[abbasmehdi]

Wow, anything written on the subject?

[lgv]

There's this:

http://www.window.state.tx.us/border/ch09/cobalto.html

[aristus]

Surprisingly it's hard to track down. The Wiki article linked abode has one or two mentions of a "Mexico incident", but that's it. Here are some others:

http://www.nytimes.com/1984/05/01/science/nuclear-spill-at-j...