Smoke detector radiological sources, teflon pans, noble gases and refridgerants, cadmium paints and pigments, dioxins, kepone, BPA, hydrazine, sulfur mustards, medication, depleted uranium. The list goes on.
It seems unclear to me whether their deal with restaurants is limited to collecting shells from restaurants or includes distributing oysters to restaurants as well. Hopefully it's only the former. One hopes the oysters being served are not local.
They collect the shells of edible oysters grown in less polluted areas. These are cleaned and used to jumpstart the NYC oyster colony, which are not yet edible.
Whether you're consuming the local waste or waste from somewhere else doesn't make much of a difference.