Four studies in the second half of 2012—one of which described the people of Fallujah as having "the highest rate of genetic damage in any population ever studied"—renewed calls for the US and UK to investigate the possible links between their military assault on the city in 2004 and the explosion in deformities, cancers, and other serious health problems. Despite the known use of depleted uranium by allied forces, no depleted uranium has been found in soil samples taken from Fallujah.