“Why are shellfish so dangerous? Because they are many times more polluted than the filthy waters they inhabit.
Unfortunately they choose to live and love and multiply in estuaries along coastal regions. These estuaries are particularly subject to discharge of sewage, sewage effluent, and other water-borne pollution from municipal discharges, from suburban home drainage and agricultural runoff.
The polluted aspect of their habitat is one danger. The fact that they are filter feeders compounds the danger.
Oysters, for instance, because of their way of obtaining and absorbing food, have been found to concentrate polio virus up to 20 to 60 times the level of the surrounding seawater.
No other animal food offered on the menu of your favorite eating place would be served to you along with its feces. Yet this is the case with seafood. It is served whole; complete with its intestinal tract.”