Functional and toxicological effects of model UFP in a human airway mucosa model – Particle agglomeration may cause atypical concentration-dependencies

Introduction Carbon black (CB) is used as an easily accessible proxy for ultrafine particles (UFP) from diesel combustion, an important contributor to air pollution. CB are well-defined particles<100 nm in size (nanoparticles (NP)) and consist almost exclusively of carbon. Damage can be caused either by mechanical disturbance or chemically through molecules attached on the CB surface. Therefore, not only particle size, but also its capacity to bind molecules determine the toxicity of UFP and NP. Studies in mice show inconclusive data on CB toxicity, whereas cell lines intended to mimic bronchi, lung, and immune cells often report cyto- and genotoxic effects of CB after 2-24h.