Living and Dying Downwind  The unleashed isotopes of concern from the damaged Japanese reactors - Iodine-131, Cesium-137, Strontium-90 and Plutonium-239 - are well known to the Marshall Islanders living downwind of the testing sites at Bikini and Enewetak atolls in the central Pacific, following sixty-seven A- and H-bombs exploded between 1946-58.