The reported foiling of a 鈥渄irty bomb鈥� plot by UK intelligence agencies has left experts divided over the likelihood that the chemical cited, osmium tetroxide, would be a weapon of choice for terrorists.
The alleged plot to attack the UK, revealed by unnamed sources, is said to have been discovered after the interception of emails and phone calls referring to osmium tetroxide by UK agencies working with the US National Security Agency.
While the content of those communications has not been made public, the suggestion is that adding the toxic chemical to a conventional explosive device would increase the harm it caused on detonation by poisoning people in the vicinity.
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鈥淏ut the question really is 鈥榳hat happens if it is used in a bomb?鈥�,鈥� says Alastair Hay, an environmental toxicologist and a chemical weapons expert at Leeds University, UK.
Blast ventilation
Hay told 快猫短视频 that osmium tetroxide is poisonous enough to kill in high doses, but suggests that much of the highly reactive compound might be destroyed in any blast. Furthermore, the force of a blast might ventilate a target area like a shopping centre, so the toxic fumes would disperse.
鈥淭here is no doubt that it is toxic,鈥� agrees Andrea Sella, an inorganic chemist at University College London. 鈥淏ut I think that going for fertiliser and nails seems more straightforward and is less likely not to work out,鈥� he told The Guardian newspaper.
Hay and Sella also believe osmium tetroxide is too costly to be an obvious choice for terrorists. 鈥淏ecause of its expense I鈥檝e wondered why someone would chose something like this for a bomb. Osmium is in the same sort of category as platinum, it is a rare metal,鈥� says Hay. Websites quote prices between $40 and $180 per gram.
Another factor arguing against the likelihood of osmium tetroxide being used is that it has an acrid odour, which would alert victims to its presence. However, it can only be detected by smell at concentrations above 2 parts per million, while the safety limit for laboratory use is just 0.002 ppm.
Choking and burning
Osmium tetroxide (OsO4) is toxic to people because it reacts with tissue, explains John Henry, a poisons and toxicity expert at Imperial College, University of London.
鈥淭herefore it will produce coughing, choking, dizziness and tightness in the chest,鈥� he told 快猫短视频. 鈥淚t will stain and burn the skin and also stain and burn the [eyes] 鈥� it can destroy the cornea.鈥�
Although it is a solid at room temperature, it can easily sublime into a toxic vapour and is only handled by laboratory researchers in fume cupboards. They use it as a powerful oxidising agent and to stain samples in some types of microscopy.
Henry thinks the reported interest of terrorist suspects in the compound is a serious concern. 鈥淚 think it鈥檚 a more toxic substance than sarin,鈥� he says. Sarin gas attack was used by a Japanese doomsday cult to kill 12 people and hospitalise 5000 others on the Tokyo subway in 1995.
鈥淚f you can find a means of dispersing osmium tetroxide, it could really do a lot of damage,鈥� he warns.
The UK鈥檚 Government Communications Headquarters (GCHQ), which supplies signals intelligence to other departments, declined to comment.