Nano-objects are any materials that have at least one dimension (length, width, height and/or diameter) between 1 to 100 nanometers (nm). Nanoparticles refers to material in which at least two dimensions measure between 1-100 nm. Nanoparticles may be dry particles, suspended in a gas (as a nanoaerosol), suspended in a liquid (as a nanocolloid or nanohydrosol) or embedded in a matrix (as a nanocomposite).

Nanoparticle toxicity depends on the physical and chemical characteristics of the specific nanoparticle, including size, shape, surface charge, stability and chemical composition of the core and shell. There are many unknowns regarding the health risks posed by working with nanoparticles. Factors that influence health risks following exposure include:

• Magnitude and duration of the exposure
• Persistence of the material in the body
• Inherent toxicity of the material
• Susceptibility/health status of the person

Review EH&S’s Guidance For Nanoparticles for additional information.