There are devices which can detect various radio-isotopes in an unknown
sample.  Unfortunately  they cost around $10,000 - $15,000 each.  I used to
teach people how to use them.  Potassium Iodide is only good for exposure
to radioactive iodine, as it preferentially seeks the thyroid.  It won't
help for anything else.

I won't eat any marine apex predator fish, like tuna, because of
bioamplification of mercury and pesticides.  Radioactive contamination is
just another justification for that stance.

One interesting thing about kelp is that only certain ethic groups have
evolved the enzymes necessary to digest it.

-- 
Keep the books,
Burn the censors
---------------------------
Ignore Faux News