The United Nations, European Space Agency (ESA), NASA and other space nations are actively working to try and reduce the amount of space debris, but space experts warn it's only a matter of time before a major impact occurs during a human or robotic mission aboard the International Space Station, or elsewhere in space. "Space is pretty big, but after a while it can get crowded, especially in the region where these things are," according to David Wright [2], co-director of the Ploughshares-funded Union of Concerned Scientists' Global Security Program [3].
Links
[1] https://www.ploughshares.org/file/200
[2] http://ploughshares.org/expert.php?id=143
[3] http://www.ucsusa.org/nuclear_weapons_and_global_security/
[4] http://www.dailytech.com/Space+Nations+Unsure+How+to+Handle+Space+Junk/article14304.htm