Nanotechnologies make use of very small objects or artifacts. Nanomaterials are an increasingly important product of nanotechnologies. They contain nanoparticles, smaller than 100 nanometers in at least one dimension. Nanomaterials are coming into use in healthcare, electronics, cosmetics and other areas. Their physical and chemical properties often they differ from those of bulk materials, so they call for specialized risk assessment. This needs to cover health risks to workers and consumers, and potential risks to the environment.