Does the Effect of Nanoparticles on Amino Acids Translate into a Risk for Consumers?

I am sure for the next few days—if not weeks and even years—research out of Trinity College Dublin will be portrayed in the press and among some NGOs as "nanotechnology causes arthritis."

Unfortunately, the story of the research—which was published in the journal Nanomedicine— is a bit more complicated than that and the details will likely get lost in the furor that the initial headlines will generate. Basically, the researchers examined whether proteins when exposed to certain nanoparticles can change the amino acid arginine into the amino acid citrulline. This process known as post-translational citrullination of proteins has been linked to autoimmune diseases like rheumatoid arthritis.

So maybe to avoid some confusion, it might be best to say from the outset that this research does not establish the risk of nanoparticles but only their potential hazard under very controlled (but unusual) circumstances. Further, despite what the press release may claim, I don’t see how they have established much in the way of safety implications for the “use and ultimate disposal of nanotechnology products and materials.”

Whenever I see a story about nanoparticles and toxicity, I immediately drag out my formula for understanding risk: Hazard x Exposure = Risk. When you consider that the researchers did not expose human cells from the lining of the airway passages to a freshly minted carbon nanotube bicycle, you start to wonder how they have established that “nanotechnology products” are a threat to our safety. They have established that some free-floating nanoparticles effect a change in proteins, but— apart from the pollution we have been exposed to since automobiles  with carbon black tires first started driving on pavement— how often are we exposed to free-floating nanoparticles or deliberately manufactured nanoparticles like carbon nanotubes?

For me this raises the more vexing concern of when we’ll eventually see more research on how long it would take for the carbon nanotubes to be released from the material matrix of a “nanotechnology product”—like a carbon fiber bicycle—so that they could cause the kind of hazard the researchers from Trinity College have described.

While a carbon nanotube or some other nanoparticles “facilitating post-translational citrullination of proteins” is no doubt a serious concern, it sort of pales in comparison to say hydrofluoric acid, which on its own can kill you depending on your exposure but as an ingredient among others can formulate the drug Prozac. Go figure.  Again, what we need to start seeing more of in nanoparticle toxicology research is how dangerous those particles are when they are part of a larger material matrix.

Increasingly research is showing what the Royal Society warned about nearly 10 years ago in their report “Nanoscience and nanotechnologies: opportunities and uncertainties”: Workers making products out of nanoparticles are in more danger than those who buy and use the products made from the nanoparticles. But lifecycle risks from these products  have to be more aggressively pursued so that we can take appropriate precautions  while still enjoying all the benefits these nanoparticles can impart.




Dexter Johnson
Madrid, Spain
Rachel Courtland
Associate Editor, IEEE Spectrum
New York, NY