i’ll be blunt - for someone that isn’t used to read scientific studies in the domain you cited - it’s darn near impossible to get a clear picture of what is at stake here.
in laymens terms i think what this “absorbtion” word means in this case could be better understood by simply imagining the following scenario.
one man lays on the ground different stone slabs by varrying densities and sets up above each stone a mechanism that drips water dropplets at same time intervals with the same volume per drop of water then over time he measures how each stone slab is influenced by the falling drops. this is done over the course of a few thousan years in order to have a clear indication or can be accelearated through concentrated water jets that are closely monitored in the same equal manner as with the droplets.
this example is far feched as it is about something else entirely but maybe it can spur some ideas in readers about the complex issues involved here.
my point is that like the stone material each human body is slightly different overal regarding exposure tolerances but each body will get affected for SURE more or less depending on the individual conditions. better safe than sorry !