Role and impact of nitrogen on global healthhttp://moduleblog.nus.edu.sg/blogs/lsm4261/archive/2008/04/08/role-and-impact-of-nitrogen-on-global-health.aspxWhere did it all come from? Vaclav Smil. Millennium Essay: Detonator of the population explosion. Nature, 400: 415 (29 July 1999). Link downloads a pdf . An excellent review about impact: "Global Nitrogen: Cycling out of Control." By Scott Fields. EnvironenCommunityServer 2.1 SP2 (Build: 61129.2)