In its Post-Conflict Environment Assessment on Lebanon the United Nation's Environmental Program (UNEP) published the results of their findings on the supposed use of (depleted, natural or enriched) uranium weaponry by the Israeli Defense Forces in Lebanon. The investigation has not found any evidence that such weapons have been used. The attention was especially focussed on soil samples from a crater in the neighborhood of Khiam in southeast Lebanon. Reports and rumours went the rounds in the international media during and after the 2006 war regarding the use of depleted uranium and/or uranium weapons at this specific site at Khiam.
The laboratory analysis of one of the soil samples confirmed the higher natural uranium levels present at the site. The analysis showed 26.2 mg uranium per kg, which is higher than the average by a factor of about 10. Such a higher value is not extraordinary. For example the baseline levels of natural uranium in Europe vary between 0.21 to 53 mg/kg in topsoils and 0.19 to 30 mg/kg in subsoils*. Therefore UNEP's conclusion that the found value could not a priori be linked to a missile/bomb is justified.
Besides the explanation of natural variation there are also other possible explanations of the higher concentration of natural uranium in the crater at Khiam. UNEP found that the crater had been the result of an air-to-ground attack on two buildings in the Khiam residential area. The higher natural uranium concentration could be the result of destroyed ceramic stones used in houses or could be from the use of artificial fertilizer. Products from which it is well-known that they often contain higher concentrations of natural uranium.
UNEP: Lebanon Post-Conflict Environmental Assessment
* Plant, J.A. et al.; The distribution of uranium over Europe: geological and environmental significance. Applied Earth Science : IMM Transactions section B, Volume 112, Number 3, December 2003, pp. 221-238(18). Maney Publishing