BIOLOGICAL EFFECTS OF RADIATION

biological effects of radiation

1. INTEGRAL UNIVERSITY , LUCKNOW FACULTY OF PHARMACY Guided By :- Prepared By :- Dr. Badruddeen Abu Raihan Shams Associate Professor(Jr. Pharm. D , 2 nd 1700100350

2. TOPIC BIOLOGICAL EFFECTS OF RADIATION

3. Radiation Radiation can be defined as the transmission of energy from a body in the form of waves or particles. Examples include heat or light from the sun, microwaves from an oven, X rays from an x-ray tube, and gamma rays from radioactive elements

4. Radiation is not only emitted during radiation therapy, but also from microwaves, cell phones, computers, and so on. Radiation is a type of energy that occurs naturally and can even be man-made. When the radiation is from the Sun or outer space, then it is called cosmic radiation , and when it comes from minerals in the Earth it is called terrestrial radiation . 13% of all radiation present is man-made. 12% is produced by X-ray and MRI machines, and 1% is produced by nuclear industries. Man-made radiation is more harmful as compared to natural ones because it is more concentrated.

5. Types of Radiation Radiation is often categorized as either ionizing or non-ionizing depending on the energy of the radiated particles. ( On the basis of energy of radiated particles )

6. Ionizing Radiation Ionizing radiation is radiation that carries enough energy to detach electrons from atoms or molecules, thereby ionizing them Ionizing radiation carries more than 10 eV energy, which is enough to ionize atoms and molecules, and break chemical bonds. Ionizing radiation consisting of particles, X-rays, or gamma rays with sufficient energy to cause ionization in the medium through which it passes.

7. Non-ionizing Radiation Non-ionizing radiation refers to any type of electromagnetic radiation that does not carry photon energy to ionize atoms or molecules. Non-ionizing radiation consists of electric & magnetic fields, UV rays, infrared, Laser rays ,Microwave ,Ultrasound waves.

8. Mechanism of action There are two theories exist to understand the mechanism of action. Target theory Indirect action theory

9. Target theory This theory proposes that radiant energy acts by direct hits on target molecules within the cells e.g. DNA. This can lead to Mutation, Genetic or Cancerous predisposition, Inhibition of cell division, Cell death, Damage to cell membrane or enzymes. Radiant energy, charged particles cause injury with this method.

10. Indirect action theory This theory proposes that the radiant energy exerts its effect by producing free radicals within the cells e.g. H°, OH-, H2O2, HO2. There free radicals may interact with them and can cause damage to cell membrane, nucleic acids, enzymes and even may cause cell death. Radiant energy, gamma and X-rays act by this mechanism.

11. Biological effects of Radiation The harmful effects caused to human beings and other living beings due to their exposure to radiation is called as biological effects of radiation. High radiation doses tend to kill cells, while low doses tend to damage or alter the genetic code (DNA) of irradiated cells.

12. Biological effects of radiation on living cells may result in three outcomes: Injured or damaged cells repair themselves, resulting in no residual damage Cells die, much like millions of body cells do every day, being replaced through normal biological processes; or Cells incorrectly repair themselves resulting in a biophysical change.

13. Some tissues and tumors are more sensitive to radiation than other. Sensitive tissues: - Lymphoid, hemopoietic , spermatogonic , ovarian follicle. Sensitive tumors : - Leukaemia, lymphoma, seminoma , dysgerminoma , Resistant tissues: - Bones, cartilage, muscles, peripheral nerves. Resistant tumors : - gliomas , sarcomas, melanoma, osteosarcoma .

14. Effects of Radiation on Cells Biological effect begins with the ionization of atoms. The mechanism by which radiation causes damage to human tissue, or any other material, is by ionization of atoms in the material. Ionizing radiation absorbed by human tissue has enough energy to remove electrons from the atoms that make up molecules of the tissue. ( Ionizing radiation )

15. The following are possible effects of radiation on cells: Cells are undamaged by the dose : - Ionization may form chemically active substances which in some cases alter the structure of the cells. These alterations may be the same as those changes that occur naturally in the cell and may have no negative effect. Cells are damaged, repair the damage and operate normally : - Some ionizing events produce substances not normally found in the cell. These can lead to a breakdown of the cell structure and its components. Cells can repair the damage if it is limited. Even damage to the chromosomes is usually repaired. After this cell operate normally. Contin ....

16. Cells are damaged, repair the damage and operate abnormally : - If a damaged cell needs to perform a function before it has had time to repair itself, it will either be unable to perform the repair function or perform the function incorrectly or incompletely. The result may be cells that cannot perform their normal functions or that now are damaging to other cells. These altered cells may be unable to reproduce themselves or may reproduce at an uncontrolled rate. Such cells can be the underlying causes of cancers. Cells die as a result of the damage : - If a cell is extensively damaged by radiation, or damaged in such a way that reproduction is affected, the cell may die. Radiation damage to cells may depend on how sensitive the cells are to radiation. Contin ....

