Nanosafety Research? Are We on the Right Track? Harald F. Krug claims 16 pages of the Angewandte Chemie to talk about nanotoxicology (DOI). With 10,000 papers published on the topic and not a single human casualty on record the question on nanosafety should be: YES! nanotech is safe! Move on! The main conclusions however in this review are: yes, engineered nanomaterials are safe because the human body knows how to deal with them but no, most studies carried out thus far are flawed. So if it up to Harald Krug it is not mission accomplished! but rather lets find funding for an additional 10,000 reports and do it right this time.
So how did these studies break the rules? Here are some of the findings. Materials studied were poorly defined and for example used "as purchased". Prior to testing materials were diluted in unsuitable solvents to unrealistic concentrations. According to Krug it is too easy to bury cells with a layer of nanoparticles denying it nutrients. During experimentation nanomaterials can also dissolve in the medium making the study nano non-relevant. There are some weird test-animal practises: in testing the skin barrier, skin is unrealistically stretched. In testing the lung barrier nanomaterial is injected (instilled) rather than inhaled. Other offences found in studies: lack of control samples, lack of standard operation procedures, lack of toxicological expertise.
In summary according to Krug "nanotoxicology has clearly failed to equip itself with the same fundamental rules as are applied to toxicology" and "researchers who do not know or apply these rules should no longer be given financial support for toxicologically oriented research programs."
Chemists are in general not critical of their discipline let alone about their colleagues. This lecture from an opinionated professional not sparing anyone is a refreshing read.