Development and validation of an inhalation system suitable for rodent exposure to carbon nanotubes

Due to their physical and chemical properties, carbon nanotubes (CNTs) are among the most promising nanomaterials in terms of industrial use. In order to assess their toxicological properties, inhalation experiments performed on laboratory rodents remain the most suitable and reliable approach.
In this framework, INRS has designed an experimental facility which meets the highest requirements for animal testing in terms of protection of operators against risks associated with nanoparticles and biohazard. Named NanoTIREx for Nanomaterial Toxicology Inhalation system for Rodent Exposure, this system has been designed according to OECD guidelines for the testing of chemicals and is mainly composed of an aerosol generation system and inhalation towers for nose-only exposure.
CNTs aerosols were produced by an acoustic generator. The integrated control of the exposure conditions (flow rates, temperature, RH, relative pressure, etc.) was managed and recorded using a dedicated software.
Aerosol monitoring and in-depth characterization were performed directly on the inhalation towers and ensured by real-time devices (condensation particle counter, optical particle sizer, scanning mobility particle sizer, aerodynamic particle sizer and electrical low pressure impactor) and samples taken for off-line analyses (gravimetric analysis, mass size distribution from cascade impactor, TEM observations).
Sub-acute inhalation experiments (2×3 hours/day, 5 days/week for 4 weeks) have been performed in female Sprague Dawley rats with two CNTs: the “long and thick” NM401 and the “short and thin” NM403. Two levels of mass concentration were tested for both CNTs: 0.5 and 1.5 mg.m-3.
This work was supported by the European Commission through the 7th Framework Project (NanoReg project, Grant agreement n° 310584).