I love the idea of warning of an “unquantifiable” hazard. Of course, many many hazards are unquantifiable, or at least unquantified — after all what’s the probability, precisely, associated with drinking irrigation water or allowing children to pump gas?
It’s also worth noting that most people — or is that just most people here in North America — would have very little idea what the word “unquantifiable” means. It seems rather a subtle point to put on a sign, really.
Thanks to Ursula Wills-Jones for the picture.