Here’s another study to add to the list of potential (or probable) problems with a world exposed to nanoparticles: Nanomedicine [12 June 2012, paywalled, Citrullination of proteins: a common post-transitional modification pathway induced by different nanoparticles in vitro and in vivo]. Translated: Many kinds of nanoparticles (billionths of a meter in size) can find their way into the cells of the immune system and may induce autoimmune processes such as rheumatoid arthritis.

Research on human and mice cells by Trinity College (Dublin, Ireland) and the Health Effects Laboratory Division of the National Institute for Occupational Safety and Health (Morgantown, Wyoming, USA) has shown that a variety of nanoparticles (carbon black, carbon nanotubes, silicon dioxide) entering through the lungs, find their way into cells of the immune system (phagocytic cells) and cause a transformation of an amino acid, arginine, into a molecule called citrulline. Transformed cells no longer function properly and are then attacked and removed by other cells of the body’s immune system. This pathway, or chemical chain, leading to an autoimmune process (recall HIV) is known to be a trigger for rheumatoid arthritis and possibly other conditions caused by immune system inflammation.

This is, of course, not the only such research to point to nanoparticles as potentially harmful. It could be a significant finding, but that will require confirmation by other labs and eventually studies looking for the effects in people. In this case the specificity of the analysis – a causal route to the development of rheumatoid arthritis – provides a good starting point for studies.