The world of nanoscience is populated by nanoparticles. These are assemblies of atoms between one and one hundred nanometers in size, which can be held together by chemical bonds or weaker forces. Nanoparticles can exist in free form, agglomerated or integrated into a material to confer interesting properties (electrical mechanics, bactericide, etc.).
The manufacture of nanoparticles goes back a long way, with compounds such as nanosilver, carbon black and nano-silica being known for over half a century. They are now produced at a rate of just over ten million tonnes a year, spread over several thousand species. They are increasingly found in a wide range of products from a variety of sectors (sports, home and garden, automotive, etc.), which are regularly inventoried by various organizations (see www.anec.eu and www.beuc.eu).
In the early 2000s, questions were raised about the health effects of such particles. Cases such as the toxicity of asbestos (production of which reached five million tonnes in 1975 before declining, and whose effects on health are well known) and fine particles in the atmosphere, which have a proven effect on health (increased risk of cardiovascular disease), have contributed to this questioning. This raises the question of the risks associated with nanoparticles, whether they escape from a material as a result of wear and tear, or are produced during combustion. As with chemical substances, nanoparticles can enter the body by various routes, including ingestion or inhalation, and affect health.