17. Selective inhibition of cell proliferation is the most important effect Damage ot cytoplasmic enzymes, macromolecules and organelles Damage to DNA may lead to: - ➢ Oncogenic transformation ➢ Heritable genetic defect to children

18. Effects on organs and systems of body Dose of radiation Acute radiation dose An acute radiation dose is defined as a large dose (10 rad or greater, to the whole body) delivered during a short period of time (on the order of a few days at the most). If large enough, it may result in effects which are observable within a period of hours to weeks. Acute doses can cause a pattern of clearly identifiable symptoms (syndromes). These conditions are referred as Acute Radiation Syndrome .

19. Blood‐forming organ (Bone marrow) syndrome :-(>100 rad ) is characterized by damage to cells that divide at the most rapid pace (such as bone marrow, the spleen and lymphatic tissue). Symptoms include internal bleeding, fatigue, bacterial infections, and fever. Gastrointestinal tract syndrome :-(>1000 rad ) is characterized by damage to cells that divide less rapidly (such as the linings of the stomach and intestines). Symptoms include nausea, vomiting, diarrhea , dehydration, electrolytic imbalance, loss of digestion ability, bleeding ulcers, and the symptoms of blood‐forming organ syndrome.

20. CNS Syndrome :-(>5000 rad ) is characterized by damage to cells that do not reproduce such as nerve cells. Symptoms include loss of coordination, confusion, coma, convulsions, shock, and the symptoms of the blood forming organ and gastrointestinal tract syndromes.

21. Other effects from an acute dose include ➢ 200 to 300 rad to the skin can result in the reddening of the skin ( erythema ), similar to a mild sunburn and may result in hair loss due to damage to hair follicles. ➢ 125 to 200 rad to the ovaries can result in prolonged or permanent suppression of menstruation in about fifty percent (50%) of women. ➢ 600 rad to the ovaries or testicles can result in permanent sterilization. ➢ 50 rad to the thyroid gland can result in benign (non-cancerous) tumors .

22. Chronic Radiation dose A chronic dose is a relatively small amount of radiation received over a long period of time. The body is better equipped to tolerate a chronic dose than an acute dose. The body has time to repair damage because a smaller percentage of the cells need repair at any given time. The body also has time to replace dead or non‐functioning cells with new healthy cells. This is the type of dose received as occupational exposure.

23. Some radiation changes are as follows: - i ) Skin ➢ Post irradiation erythema (2-3 days) ➢ Post radiation edema (2-3 weeks) ➢ Epithelial blistering (4-6 weeks) ➢ Chronic radiodermatitis (Months / years) ➢ Skin cancers (years) ii) Hemopoietic and lymphoid tissue ➢ Severe lymphopenia ➢ Severe neutropenia ➢ Bone morrow depression

24. iii) Lungs ➢ Fatal respiratory failure ➢ Marked pulmonary edema ➢ Radiation pneumonitis iv) Gastrointestinal tract ➢ Loss of appetite, nausea, vomiting, diarrhoea ➢ Intestinal mucosal edema , hyperaemia, Ulcerations ➢ Intestinal mucosal atrophy, fabrosis . v) Brain It is relatively radioresistant in adult males. It shows focal necrosis only with high doses of radiations.

25. Dose Effects 10-50 rads No obvious effects 50-100 rads Vomiting, Nausea, Fatigue, lymphopenia , Neutropenia . 100-200 rads Vomiting, Nausea. 200-350 rads Severe gastrointestinal syndrome 350-550 rads GI+ Haeopoietic syndromes Death in 50% cases 550-750 rads 100% deaths in 6 months 1000 rads Death within days 5000 rads Death within hours to days Dose wise effects of radiations are as follows

26. Effects of Non-ionizing Radiation Laser rays: It may cause damage to lens, bone marrow, endocrine glands and DNA. Microwave: thermal injuries , painful burn , cataracts(due to exposure of high level of microwaves on eye) Ultrasound waves: It may alter nerve transmission. *****

27. REFERENCES Dr. Prakash S. Ghadi , Pathophysiology , career publication (Division of Career Consultants, Nashik ), page no: - 166-170. www.who.int/ionizing_radiation/about/what_is_ir/en/index.html. http://www.srmuniv.ac.in/sites/default/files/downloads/BI OLOGICAL_EFFECTS_OF_RADIATION.pdf Christensen DM, Iddins CJ, Sugarman SL (February 2014). "Ionizing radiation injuries and illnesses". Emerg Med Clin North Am. Page no: 245–65. All, E J (1 May 1976). "Radiation and the single cell: the physicist's contribution to radiobiology". Physics in Medicine and Biology. Page no: 347–359.