Nanotechnology refers to the manipulation of matter on the scale of the nanometer (one billionth of a meter). Nanoscale science operates in the realm of single atoms and molecules. At present, commercial nanotechnology involves materials science (i.e. researchers have been able to make materials that are stronger and more durable by taking advantage of property changes that occur when substances are reduced to nanoscale dimensions). As nanoscale molecular self-assembly becomes a commercial reality, nanotech will move into conventional manufacturing and it is already changing healthcare, food and drug production. Nanotechnology involves profound social , military and environmental risks, with new nanomaterials potentially threatening raw material economies of the south and posing new health risks to workers and the public at large.