What?

Abandoned is a mod that adds old and dangerous things that were largely used before discovering that they were in fact toxic / not safe to work with. An example of this is Asbestos, which was used in buildings to reinforce them. This substance was fibrous and its fibers were very small, so small that when inhaled they could cause asbestosis and other complications. When they discovered this it was already too late and many buildings were abandoned for that reason.