Easier said than done
Proving something safe is really impossible. With new instruments we can detect minute quantities of dangerous chemicals--but at these level the risk is for all practical purposes 0.
Then we have the issue of defining "safe". If this chemical effects 1% of the populations is it safe? What if it effects 0.1%? 0.001%? How far do you go?
Swimming pools kill thousands of Americans every year -- mostly children--shall we ban them?
I could go on and on, but I think you get my point.
BTW had the World Trade Center been insulated with Asbestos it would have stood for 3 to 4 more hours before collapsing, allowing time to evacuate everyone below the impact point.
