The list, "Radsafe" is an open international e-mail list devoted to the topic of radiation protection (health physics).
Most of the time their discussions are pretty boring, but sometimes you get a keeper or find a hilarious enviro-wacko disruptor sending a message. In this case, they discussed whether or not the missing materials were dangerous, and pretty much concluded they they were, but only to those prone to radiophobia hysteria (kinda like me, sometimes).
For more info see http://www.vanderbilt.edu/radsafe/. These scientists are operating in an academic bubble, not fully realizing their highly technical (and political) advice on radiation & its materials are open to Osama bin Laden if he wanted to look.