are sometimes omitted. Because of the physical similarities between asbestos and CNTs, it can be suspected that the latter may also cause lung fibrosis, mesothelioma and lung cancer following inhalation. Intraperitoneal and intrascrotal administration of CNTs causes mesothelioma in animals, but no inhalation carcinogenicity studies have been conducted. Thus, it is too early conclude whether CNTs cause mesothelioma and lung cancer in humans. Both SWCNTs and MWCNTs cause inflammation and fibrosis in the lungs of relevant animal types and for MWCNTs these effects are also seen in the pleura. For instance, minimal histiocytosis and mild granulomatous inflammation in the

lungs and lung-draining lymph nodes have been observed in rats exposed for 13 weeks to 0.1 mg/m3 MWCNTs (lowest observed adverse effect level, LOAEL), with more pronounced inflammation in both mice and rats at higher doses. Thus, inflammatory responses in the lungs may be considered as the critical effect. However, the LOAEL of CNTs should be interpreted cautiously, since their toxicity is likely to vary widely, depending on the structure and physicochemical properties, as well as the contribution from non-carbon components. It is also uncertain which dose metric (e.g., mass, number or surface area per air volume unit) is most appropriate. Some studies indicate that longer straight CNTs evoke more pronounced

biological effects than shorter or tangled fibres. (Less)
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author
organization
publishing date
type
Book/Report
publication status
published
subject
keywords
carbon nanotubes, CNTs, fibrosis, inflammation, lung effects, occupational exposure limit, review, risk assessment, toxicity
in
Arbete och Hälsa
volume
148
pages
238 pages
publisher
The Nordic Expert Group for Criteria Documentation of Health Risks from Chemicals
ISBN
978-91-85971-46-6
language
English
LU publication?
yes
id
d58cd149-1125-4050-b49a-dae7f382ba5f (old id 4249065)
date added to LUP
2014-02-12 10:13:58
date last changed
2016-04-16 08:17:52
@techreport{d58cd149-1125-4050-b49a-dae7f382ba5f,
  abstract     = {Carbon nanotubes (CNTs) can be seen as graphene sheets rolled to form cylinders. CNTs may be categorised as single- (SWCNT) or multi-walled (MWCNT). Due to the small size, the number of particles as well as the surface area per mass unit is extremely high. CNTs are highly diverse, differing with respect to e.g., diameter, length, chiral angles, chemical functionalisation, purity, stiffness and bulk density. Today, CNTs are utilised primarily for the reinforcement of composite polymers, but there is considerable potential for other applications. The rapidly growing production and use of CNTs increases the risk for occupational exposure. Since CNTs in bulk form are of very low density and much dust is produced during their handling, exposure by inhalation appears to represent the greatest potential risk in the work place. However, most work place measurements involved sampling periods that<br/><br>
are too short, varying sampling techniques and non-specific analytical methods. CNTs may be absorbed via inhalation and ingestion. Systemic uptake via the skin has not been demonstrated. Human toxicity data on CNTs are lacking and interpretation of animal studies is often problematic since the physical properties and chemical composition are diverse, impurities may be present and data are sometimes omitted. Because of the physical similarities between asbestos and CNTs, it can be suspected that the latter may also cause lung fibrosis, mesothelioma and lung cancer following inhalation. Intraperitoneal and intrascrotal administration of CNTs causes mesothelioma in animals, but no inhalation carcinogenicity studies have been conducted. Thus, it is too early conclude whether CNTs cause mesothelioma and lung cancer in humans. Both SWCNTs and MWCNTs cause inflammation and fibrosis in the lungs of relevant animal types and for MWCNTs these effects are also seen in the pleura. For instance, minimal histiocytosis and mild granulomatous inflammation in the<br/><br>
lungs and lung-draining lymph nodes have been observed in rats exposed for 13 weeks to 0.1 mg/m3 MWCNTs (lowest observed adverse effect level, LOAEL), with more pronounced inflammation in both mice and rats at higher doses. Thus, inflammatory responses in the lungs may be considered as the critical effect. However, the LOAEL of CNTs should be interpreted cautiously, since their toxicity is likely to vary widely, depending on the structure and physicochemical properties, as well as the contribution from non-carbon components. It is also uncertain which dose metric (e.g., mass, number or surface area per air volume unit) is most appropriate. Some studies indicate that longer straight CNTs evoke more pronounced<br/><br>
biological effects than shorter or tangled fibres.},
  author       = {Hedmer, Maria and Kåredal, Monica and Gustavsson, Per and Rissler, Jenny},
  institution  = {The Nordic Expert Group for Criteria Documentation of Health Risks from Chemicals},
  isbn         = {978-91-85971-46-6},
  keyword      = {carbon nanotubes,CNTs,fibrosis,inflammation,lung effects,occupational exposure limit,review,risk assessment,toxicity},
  language     = {eng},
  pages        = {238},
  series       = {Arbete och Hälsa},
  title        = {148. Carbon Nanotubes},
  volume       = {148},
  year         = {2013},
}