On April 7, 2020, the European Union (EU) Observatory for Nanomaterials (EUON) published a Nanopinion entitled “Carbon Nanotubes — First nanomaterial of high concern on the SIN List.”  As reported in our November 27, 2019, blog item, ChemSec added carbon nanotubes to the Substitute It Now (SIN) List in November 2019.  According to Dr. Anna Lennquist, Senior Toxicologist, International Chemical Secretariat (ChemSec), ever since ChemSec created the SIN List, there have been requests to add nanomaterials to the List.  Lennquist states that several studies of different types of multi-walled carbon nanotubes show carcinogenicity for lungs, and the International Agency for Research on Cancer (IARC) classified one type as “possibly carcinogenic to humans” in summer 2019. 

Genotoxicity and lung damage have been shown by more types of carbon nanotubes, including single-walled, double-walled, and multi-walled.  According to Lennquist, “[t]he persistence of carbon nanotubes under realistic conditions has been proven,” and, for single-walled carbon nanotubes, “there is evidence of reprotoxic effects.”  Lennquist acknowledges that there were “many discussions internally, as well as with experts, before deciding to place all carbon nanotubes as one entry on the SIN List.”  ChemSec chose a single entry for practical, political, and scientific reasons:  consumer products often consist of several types of carbon nanotubes; ChemSec is “striving politically towards a more groupwise regulation of chemicals,” and “scientifically we could not justify where to draw a line between hazardous and less hazardous carbon nanotubes.” 

Lennquist states that with the addition of carbon nanotubes to the SIN List, “we want to show that nanoforms can and should be evaluated as any other chemical substance.  Not all nanomaterials are safe, not all are hazardous, but it must be a case-by-case assessment.”