Radioactive isotopes are one source of radiation, insolation and cosmic background radiation are others. In this case the OP was referring specifically to maximum radiation exposure levels as defined by some big-"I" international organization.
No. It is not. There is alpha, gamma, beta+ and beta-. And there is a huge difference. And how healthy it is strongly depends on the area of you body that is exposed. If Your skin is exposed to alpha radiation it can be as harmless as a sunburn (it's a matter of the dosis). If you get alpha radiator into your bloodstream that's a whole different story at the same dosis.
That still confuses radiation with radio-isotopes which are sources of radiation. If you consumed a highly radioactive isotope you would likely get more radiation not different radiation.
If a single bioloogically consumed radio-isotope molecule put out the same amount of radiation as the annular insolation in Denver, then you would likely get more localized damage from the ionizing radiation at its point of binding. If it were multiple molecules (measured in parts per billion) and they in aggregate summed to the annual insolation in Denver, then its no more dangerous than the annual insolation in Denver.
Alpha particles and energetically ejected electrons and positrons are ionizing radiation just like gamma rays, and its the amount and concentration, not the source, that matters.
Radioactive isotopes are one source of radiation, insolation and cosmic background radiation are others. In this case the OP was referring specifically to maximum radiation exposure levels as defined by some big-"I" international organization.