Additional tests, conducted over a three-month period from March until June, concluded that most of that polonium found in samples of body fluids — sweat and urine — on Arafat’s clothes, was “unsupported,” meaning that it did not come from natural sources.

Al-Jazeera says there is little scientific consensus on the symptoms of polonium poisoning, mostly because it is so rare.

Litvinenko suffered severe diarrhea, weight loss and vomiting, as did Arafat, in the days and weeks before he fell ill.