What I mean is that we can't just take the most radioactive beaches in the world and assume that this is the normal level in beaches so "is not so bad". In the real life, beaches aren't made (only) of granite dust. Most material is silicon, carbon and calcium.

And we should remember that unless x-chest rays, thousands of people lay practically naked in the same beach and favourite spots for entire weeks, ten hours a day. Being exposed to the UV rays of the sun also, that is another important source of cancer. In this cases, even relatively low dosis could be of concern.

People at the beach eats a lot of local sea foods also.