Figure 4.

Animal inhalation experiment to predict the effects of human-relevant exposure. (A) The aggregates and/or agglomerates will sediment quickly in ambient air and will be filtered out effectively by the human upper respiratory tract. Humans can be easily exposed to well-dispersed nanomaterials (NMs) in the environment. In fact, human exposure to well-dispersed NMs can result in alveolar lesions. (B) Therefore, suspension of the NMs in biological fluid with aggregates and/or agglomerates does not show the full extent of the effects of NMs on experimental animals. (C) On the other hand, in practical inhalation studies on experimental animals, even though the air in the animal chamber is rigorously agitated to ensure homogeneity of the aerosols, NMs with aggregates and/or agglomerates can enter the respiratory tract of the animal, which makes nanotoxicity evaluation difficult. (D) To address this problem, we developed aerosolized, well-dispersed NMs without aggregates, and/or agglomerates.