Characterization of aerosols generated from nine nanomaterial powders: reliability with regard to in vivo inhalation toxicology studies

In experimental toxicology, when simulating human exposure to aerosols in the working environment, inhalation is the route of administration of choice for evaluating the toxicity of a given material (in aerosol form) in animals. In this context, this work aimed to contribute to the establishment of recommendations concerning the characterization of aerosol tests in inhalation toxicology studies. In particular, the work consisted of experimentally characterizing test aerosols using a given generation method to be used for inhalation toxicology studies. Nine nanomaterial powders have been investigated (four types of TiO2, two types of SiO2, ZnO, CeO, and BaSO4). The aerosols produced cover the particle size range from a few tens of nanometers up to several micrometers and are mainly composed of aggregates and/or agglomerates. The work carried out shows that generation and characterization of test aerosols for inhalation toxicology studies is a complex but essential element of inhalation studies, for which the conditions required (stability, repeatability, level of concentration) are sometimes difficult to obtain. Moreover, this study highlights the necessity to carry out preliminary tests to ascertain the performances of the chosen devices and their suitability for inhalation toxicology.