ELI5 Asbestos - how does it cause cancer?

Why is a town in Canada called Asbestos? If cancer is a bad mutation of a cell, how does a fiber like asbestos cause it? What made asbestos so popular in the first place? If asbestos causes cancer, why isn't fiberglass as deadly?   ... We explain like i'm five!   Thank you to the r/explainlikeimfive community as always and in particular the following users whose questions and comments formed the basis of this discussion: toproy, raygun_gaming, phage0070, prodigalhacker, siciliandeathmatch, idontremembernames, jorand, kaiverus, tungsten_wookie & demanbmore. To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Send us an e-mail: [email protected]