like a lot of bad things (like lead) it takes a certain threshold in the body before things really start happening. But oh when they do it's super bad. And bad news it can take a really long time for asbestos to get you even it you have had enough of it in your system to cause problems.Remember asbestos brake pads? How many of us changed them back in those days? Blew out the dust with compressed air? How much did we breath in on the road with cars all around us hitting the brakes? It's a miracle we're alive.