Where can I recycle spark plugs?

As a materials engineer I know how toxic Yttrium and Platinum can be if disposed of improperly. I just wanted to know if there is somewhere I can safely recycle my old spark plugs. If it helps, I live in Pittsburgh, PA.Where can I recycle spark plugs?You might want to check the EPA website for drop-off locations. Most communities have a annualy hazardous waste drop-off day where people can bring old paint, oil, etc. for recycling or proper disposal.