Essentially the only personal items that had huge amounts of polonium were Arafat's underwear and toothbrush, with a bloodstain on his hospital cap having a significant amount as well. But the report found that the toothbrush bristles had similar levels of polonium as that of a control toothbrush (from an IRA collaborator). So most of the "smoking gun" comes from the urine sample in the underwear.
Here is what the report says:
The cumulative urinary excretion and the daily urinary excretion after acute intake by ingestion of 210- Po are shown in Figure 7 and 8. A good agreement was found between the values of cumulative urinary excretion reported by Harrison et al. and those calculated in our study (see Figure 6).The authors note that 1 GBq will kill a man in a month. They then note that this amount would yield about 1.4 mBq in the urine after some 20 half-lives of decay, in February 2012.
Regarding the poisoning of Mr. Litvinenko by 210-Po in November 2006 in London, Harrison et al.  concluded that 0.1–0.3 GBq or more absorbed to blood of an adult male is likely to be fatal within 1 month. This range would correspond to an intake of 1–3 GBq or more, assuming f1=01. Based on their study, Li et al.  found that the estimated amount of 210-Po ranged from 27 MBq assuming f1=0.5 to 1.4 GBq assuming f1=0.1.
Considering a poisoning by ingestion of 1 GBq of 210-Po (f1=0.1), it is expected to find about 500 kBq/day in urinary excretion the first 10 days after intake, about 250 kBq/day between 10 and 20 days and about 150 kBq/day between 20 and 30 days, according to Figure 8. Note that for a daily urinary excretion of about 1000 ml/day, such a concentration of 210-Po might have been observed in the gamma spectrometry analysis of 2004 (we estimated the detection limit at 25 kBq/l). Then, assuming that about 2 ml of urine might be found in the underwear with urine stains, we expect that 1 kBq can be found in the underwear if it is worn during the first 10 days after intake. This activity of 1 kBq in October 2004 corrected for radioactive decay of 10 Po (T1/2 = 138.4 d) gives about 1.4 mBq in February 2012. For comparison, an activity of 180 mBq was found for the urine stain of underwear (A) (see Table 2).
And then they say that they measured 180 mBq in February, over a hundred times more!
But doesn't that mean that Arafat ("Mr. Louvet" in the report) would have ingested over 100 Gbq of polonium in 2004 - 100 times the dosage that kills within a month? If so, how did he survive as long as he did after he took ill?
Moreover, if he would have taken a lethal amount, they note that the French doctors would have observed that in their gamma spectography analysis in 2004. Yet they didn't.
Finally, and in addition to our alpha-spectrometric analysis, we re-analyzed the raw data of theCould it be that the samples were contaminated with trace amounts of polonium in the intervening years?
gamma spectrometry performed on urine samples by the French government before Mr Louvet's death. We did not detect any abnormal gamma activities. In particular, we checked the area around the energy 803 keV that is (weakly) emitted by 210-Po. We did not find any evidence of this nuclide in the spectra.
This gets into the realm of conspiracy theories, which I am no fan of, but one other fact needs to be mentioned: You can buy tiny, but safe, amounts of polonium over the Internet.
UPDATE: My theory isn't so far-fetched . An expert in Israel talked to the Jerusalem Post and came up with the same conclusion:
The high levels of the radioactive poison polonium reportedly found on the belongings of the late Palestinian leader Yasser Arafat indicate that the toxin was planted on them long after Arafat's death, a senior counter-terrorism analyst told The Jerusalem Post Thursday.
Dr. Ely Karmon, of the Herzliya Interdisciplinary Center's Institute for Counter-Terrorism, is a specialist in chemical, biological, radiological and nuclear terrorism.
Responding to an Al Jazeera report published Wednesday, which said that specialists at the Institut de Radiophysique in Lausanne, Switzerland, discovered abnormally high levels of polonium on Arafat's belongings, Karmon said that the half life of the substance would make it impossible for polonium to have been discovered at such high levels if it had been used to kill Arafat eight years ago.
According to the Al-Jazeera report, polonium has a half-life of 138 days, "meaning that half of the substance decays roughly every four-and-a-half months."
And yet, eight years after Arafat's death, the Swiss scientists reported finding polonium levels of 54mBq and 180mBq on his belonging, considered to be high levels.
"If it had been used to for poisoning, minimal levels should be seen now. Yet much higher levels were found. Someone planted the polonium much later," Karmon said.
"Because of the half life of the substance, the conclusion is that the polonium is much more fresh," he added.
....After Arafat's death, "why did neither Suha nor the PA agree to release the French hospital's medical file?" he added.
(h/t CHA and Sasha)