On request by the Swedish Armed Forces, the Swedish Defence Research Agency has performed a literature study, aimed at concluding the available knowledge regarding tracer grenade m/39, of German origin. That ammunition type was dumped in several lakes during the fifties and sixties. On one occasion, it has been needed to clear a ammunition dumping ground: Ala Lombolo lake in Kiruna municipality. That operation was very costly and the Armed Forces has requested possible ways to decrease the costs for coming clearing operations. Different actors have performed investigations on salvaged grenades during the past decades. In this report the reports are referenced, and comments from FOI on the reports are presented. The conclusions of the investigations differ, why the level of risk has been based on conservative risk assessments. Four possible options for further investigations are discussed and the conclusions from the discussions are: 1. The knowledge available today does not provide facts that can decrease the level of risk. 2. It is not likely that sensitivity testing of grenades, in combination with dissection and analysis on the grenades, will provide reasons for decreasing the risk level. 3. The risk for spontaneous ignition of the propellant is unlikely, but cannot be ignored.