Simply put....there comes to a point where there is always a threashold when there is too much of a good thing. Anything can become toxic in too large of a dose. And as you decend the partial pressure of oxygen increases and if that parial pressure of oxygen exceeds what the body is used to or can handle...then bad things happen. It is just the same as with individuals and alcohol or nitrogen for that matter. There might be some people that can handle a higher PO2 just like there are people can handle more alcohol or dive deeper without experiencing the same narc effects....
or something like that...
or something like that...
