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It's actually very, very difficult to prosecute because they can always claim it's just a different interpretation of the same data, or certain details weren't known at the time, or the means of measuring have changed, or whatever. All of those are legitimate issues that have come up time and again, so it wouldn't be hard to use them as an excuse for your asbestos-is-a-safe-food-additive paper. Look at Robert Kehoe, the man who's most famous for telling us that tetraethyl lead was safe, he got his start at Kettering Labs "proving" that the known carcinogen naphthylamine was actually perfectly safe for use in paints, and went on from there. It took decades of fighting by some US cancer foundation whose name escapes me at the moment to get this overturned. So if it's that hard to overturn bought research "proving" that a carcinogen that produces cancer in nine out of ten employees exposed to it is safe, imagine how hard it'd be to overturn something far more vague.