What about 'War of the Worlds' syndrome? Perhaps you're concerned about liability for frightening the easily-persuaded populace with your fiction. It's highly unlikely you'll run into problems. (The situation might be different if you were claiming something as true when it was not.) Anyway, as history proved in the case of Orson Welles' "War of the Worlds," few people took any action based on the so-called deception. Much of the "panic" was drummed up by newspapers, fearful of radio's encroachment on their turf.
Making Fictional Use of Government Agencies
Dear Rich: Is there any problem with using the name of a state government/public entity, like say the Maryland Dept of Natural Resources and making up something for them to say? I am interested in a potential work of fiction where I pretend they would announce something, for example, Maryland Dept of Natural Resources has declared the state's air as unbreathable and recommends all citizens purchase a gas mask. Is there a problem if the work of fiction contains actual facts too and then this example statement above could be construed as true by some, then people get upset or concerned and feel they should take action to protect their health? There should be no problem using real government agencies in fictional thrillers. It's all permitted under the free speech banner (and if it weren't so, Tom Clancy would be out of work).