Safety Evaluation of Engineered Nanomaterials for Health Risk Assessment: An Experimental Tiered Testing Approach Using Pristine and Functionalized Carbon Nanotubes

Figure 4

Representative H&E-stained lung parenchyma specimens. (a, b) Normal lung architecture in control animals. (c–f) Structural alterations detected in treated rats, i.t. exposed to 1 mg/kg b.w. MW-COOH (c, e) or MW-NH₂ (d, f). Dark, particulate-laden macrophages, evident as a consequence of the carbon nanotubes engulfing, at alveolar (c, d), bronchiolar (e), and stromal (f) levels. (d) Thickened-walled collapsed alveoli accompanied by the presence of widespread microhaemorrhagic foci. Objective magnification: 40x (a–d); 60x (e, f).

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