The International Organization for Standardization (ISO) recently published standard ISO/TR 19601:2017, “Nanotechnologies — Aerosol generation for air exposure studies of nano-objects and their aggregates and agglomerates (NOAA).” ISO states that, to evaluate the inhalation toxicity of NOAA, it is important to consider certain parameters that make the toxicity testing relevant to human exposure. Three critical aspects to consider when designing and conducting an inhalation toxicity study are:
- Uniform and reproducible nano-object aerosol generation that is relevant to realistic exposures,
- Thorough characterization of nanomaterials throughout the duration of testing including starting and generated materials; and
- Use of occupational exposure limits and reference concentrations (as derived from existing studies and/or real-time exposure monitoring data) for dosimetry.
Therefore, according to ISO, to conduct in vitro and in vivo NOAA studies, “it is important to choose an appropriate NOAA aerosol generator and use online and off-line techniques for nano-object characterization.” The standard describes methods for producing NOAA aerosols for in vivo and in vitro air exposure studies. The purpose of the standard is to aid in selecting an appropriate aerosol generator to fulfill a proposed toxicology study design. The standard describes characteristics of aerosol generation methods, including their advantages and limitations. ISO notes that the standard does not provide guidance for aerosolization of specific nano-objects.