Concentrations are higher in hot tubs, yes. Additionally, the hot water causes your skin to absorb even more of the chemicals (even if the chemical concentration had been the same), so while I believe the exposure to the hot tub is safe, I'm iffy on the chemicals.
For us: A nice soak on special occasion? Sure. A regular dip in a hot tub? No.
Also, a lot of hot tubs run bromine instead of chlorine. Chlorine is bad for you, but bromine? Oh man.....it's really nasty.