Why are there concerns about the safety of nanoparticles?
People have known for a long time that there are potential health effects which may arise through exposure to particles, for example pneumoconiosis from exposure to coal dust or mesothelioma and lung cancer from exposure to asbestos. In general, the likelihood of illness developing depends on the toxicity of the particle and the level and duration of exposure. Factors which influence the toxicity of particles include the surface area of a particle, how reactive that surface is and where that particle can travel to in the body. Because of their small size, nanoparticles will have a much higher surface area relative to the same mass of larger particles. They are also being designed to have different and in some cases more reactive surfaces. There small size leads to the possibility that they can also more easily cross cell and other boundaries. All of these three factors have led scientists to conclude that some nanoparticles may be more toxic than larger particles of the same materials.
