I think the dangers of plutonium dust are grossly over rated (we we're all being dusted by plutonium when they were doing atmospheric tests back in the 1960s). Plutonium is far more dangerous inside a nuclear explosive than as a poison.

Concerning the Golden Gate Bridge: That's the most obvious potential terrorist target in Northern California. I've been trying to figure out how a terrorist might attack the bridge but can't come up with a plausible scenario. For example they could crash a plane into the bridge. That would damage the road and/or the box supporting the road but I doubt a plane could seriously damage the cable or towers. The city of San Francisco could probably fix the road in a couple of weeks. The bad guys could place an explosive device on the cable. However that cable is several feet thick and essentially a bundle of piano wire. I think even plastic explosive (C-4/Semtex) would do little more than blacken the paint unless it was backed up with a heavy tamp. I can't image the bridge authorities allowing a bunch of terrorists to assemble a heavy explosive device around one of the cables. I think the bridge is just too hard a target for the bad guys to hit (I hope this isn't famous last words).

Gary