Toxic Antiquities: Lessons from the Louvre

The announcement today that the Louvre would be returning tomb fragments to Egypt raises more disturbing questions. It is being reported that one of the pieces first surfaced at a London auction in the early 1980s. Are museums taking the 1970 benchmark seriously? Does the due diligence process demonstrate a recorded collecting history that can be traced back prior to 1970? Are museums too eager to acquire?

How many other toxic antiquities are still in museum collections?