Chapter 14 - Radiation Hazards

Ionizing radiation is a form of energy. Unlike some other types of energy, such as heat (infrared radiation) or visible light, the human body cannot sense exposure to ionizing radiation. Nonetheless, absorption of ionizing radiation energy by body tissues causes changes to the chemical makeup of living cells.

The type and thickness of material needed to make an effective barrier or shield around a source of ionizing radiation varies a great deal depending on the type of ionizing radiation. Beta radiation is a stream of tiny charged particles that can be stopped by a thin layer of plastic, glass, wood, metal and most other common materials. X-rays and Gamma rays are very similar to sunlight in that they are not particles, just electromagnetic waves. While sunlight will pass through only a few materials, such as window glass, X-rays and Gamma rays penetrate easily through most materials. However, even they can be blocked by a sufficient thickness of lead.

Ionizing radiation is also similar to other forms of radiation in that the intensity of the radiation exposure decreases very quickly as you move away from the radiation source. Just as moving a short distance closer to or farther from a fireplace causes a large change in how warm you feel; keeping just a few feet away from where someone is handling radioactive material will almost eliminate your exposure.

Other Resources:

Cornell University Radiation Safety Manual
Disposal of Radioactive Materials
Cornell Radiation Safety Program

14.1 Where Ionizing Radiation is Used

Small amounts of radioactive material are used and stored in hundreds of laboratory rooms around the campus. Some of the material is contained in small sealed capsules. Examples of these “sealed sources” include test sources for radiation detectors and ionization detectors in gas chromatographs. Most often radioactive material is found in small vials of radioactively labeled chemicals in solution. These labeled chemicals are widely used in research and in veterinary medicine. With very few exceptions, only very small amounts of radioactive material are used and levels of radiation exposure are quite low.

Ionizing radiation can also be produced by certain electrical equipment, including X-ray machines and particle accelerators. There are approximately one hundred pieces of radiation producing equipment on the campus. Radiation levels produced by this equipment are also very low because of shielding.

You can tell if a room contains a source of ionizing radiation because each entrance is plainly marked by warning labels. Within the room, additional labels and warning tape will be found on each piece of radiation producing equipment and on all areas used to work with or store radioactive material.

14.2 Potential Hazards

Like any form of energy, ionizing radiation can be harmful if a person is exposed to an excessive amount. Exposure to ionizing radiation causes chemical damage to body tissues and can be harmful. Just as with exposure to any toxic chemical, the human body can tolerate exposure to ionizing radiation up to a point without producing any immediate injury. However, just as with toxic chemicals, high levels of exposure can cause serious injuries including skin burns, hair loss, internal bleeding, anemia and immune system suppression. In addition, exposure to high levels of ionizing radiation has been proven to cause an increased lifetime risk of cancer.

14.2.1 How to Protect Yourself

Responsibility for protecting themselves, co-workers and others from exposure to ionizing radiation is delegated by the Radiation Safety Committee to the Principal Investigator or area supervisor and to each of the individual users. Appropriate safety requirements, that are specific to each use and location, are written into each approval granted by the Committee. Every user is trained in radiation safety principles and on the specific safety requirements of their operations before they are allowed to begin working with radioactive material.

Other individuals in these areas, who are not trained to use radioactive material or radiation producing equipment, need to follow the safety procedures established for those working with ionizing radiation. Primarily this means:

Never operate equipment that produces ionizing radiation.
Never handle items or containers that are labeled with radioactive material warnings or that are within areas marked as storage or use areas for radioactive material.

14.3 Control of Ionizing Radiation

All use of material or equipment that produces ionizing radiation requires prior approval by the Cornell University Radiation Safety Committee. This group of faculty members set policies and personally reviews each operation to ensure safety and compliance with state and federal regulations. The University Radiation Safety Officer and the Radiation Safety Group within EHS provide training and other services to help individuals work safely. In addition, they perform routine inspections of all use areas and require correction of all violations of radiation safety requirements. Detailed information on the university radiation safety program is available in the Cornell University Radiation Safety Manual.

The performance of the Cornell Radiation Safety Program is reviewed continuously. The Radiation Safety Committee meets 4 times each year to keep policies up-to-date, resolve problems and compliance issues and to monitor the level of radiation exposure to individuals on campus. Historically, less than 1% of the individuals using ionizing radiation at Cornell receive more than 1% of the annual allowable dose limit. The Committee also audits EHS programs and services. In addition, the New York State Department of Health performs an on campus assessment of our program every two years.

The information presented here is only a brief overview of how sources of ionizing radiation are used at Cornell University. While Cornell has demonstrated that it has a solid and consistent safety program, it is important not to take safety for granted. If you have questions or concerns about the use of ionizing radiation where you work, you are entitled to answers and information. The Principal Investigator, area supervisor or any authorized user is willing and able to help you and you should feel free to speak with them. They understand that many individuals have never had formal training about radiation safety. If you need additional assistance or have any other questions, please contact EHS at 607-255-8200 or askEHS@cornell.edu.

14.4 Radioactive Waste Disposal

Radioactive material cannot be disposed of in the regular trash. Please see the Radioactive Waste page for procedures to prepare radioactive waste for collection by EHS. For more information or if you have any questions, please contact askEHS.