Nanomaterials: How Big a Concern?

Nanoparticles are ubiquitous and can be either naturally occurring or manufactured, but researchers are just starting to study them closely, and safety questions remain unanswered. Properties vary greatly from material to material and even within the same element: some carbon nanotubes do not affect human health, for example, while others, like those found in diesel exhaust, may act like asbestos fibers in the lungs.

Nanotechnology deals with materials at the level of 1 to 100 nanometers, with a nanometer (nm) being a billionth of a meter; the ratio of a meter to a nanometer is the same as that of the Earth to a marble. The smallest things visible to the naked human eye are 10,000 nanometers.