A review of exposure and toxicological aspects of carbon nanotubes, and as additives to fire retardants in polymers

ABSTRACT

Carbon nanotubes (CNTs) have attracted considerable interest due to their unique physical, chemical, optical and electrical properties opening avenues for a large number of industrial applications. They have shown potential as fire retardant additives in polymers, reducing heat release rate and increasing time to ignition in a number of polymers. Relevant work on the types, properties and applications has been reviewed particularly considering their application in fire situations. There are concerns over the health risks associated with CNTs and many papers have likened CNTs to the health problems associated with asbestos. There are contradictions relating to the toxicity of CNTs with some papers reporting that they are toxic while others state the opposite. Directly comparing various studies is difficult because CNTs come in many combinations of size, type, purity levels and source. CNTs can potentially be released from polymers during the combustion process where human exposure may occur. While this review has shed some light regarding issues relating to toxicity under different fire scenarios much more thorough work is needed to investigate toxicity of CNTs and their evolution from CNT–polymer nanocomposites in order to reach firm conclusions.

Keywords:

• carbon nanotubes
• nanotoxicology
• nanoparticle release
• fire retardants

Acknowledgements

We would like to thank the reviewers selected by the editor for their time and their excellent suggestions and advice for completing this review.

Declaration of interest

The authors affiliations are as shown on the first page of the article. This work is funded by the European Union’s Seventh Framework Programme FP7/2007-2013 under grant agreement (no 308391; DEROCA). The conduct of the review, the synthesis and interpretation of the literature and the conclusions drawn are exclusively those of the authors.