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Sensitivity of body organs to radiation

Gonad: The probability of cancer induction in this organ is comparatively low. The main concern is the genetic effects due to irradiation of this organ and the probability is proportional to the absorbed dose.
Red bone marrow: The effect on bone marrow plays an important role in the induction of leukemia. Based on statistical data from radiotherapy patients and atomic bomb survivors in Japan, the probability of leukemia is maximum at several years after the irradiation and will return to the normal incident level after about 25 years.
Bone: The radiosensitive cells in bone are endosteal cells and epithelial cells on the bone surfaces. The sensitivity of bone is less than that of the breast, red bone marrow, lung and thyroid.
Lung: Cancer of the lung has been observed in miners exposed to high concentration of radon and its decay products. External irradiation can also induce lung cancer and the risk is about the same as that for the development of leukemia.
Thyroid: Radiation can induce thyroid cancer. However, the mortality of this type of cancer is much lower than that of leukemia primarily because of the success in the treatment of thyroid cancer.
Breast: During reproductive life, the female breast may be one of the more radiosensitive tissues of the human body. The risk for breast cancer is about one half of that of leukemia.
Skin: The effects on skin depend on absorbed dose and the area of irradiation. Major effects are erythema and ulceration of the skin. The probability of induction of skin cancer is less than the above organs.
Lens: The effects of radiation on the eyes are causing cataract, which is the opacity of the lens. The lens is 5 to 10 times more sensitive to neutrons than to x-ray. Thresholds exist with lower values for children than those for the adults.
Fetus: Effects depend on the stage of pregnancy at the time of exposure. At the early stage of pregnancy when the cells are still not differentiated, it usually causes death of the embryo. It is generally believed that exposure of fetus at the first 3 weeks of pregnancy should not cause any deterministic and stochastic effect to the embryo. Later stage irradiation of the fetus may leads to malformation of body organs and increase in cancer risk of the child.


The above information is provided by RHU of DH
Department of Health

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Last revision date: <19 Dec 2012>