Date of this Version
HHS Public Access Author manuscript Nat Nanotechnol. Author manuscript; available in PMC 2023 August 28.
Published in final edited form as: Nat Nanotechnol. 2020 March ; 15(3): 164–166. doi:10.1038/s41565-020-0656-y.
In a recent correspondence, the Swedish non-profit organization ChemSec announced the addition of carbon nanotubes to the SIN (‘Substitute It Now’) list1. Carbon nanotubes were added as an entire material class that “should be restricted or banned in the EU.” We believe that this recommendation confuses researchers and the public as it is based on evidence from a very narrow subset of data. Such a designation will likely hinder innovations that could lead to safe and effective applications of carbon nanotubes. Furthermore, this line of reasoning could damage other fields of science and technology, if applied similarly. We have worked with carbon nanotubes since the 1990s, a time marked by excitement and confusion about the promises and concerns of nanomaterials2,3. During this period, broad claims of toxicities were ascribed to carbon nanotubes, which were later found to apply only to a narrow subset of carbon nanotube preparations and/or exposure routes4,5. Numerous subsequent publications that reported more nuanced results were given much less attention6–8. Importantly, data showing a lack of toxicity are often not published, as they are usually considered ‘negative’ results9. Unfortunately, we are left with a one-sided story that damages research efforts. The recent report by the advocacy group ChemSec seems to have been confused by these issues. The REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) legislation (and the recent amendments to the Toxic Substances Control Act (TSCA) in the USA) places the burden of proof on producers and importers of chemicals to demonstrate safety. The nanotechnology field subscribes to this principle and routinely conducts tests on the biocompatibility and potential biotoxicity of nanomaterials that are under development for medical and non-medical applications. REACH registration has been attained for limited quantities of three classes of carbon nanotube materials (932-414-1, 943-098-9 and 701-160-0). The inclusion of all carbon nanotubes in the SIN list discourages research and investment in these materials that are being applied, for instance, to treat kidney disease10, track viral outbreaks11 and to investigate Parkinson’s disease12. ChemSec should take special care to not inadvertently damage a research field by generalizing narrowly-applicable findings to a diverse family of materials, and to not misapply the solid precautionary principles on which REACH and TSCA are based.