ABSTRACT
The Organization for Economic Cooperation and Development and the International Organization of Standardization have been actively involved in this field in order to provide international guidelines that would facilitate the work of scientists and regulators in nanomaterial risk assessment. While intratracheal instillation and short term inhalation studies could be used for hazard assessment and toxicity ranking, sub-chronic, and chronic inhalation assays have been of great value for risk assessment and threshold limit value (TLV) determination. To date there is no regulatory occupational exposure limit (OEL) specifically calculated for nanomaterials. Inhalation studies in rodents are of great value for assessing hazards and risks associated with the exposure to nanostructured aerosols. However, in order to generate exploitable data for legislators and regulators it is important to perform a thorough characterization of the aerosol and whenever possible to make sure it is representative of an occupational or environmental exposure in terms of aerosol size distribution but also concentration.
