So the only logical conclusion is that Israel poisoned his toothbrush with polonium!
I admit, I first saw this patently ridiculous theory in Al Quds, and thought it was just another Arab conspiracy flight of fancy. Now I see it was originally published in The Daily Mail - in an article so dumb that it pretends that the Lancet piece reveals new information. (Of course, Arab media is enthusiastically republishing it.)
The Swiss scientists tested for polonium levels in a lot of objects, some that belonged to Arafat and some control items that didn't. Arafat's toothbrush had slightly higher concentrations of polonium than the urine stain in his underwear. But the sample that had the third highest concentrations of polonium did not come from Arafat.
It came from a toothbrush of control subject.
As the scientists wrote then:
Bristles from toothbrush present another problem. They appeared clearly contaminated when sampled from Mr Louvet [Arafat] belongings (54 mBq/g). Nevertheless a control measurement carried out on a toothbrush from IRA collaborator 1 also shows a significant activity (21 mBq/g) while a second control measurement on a toothbrush from IRA collaborator 3 presents only a background value (1.0 mBq/g). Thus the measurement of Mr Louvet [Arafat] toothbrush is not conclusive and only the further determination of supported 210Po will give an answer concerning a possible contamination of the toothbrush by unsupported 210Po.Even without this, the theory is beyond dumb. Wouldn't one expect significantly higher concentrations remaining on the item that was used for poisoning, versus the very much watered down bodily fluids? It is as if the "reporter" cannot see beyond a Hollywood version of events - "ooh, the camera focused on the toothbrush in an early scene, and I'm smart enough to have noticed it!"
No theory is too stupid as long as Israel can be blamed.
(Interestingly, the Lancet article appendix shows completely different concentrations of numbers than the original report, and the IRA toothbrush suddenly had almost no polonium. Not sure why. Were their methods flawed during the original Al Jazeera media blitz? Perhaps the science of detecting and measuring trace amounts of plutonium after 20 half-lives is not as advanced as they pretend?)
(corrected IRA ref, h/t Ian)