I'd say it depends on where you live and how many drunken parties occurred on the beach?
When I live on the coast, I wouldn't even eat anything that had been in that water. If you want huge quantities of red algae, then that sand would be perfect. If you live on a pristine, seldom used shoreline with no random debris and crap... then it should be OK... as Lupin said, rinse well. I'd even consider heating it to kill off algae, microscopic critters, and bacteria.