> I hope I've not said anything misleading or trod on anyone's toes. I am not > a specialist in radiation science. Chris Perhaps we should get Homer Simpson to comment: he's not a real radiation safety expert but he play's one on TV ;o) Terrorists do not need significant amounts of radioactive material to cause terror. PLUTONIUM HITS LONDON If in London someone exploded a firecracker surrounded by 37,000 Bq of pure Plutonium-239 and the press reported it it would frighten thousands. Plutonium is after all the most dangerous element known to man (sic). the point is that the terror value of the word "plutonium" persists whether or not the health risk is significant. I expect actually that the Government would prefer to report "only 0.00,001 Curies". OK, an exteme example. But even such a low amount would scare the public - and be safer for the terrorist to habndle. Oh, photographically, cadmium and lead filters ...