Effects of Radiation Exposure on Human Blood Forming Organs

          Radioactive are unstable atoms whose nucleus change or decay by spitting out radiation, which is in the form of particles or electromagnetic waves. Radiation can kill living cells or change the nature of living cells. Since all living things contain living cell, whether the radiation is large dose or low dose, naturally occur or manmade, it can be bring some biological effects to human body. Among all organs in the body, the organ mostly get affected by radiation from radioactive process is blood-forming organ. 

          Blood forming organ is an organ that synthesizes blood cell such as erythrocytes, leukocyte and platelets. The examples of blood forming organs are spleen and bone marrow. Blood forming organs are the most sensitive organs to radiation due to its rapid regeneration time. When blood forming organs are exposed to the radiation from radioactive component, early lethal effects that appear is hematopoietic syndrome. Hematopoietic syndrome presents due to ionizing radiation impairs hematopoiesis through a variety of mechanisms. Ionizing radiation exposures directly damages the hematopoietic stem cells and affects bone marrow in maintaining or supporting hematopoiesis in vivo and in vitro. Hematopoietic syndrome could cause death when body exposure at radiation doses <8 Gy (1 Gy = 1 Joule/Kg). Peak incidence of death occurs at about 30 day’s post- irradiation and also continues for up to 60 days. Exposure to ionizing radiation causes normal bone marrow and also spleen functions to be suppress with redistribution and apoptosis of mature formed elements of the blood. Symptoms that usually are associated with hematopoietic syndrome are fatigue, internal bleeding, bacterial infections, fever, ulceration or anaemia. Death normally occurs unless receive bone marrow transplant. 

         

          Disease that is associated with blood forming organs caused by ionizing radiation exposure is leukemia.  Leukemia is a cancer of white blood cells that begins in the bone marrow. When leukemia develops, it leads to an uncontrolled increase in the number of leukocytes. An increase in the number of leukocytes in human body can prevent healthy erythrocyte, platelets and mature leukocytes from being made. During the Second World War, two atomic bombs were dropped on Hiroshima and Nagasaki in Japan, there were 176 leukemia deaths among 50,113 survivors with significant exposures (>0.5 Gy). It was estimated that about 90 of these death are associated with radiation exposure. Symptoms that are associated with leukemia are anemia, bleeding, weight loss, night sweats, fever and easy bruising.