http://www.llnl.gov/csts/publications/sutcliffe/

Here's a teaser...

"Following the seizure of 10 ounces of plutonium at the Munich airport in August 1994, some press accounts stated that terrorists could kill "hundreds of thousands of people" by introducing plutonium into a municipal water supply. In response to such incorrect and misleading statements, we describe the acute and long-term health effects that can arise from ingesting or inhaling various amounts of plutonium. "

Summary:

1)Pu is pretty dangerous stuff if you put it in a bag and inhale it.

2)No one's stupid enough to do #1.

3)Cigarettes are about 150 times more lethal than
inhaling .001 mg of Pu.

4)It really isn't that toxic either, compared to other things. Who is going to EAT half a gram of plutonium anyway?