Atomic bomb test. Aerial view of the explosion of an atomic bomb at the test site in Nevada, USA. The explosion has the typical 'mushroom cloud' appearance. Atomic bomb tests were started at Nevada in 1951. Downwind from the test sites the incidence of leukaemia rose sharply in the following years as did the amount of miscarriages and congenital abnormalities. These tragedies raised the public awareness of the hazards of radiation. This led to the banning of atmospheric nuclear bomb tests in the mid-1960s. Continued research into the effects of radiation led to a complete ban on tests being approved by the United Nations in 1996.