JOHN LAFORGE – There is no safe level of exposure to ionizing radiation, only legally “allowable†doses. Types of ionizing radiation include gamma rays, beta and alpha particles, and X-rays emitted by radioactive elements — like the iodine-131, cesium-137, strontium-90 and even plutonium-239 — that have been spewed into the air and the sea in huge quantities by the triple reactor meltdowns that began in Japan last year, and that are dispersed to the air, water and to dump sites in smaller amounts by the everyday operation of nuclear power and medicine.