Abstract
The green chemistry and the health implications of nanoparticles are analyzed. Difficulties abound in devising such regulations, beyond self-imposed regulations by responsible companies, because of the likelihood of different properties exhibited by one type of nanoparticle, which are tuneable by changing their size, shape and surface characteristics. Green chemistry metrics need to be incorporated into nanotechnologies at the source. Nanoparticles can enter the human body through the lungs, the intestinal tract and to a lesser extent the skin, and are likely to be a health issue, although the extent of the effects on health are inconclusive. Nanoparticles can be modified to cross the brain blood barrier for medical application, but this suggests that other synthetic nanoparticles may unintentionally cross the barrier.