this is from the recent report as far as injury inflicted by drones: " if a DJI Phantom 3 drone were to fall on your head, you’d have a 0.03 percent chance or less of sustaining a head injury. In comparison, if a block of steel or wood with the same weight were to come down on your noggin, you’d have a 99 percent risk of injury."
" earlier measurement standards grossly overstate the risks of injury from a drone"


http://www.digitaltrends.com/cool-tech/dji-faa-report-drone-safety/#ixzz4fgzR8GvL