Open mussels are ok so long as they close when you rap the shell with a knife. The important thing is they are alive when you cook them, any that are already dead will fuck you up.
MN - mussels are tested by the fisheries research centre, they test for specific toxic (to humans) algae that the mussels might have eaten
MN - mussels are tested by the fisheries research centre, they test for specific toxic (to humans) algae that the mussels might have eaten