|
Radiation Safety |
TOPIC |
PAGE |
| Radiological Safety at TAMU | 16-2 |
| Radioactive Materials | 16-2 |
| Lasers | 16-3 |
| Magnets | 16-5 |
| Microwaves | 16-6 |
| Radiation-Producing Devices | 16-7 |
| Ultraviolet Lamps | 16-7 |
TAMU maintains strict requirements for working with sources of radiation. The radiation safety program at TAMU protects employees, students, and visitors as well as the public and the environment from the harmful effects of exposure to ionizing and nonionizing radiations. The Environmental Health & Safety Department (EHSD) governs the protocol and use of radioactive materials and radiation-producing devices on campus. Any faculty or staff member who desires to work with radioisotopes or radiation-producing devices must apply for and receive a permit from the EHSD. In addition, their employees and other employees who work with sources of radiation must receive formal training in equipment operation, safety guidelines, and emergency procedures.
The "Radiological Safety Program Procedure Manual" is available from the EHSD. It is divided into the following parts:
Radioactive Materials
The purpose of the Procedure Manual for the Use of Radioactive Materials is to establish the policies of TAMU with regard to the use of licensed radioactive materials. These policies apply to sealed sources as well as to open isotopes regardless of physical or chemical form.
Lasers
The State of Texas regulates the use of lasers through the Bureau of Radiation Control (BRC), Texas Department of Health. The TAMU Environmental Health & Safety Department registers, and is responsible for, the safe use of all lasers on campus.
Lasers present many safety threats, but the most common threat is damage to the eyes. Other common laser concerns include skin damage, electrical hazards from high-energy power sources, chemical exposure, fire/explosion hazards, and exposure to cryogenic materials such as hydrogen and oxygen. Many lasers emit invisible ultraviolet or infrared radiation.
Lasers are classified into four basic categories as indicated below:
Lowest power lasers that do not emit hazardous levels
Low-power lasers that pose a
hazard only if viewed directly for extended periods
Medium-power lasers that pose
moderate risk and can cause injury
High-energy, high-risk lasers
that can cause injury to the eyes and skin from direct or
diffused reflection
NOTE:
If you work with a class 3 or 4 laser, you must obtain a Laser Permit from the
Environmental Health & Safety Department.
Laser devices require engineering controls to ensure safety. All Class 3 and 4 lasers require a combination of protective housing, area warning signs or remote firing capabilities.
The following information is required for obtaining a laser permit:
Follow these guidelines when working with Class 3 and 4 lasers:
Magnets
The information in this section pertains only to large magnets at TAMU such as those used for magnetic resonance imaging.
Because the magnetic flux lines (or pull) from the main magnetic field can extend well beyond the actual magnet, the greatest hazard associated with large magnets is the missile effect. Ferromagnetic objects such as pens, scissors, screwdrivers, oxygen cylinders, and other metallic devices can be pulled into the magnet with enough force to cause a serious injury or accident. In addition, magnetic fields may also disrupt pacemakers or cause injury to individuals with surgically implanted metal pins or plates.
IMPORTANT:
To protect bystanders and prevent the accidental introduction of ferromagnetic
materials within the proximity of a magnet, establish a security zone around any large
magnet.
Microwaves
Microwaves are part of the electromagnetic spectrum; they range in frequency from 300 megahertz (MHz) to 300 gigahertz (GHz). Microwaves are used for communications, radar, intrusion alarms, door openers, and medical therapy, but they are most commonly used for cooking.
Metal reflects microwave radiation, but dry nonmetallic surfaces allow microwaves to pass through with little or no heating effect. Organic materials, however, are extremely heat conductive. Because microwaves can penetrate organic materials, including tissues, thermal burns and other effects may result from microwave exposure.
NOTE:
Microwave ovens are very safe when kept in good working condition and used properly. They do not serve as a source of exposure to harmful microwaves.
Even though microwave ovens are not a source of harmful radiation exposure, they should be properly used and maintained.
Radiation-Producing Devices
Radiation-producing devices such as X-ray machines, electron microscopes, and particle accelerators are regulated through the BRC, Texas Department of Health. All radiation-producing devices must be registered with the TAMU Environmental Health & Safety Department.
Radiation-producing devices (other than human and veterinary diagnostic devices) shall be interlocked to prevent access to the unshielded beam during normal or routine operations. Exceptions may be granted by the TAMU Radiological Safety Committee.
IMPORTANT:
The door(s) to a room where a radiation-producing device is located should be posted
with a radiation warning sign, unless the device is totally self-contained.
Ultraviolet Lamps
Ultraviolet (UV) lamps are useful germicidal tools, but they also pose a potential
health hazard. The following sections provide essential safety information for working
with UV lamps and light.
Exposure to UV radiation can cause extreme discomfort and serious injury. Therefore, you must protect your eyes and skin from direct and reflected UV light. Pay particular attention to laboratory surfaces, such as stainless steel, that can reflect UV light and increase your UV exposure.
The effect of UV radiation overexposure depends on UV dosage, wave length, portion of body exposed, and the sensitivity of the individual. Overexposure of the eyes may produce painful inflammation, a gritty sensation, and/or tears within three to twelve hours. Overexposure of the skin will produce reddening (i.e., sunburn) within one to eight hours. Certain medication can cause an individual to be more reactive to UV light.
Adequate eye and skin protection are essential when working around UV radiation. Before entering a laboratory with ultraviolet installations, you must turn off the lights or wear protective equipment (e.g., goggles, cap, gown, and gloves).
NOTE:
Safety glasses with side shields or goggles with solid side pieces are the only
equipment that provide adequate eye protection against direct and reflected UV light.
Germicidal Function
UV radiation is particularly useful in the laboratory when combined with other methods for decontamination and disinfection. UV radiation is used primarily to reduce the number of microorganisms in the air and on surfaces. It is most effective against vegetative bacteria.
UV rays can only kill organisms that are invisible to the naked eye. To be effective, UV rays must directly strike the microorganisms. If microorganisms are shielded by a coating of organic material (e.g., culture medium), the UV light will be ineffective.
Ultraviolet lamps lose germicidal effectiveness over time and may need to be replaced even though the lamp has not burned out. It may be necessary to replace the lamp according to the manufacturer's recommendations. There are two types of UV lamps – hot cathode and cold cathode. The hot cathode lamp has two pins at each end, and the cold cathode lamp has one pin at each end. Manufacturers recommend that hot cathode lamps be replaced every six months and that cold cathode lamps be replaced every 12 months.
In addition to replacing UV lamps as indicated above, follow these guidelines to maintain UV lamps: