Recognizing Radiation Sickness The difficulty with radiation exposure is that symptoms will appear anywhere from a few minutes to twenty years after exposure. The timing depends on the type of radiation, the dosage, and the part of the body exposed. The two basic categories are nonionizing (which is benign) and ionizing (which is harmful). The benign category includes light, radio waves, microwaves, and radar. Ionizing radiation produces immediate chemical effects on human tissue. The basic types are x-rays, gamma rays, and particle bombardment (neutron beam, electron beam, protons, mesons, and others). Producers of radioactive materials have distributed them throughout the world for a variety of peaceful and military uses, including medical testing and treatment, electrical power, industrial testing, manufacturing, sterilization, submarine power source, and weapons.   Radiation sickness results from exposure to excessive doses of ionizing radiation. Illness-producing exposure can occur from a single large dose (acute) or a series of small doses spread over time (chronic). Acute exposure usually results in illness linked to a characteristic set of symptoms that usually appear in a specific sequence. Chronic exposure usually results in a delayed reaction (often by many years) causing medical problems such as leukemia, other cancers, and premature aging.   The severity of symptoms and illness from radiation depends on the type, the amount, the duration, length of exposure, and the body areas exposed. Symptoms of radiation sickness usually do not occur immediately following exposure. Doctors often use the time lapsed between exposure and onset of symptoms to determine what to expect in terms of severity.   The initial symptoms are nausea, vomiting, diarrhea, and fatigue. The next onset of symptoms may include the following: headache shortness of breath rapid heartbeat inflammation of the mouth and throat inflammation of teeth (internally) or gums hair loss dry cough heart inflammation with chest pain appearance of second and third-degree burns permanent skin darkening multiple bruising all over the skin hemorrhage anemia secondary infection of burn areas