Essentials of Environmental Health PH 203 Dr. Khaled El-Ezaby Radiation Definition of Radiation: Radiation can be defined as energy released in the form of particles or electromagnetic waves.

Radiation in the Environment: Many forms of radiation are encountered in the natural environment and are produced by modern technology. Most of them have the potential for both beneficial and harmful effects. People know some kinds of radiation, such as X-rays, Gamma rays and radiation from nuclear reactors. These species usually described as harmful to health, although the X-rays and gamma rays have useful applications in medicine.

Even sunlight (ultraviolet rays), the most essential radiation of all, can be harmful in excessive amounts. In addition, there are many other forms of radiation, such as heat emitted from the fire, radio signals carrying the music, the intense laser light, and microwaves used in cooking.

Essentials of Environmental Health PH 203 Dr. Khaled El-Ezaby Types of Radiation: There are two basic types of radiation (See Figure 12.1 ‘The electromagnetic spectrum’*): 1- Ionizing radiation This radiation can disrupt atoms, creating positive ions and negative electrons, and cause biological harm. Ionizing radiation includes x-rays, gamma rays, alpha particles, beta particles, neutrons, and the varieties of cosmic rays. 2- Non-ionizing radiation Non-ionizing radiation such as electromagnetic radiation, including radio, television and radar waves, heat waves with short wavelengths (microwaves), infra red and ultraviolet radiations. Non-ionizing radiation ranges from extremely low frequency radiation, shown on the far left through the audible, microwave, and visible portions of the spectrum into the ultraviolet range. ______________________________________________________________________________________________________________ * Moeller, D. W., (2005). Environmental Health, 3rd. Ed., Page 296, Harvard University Press, USA.

Essentials of Environmental Health PH 203 Dr. Khaled El-Ezaby Some Benefits and Hazards of Ionizing Radiation: * Benefits - Radioactive materials and other sources of ionizing radiation are widely used to diagnose and treat diseases in human and veterinary medicine. Medical and dental X-rays are used to detect problems such as broken bones and dental cavities. Sealed radiation sources are used to deliver very high, localized radiation doses to treat certain types of cancers. - Radioactive sources are used to generate heat and electricity for space travel. * Hazards - All ionizing radiations, at sufficiently large exposures, can cause cancer and genetic and birth defects.

Causes of damage due to radiation: Damage happens when radiation interacts with oxygen, causing certain molecules to form in the body. These molecules can damage or break strands of DNA in cells. The cells may eventually die. Who is most at risk of radiation: People who have been exposed to radiation and who also have the following conditions or characteristics are at risk for developing radiation damage: . High dose of radiation exposure. . Young age at time of exposure. . Use of Chemotherapy and antibiotics. . Exposure to radiation before birth (while in the womb).