By Helen Regan, CNN
(CNN)Radiation levels across parts of the Marshall Islands in the Pacific Ocean, where the United States tested nuclear bombs during the Cold War, are higher than areas contaminated by the Chernobyl and Fukushima nuclear disasters, new research suggests.
From 1946 to 1958, the US government conducted 67 nuclear tests on several small islands — called atolls — in the Marshall Islands.
The US government relocated entire populations and exposed others to cancer and disease-causing radiation.
More than 60 years later, researchers at Columbia University say radiation on four of these atolls remains alarmingly high — in some areas ten to 1,000 times higher than radioactive areas near the Chernobyl powerplant, which exploded in 1986, and Fukushima, where an earthquake and tsunami caused a nuclear disaster in 2011.
