Some of the next big nasty lawsuits are going to come from Fiber Reinforced Concrete. They use it a lot in precast especially architectural precast panelsand in bridge beams. When you are around that stuff when it is being crushed or when a building is imploded the dust is really nasty. The original fibers were asbestos and as the technology progressed they replaced it with fiberglass and in some cases metal.

You get a big cloud of that mixed with respirable silica and watch out.