Contamination and the Cold War legacy thumb|U.S. and USSR/Russian nuclear weapons stockpiles, 1945–2005|alt=A graph showing evolution of number of nuclear weapons in the US and USSR and in the period 1945–2005. US dominates early and USSR later years with and crossover around 1978. Above-ground nuclear tests by the Soviet Union and the United States in the 1950s and early 1960s and by France into the 1970s and 1980s spread a significant amount of fallout from uranium daughter isotopes around the world. Additional fallout and pollution occurred from several nuclear accidents.
Contamination and the Cold War legacy thumb|U.S and USSR/Russian nuclear weapons stockpiles, 1945–2005|alt=A graph showing evolution of number of nuclear weapons in the US and USSR and in the period 1945–2005. US dominates early and USSR later years with and crossover around 1978. Above-ground nuclear tests by the Soviet .Union and the United States in the 1950s and early 1960s and by France into the 1970s and 1980s spread a significant amount of fallout from uranium daughter isotopes around the world. Additional fallout and pollution occurred from several nuclear accidents.