A comparative transmission electron microscopy study of titanium dioxide and carbon black nanoparticles uptake in human lung epithelial and fibroblast cell lines

► MNP accumulation study in bronchial cells and pulmonary fibroblasts using TEM. ► MNPs are widely and rapidly internalised by both cell types. ► MNPs accumulate chiefly as aggregates in cytosolic vesicles. ► Carbon black and titanium dioxide MNPs have similar accumulation patterns. ► Intracellular MNP accumulation is dissociated from cytotoxicity.