English: Nanotechnology is a system of innovative methods for controlling and manipulating matter at the near-atomic scale to produce engineered materials, structures, and devices. Engineered nanoparticles are generally considered to include a class or subset of these manufactured materials with at least one dimension of approximately 1 to 100 nanometers (www.nano.gov/html/facts/whatIsNano.html). At these scales, materials often exhibit unique properties beyond those expected at the chemical or bulk level that affect their physical, chemical, and biological behavior. The term "ultrafine" is also frequently used in the literature to describe articles with dimensions less than 100 nanometers that have not been intentionally produced (e.g., manufactured) but are the incidental products of processes involving combustion, welding, or diesel engines. It is currently unclear whether a distinction in particle terminology is justified from a safety and health perspective if the particles have the same physicochemical characteristics.

The potential occupational health risks associated with the manufacture and use of nanomaterials are not yet clearly understood. Many engineered nanomaterials and devices are formed from nanometer-scale particles (i.e., nanoparticles) that are initially produced as aerosols or colloidal suspensions. Exposure to these materials during manufacturing and use may occur through inhalation, dermal contact, or ingestion; however, inhalation exposure is the main route of concern [ASCC 2006]. There is very limited information available about dominant exposure routes, the potential for exposure, and material toxicity.

DHHS (NIOSH) Publication Number 2009-116