Nanoparticles are particles which have at least one dimension below 100 nm. A nanometer is a billionth of a meter.

Nanoparticles are categorized depending on the origin. Natural nanoparticles are those that are produced from nature, for example volcanic ash and ocean spray. Anthropogenic nanoparticles are produced by man and can either be incidental, for example emissions from diesel engines, or engineered nanoparticles that have been deliberately manufactured.

Due to their small size, nanoparticles have different physical and chemical properties than their larger counterparts. The field of nanotechnology seeks to take advantage of these special characteristics by engineering nanoparticles with specific functions.

Engineered nanoparticles are widely used for bio-medical applications, particularly for therapeutic and diagnostic use, for example drug delivery, early cancer detection and treatment, bio-imaging, sensing and gene therapy. Environmental uses of engineered particles covers the area of water remediation, pollution control, and harnessing clean energy. In the electrical world they can be applied and used as chips due to their high electrical and optical properties, for example in computers, antennas of televisions and other electrical signals in televisions, radios and phones. They have been developed to reinforce materials by making them more flexible, durable and resistant to destruction. They are used in making stainless fabrics, long lasting tennis balls, shoes, glasses, rubber and better car tyres.

Currently, the field of nanotoxicology aims to determine the toxicity of nanoparticles. Nanoparticles have unique properties that make them useful for new applications as compared to their larger “bulk” counterparts; however these same unique properties can also potentially cause toxic effects that are not seen with bulk materials.

The NIOH with the support of local and international collaborators has undertaken a Sponsorship Program for the Testing of Manufactured Nanomaterials. The program was initiated to determine a standard for risk assessment of gold nanoparticles at acute, subchronic and chronic exposures in in vitro and in vivo studies as specified by the Organization for Economic Cooperation and Development (OECD).