Why does extrapolation among human populations pose problems?
As discussed earlier, extrapolating results from one species to another is problematic due to differences in how species respond to radiation. Even though humans are all members of the same species, there are similar problems when extrapolating results from one group of humans to another group. Within the human species, different groups can have different rates of disease. For example, stomach cancer is much more common and breast cancer much rarer among Japanese than among U.S. residents. How then should estimates of the radiation-induced excess of cancer among the atomic bomb survivors be applied to the U.S. population? Assumptions are needed to “transport” risk estimates from one human population to another human population that may have very different “normal” risks.
