But… Nanotechnology, is it toxic or not?
During last Nanotoes meeting the following question was rised: how to communicate nanotoxicology to society? It is very likely that PhD students being trained as experts on nanosafety may be asked, maybe too early. Additionally, they may be asked to explain it in two minutes, if nanoparticles are toxic or not.
Trying to contribute to ease the students from such annoying situation, I was thinking in what could be acceptable arguments for such an over-simplistic question. For that, the simplest answer would be that we are really working hard on it and that the supervisors really look bright, careful and compromised. Also one could just answer that Nanotechnology or even Nanoparticles is too large to fit inside a question. Are bacteria bad? How to feed ourselves without? In the nanorealm one ranks toxic things as blue asbestos, and safe things, as milk fatty particles, viruses and proteins. A diverting answer is to tell them that we are the canary in the coal mine. An old pre-technology sensor of firedamp (a flammable gas found in coal mines, especially methane, but also carbon dioxide and monoxide) in the coal mine. In the presence of methane or carbon monoxide, or the absence of oxygen canary was the first to fall indicating the toxic composition of air. Additionally, despite the finding of nanoparticles every remote place on earth, we have not yet produced enough nanoparticles to pollute the world, other than those pre-nanotehcnology coming from fuel burning. Far from that, it is a question of amount. Even the most used ones, as TiO2, are produced in relatively small quantities when compared to many other things we pour around us. But we, in the labs, are in close contact with it voluntarily, this is why we are the canaries, although they were not there voluntarily but caged. Additionally, we are really concerned about any deleterious and unwanted side effect that may posses. One could also say that nanoparticles where here before us and before we find them out. Even used by biology, as the magnetosomes in magnetotactic ancient bacteria, where 15-20 iron oxide and iron sulphide exquisite nanoparticles are synthesized and used as a compass to determine oxygen concentration in water. Burning a candle produces carbon nanotubes. The colour of the glasses in the old churches were already made up from oxide nanoparticles. People like this kind of stories. One should understand the importance of context (this is why the title question is so poor), medical applications under specialists surveillance is very different from making gorgeous glow-in-the-dark soap bubbles loaded of CdSe that will Cd-poison the audience as the bubbles collapse over they surprise-open mouths. A scalpel is very dangerous. Also electricity.
It may be important to say that initial testing did not found a special unexpected toxicity of nanoparticles beyond expectable predictions from well documented toxicology, with special mention of asbestosis and air pollution toxicology and metal poisoning. Off course laws of physics where confirmed with the baguette and the piano effects. In the first, a mice suffocated after instillation of a massive amount of hydrophobic CNTs in its trachea. The conclusion was that hydrophobic things do not disperse well in living bodies. The analogy would be that a French baguette is not toxic but inserted in the trachea may pose real challenges for respiration. Similarly, a piano is not toxic unless it fells on top of you from above. As when NPs are unstable and aggregate forming microparticles larger than cells themselves burying them. Or reverse, the colour of the particles masking the colour signals coming from cells hided the hundred per cent toxicity in in vitro tests. All this accumulated knowledge and new to come will in principle open a window of opportunity for the safe and responsible use of nanotechnology. Now we face the difficult task to determine subtle -but critical- effects that escape the initial screening performed mainly in models relatively close to real cases, or prolonged exposure studies (accumulation, memory…) or long term unwanted effects. I also think that we are still in time of propose ways to use nanoparticles safely, first in a few cases that will help us to categorize risk of nanoparticles in a more extense way. Finally, to journalists and the general public, I would also requiere their committment to make an effort and understand what is nanotechnology and nanoparticles, so they, so curious and concerned, can meaningfully participate in the open governance of nanotechnologies in society.