Stumper426
Member
Since World War II, many significant technological advancements have occurred within the telecommunications and other industries. One of these is the increased use of microwave and radio frequency (radiation) equipment. Such equipment is widely used in the broadcasting and communications fields in the form of cellular telephones and towers; in the health care industry for medical treatment; in the in the food industry for the processing and cooking of food; in wood, textile, and glass fiber industries for drying materials; and in the rubber and plastic products industries for fusing and sealing operations.
The National Institute for Occupational Safety and Health (NIOSH) estimates that millions of American workers work with and are exposed to microwave and radio frequency radiation equipment. CWA members who are exposed to microwave and radio frequency radiation include microwave and radio frequency service technicians, operators of computers, employees who use microwave ovens at work, radio frequency radiation equipment operators, and workers who come in contact with, or who operate medical diathermy equipment.
Microwave and radio frequency radiation are two components of the electromagnetic spectrum (see Tables). As noted in Table 1 (Table 1 not available in web version of Fact Sheet), microwave and radio frequency radiation are in the non-ionizing portion of the spectrum. Non-ionizing radiation includes the lower frequencies in the electromagnetic spectrum such as ultra violet and visible light, infrared, microwave and radio frequency.
Electromagnetic radiation consists of vibrating electric and magnetic fields moving through space. For example, electric current in a transmitter circuit establishes magnetic and electric fields in the region around it. As the electric current moves back and forth, the fields continue to build up and collapse, forming electromagnetic radiation. This electromagnetic radiation is described in terms of the wavelength or the frequency of vibration.
Microwave and radio frequency radiation may be categorized as continuous waves (e.g., communications equipment), intermittent (microwave ovens, medical diathermy equipment, and radio frequency equipment), or pulsed mode (radar systems). Microwave and radio frequency radiation may be transmitted, reflected, or absorbed upon striking an object.
When measuring radiation emissions, the power of the source should be measured by the intensity of the beam. Intensity should be measured in terms of power density. Power density is the amount of energy carried by microwave or radio frequency radiation as it proceeds each second through a square measure of space. The energy carried by microwave and radio frequency radiation is expressed in terms of watts (W), milliwatts (mW - 1/1,000 of a watt), or microwatts (uW - 1/1,000 of a milliwatt).
Health Effects
The various types of radiation (refer to Tables) affect the human body in different ways. For example, ionizing radiation which contains a tremendous amount of energy and penetrating power will cause changes in the body's molecular system. On the other hand, as noted, non-ionizing radiation operates at much lower frequencies and, given current scientific opinion, is not believed to be as harmful to the human body as ionizing radiation. The type of radiation to which CWA members are most often exposed is non-ionizing radiation, e.g., microwave and radio frequency radiation.
It is known, however, that exposure to non-ionizing microwave and radio frequency radiation may produce serious biological effects. As microwave and radio frequency radiation penetrates the body, the exposed molecules move about and collide with one another causing friction and, thus, heat. This is known as thermal effect. If the radiation is powerful enough, the tissue or skin will be heated or burned. Such health effects may or may not be reversible, depending on the particular tissue or organ that is exposed, the intensity of the radiation, the frequency and duration of the exposure, and the environmental temperature and humidity.
Exposure to microwave and radio frequency radiation may also may result in a nonthermal reaction which causes molecular interactions as in the thermal effect, but without heating of the exposed tissue or organ. The site of energy absorption varies with the frequency, that is, exposure to low frequency non-ionizing radiation will penetrate the skin and heat the underlying tissues to a greater degree than exposure to high frequency non-ionizing radiation. In addition, the body's heat and paid warning system may not provide protection because the energy is absorbed at locations below the nerves.
At the present time, there is substantial scientific data that establishes negative health effects associated with exposure to microwave radiation. On the other hand, less data is available that establishes links with radio frequency radiation and health effects.
It has been demonstrated that microwave radiation may cause eye and testicular (reproductive) damage. These organs are highly vulnerable to radiation damage because they contain few blood vessels; therefore, they are unable to circulate blood and dissipate the heat from radiation as effectively as other organs. Several scientific investigations have shown that human and laboratory animal cataracts may be caused by intense heating of high frequency microwave radiation. Intervals between such exposure are an important factor since the body's repair mechanism acts to limit lens damage if an adequate time has elapsed between exposures.
As mentioned, scientists believe that high frequency microwave radiation may cause eye damage (cataracts). However, there is no such agreement regarding exposure to low frequency microwave radiation. Microwave radiation may also cause damage to male reproductive organs. Specifically, scientists have demonstrated that exposure may result in partial or permanent sterility. In addition, some scientific evidence exists which suggests concern about the reproductive effects in women, as well as men.
Furthermore, the scientific literature suggests a relationship between exposure to microwave radiation and birth defects, such as mongolism (Down's Syndrome) and central nervous system damage. Clearly, a review of the medical and scientific literature indicates a tremendous need for more scientific research. Such research should more accurately indicate the effects of microwave and radio frequency radiation upon humans. Particular emphasis needs to be directed at exposure to long-term, low-level biological effects of microwave and radio frequency radiation. Such research is particularly important in order that the issue of potentially harmful microwave radiation emissions from microwave and radio frequency transmitters might be more adequately resolved.
An additional healthy concern regarding work with radio frequency equipment is potential electrical shock. This may occur when, under abnormal conditions, the operator is standing in water and comes into contact with a high-frequency generator circuit.
Controlling the Hazard
Employers must ensure that potentially exposed microwave and radio frequency radiation workers have a safe and healthful workplace. This means using engineering controls to minimize or eliminate potential exposure, conducting comprehensive training about the potentially hazardous working conditions, and instituting medical surveillance programs.
The most effective way to eliminate and/or minimize occupational exposure to microwave and radio frequency radiation is through the use of engineering controls. For example, the source of the potential problem, i.e., the radiation-emitting equipment, should be enclosed or effectively shielded or the worker should be separated from the source. This requirement is equally important to all workers exposed to microwave and radio frequency radiation.
In addition, employers should provide comprehensive training regarding potentially hazardous working conditions. Such a program might consist of written and/or audio/visual materials that detail potential safety and health dangers, health effects of exposure, methods of control, first aid procedures, and the use of hazard warning signs and labels and the identification of restricted areas.
Employers should also institute medical surveillance programs which would provide workers with routine medical examinations specific to any biological effects resulting from occupational exposures. Potential benefits of medical surveillance would include: an assessment of employees' physical fitness to safely perform the work (this would consist of a medical and occupational history and physical examination), biological monitoring of exposure to a particular agent, early detection of any biological damages or effects, and information for possible epidemiological research (the study of diseases). In addition, documented health effects would allow the worker and his/her physician to make informed judgements about further exposures.
The OSHA Standard
The OSHA Standard for electromagnetic radiation (includes microwave and radio frequency radiation) is 10 Mw/cm2 (milliwatt per square centimeter) as averaged over any possible 0.1 hour period. This means the following:
Power Density: 10mW/cm2 for periods of 0.1 hour or more.
Energy Density: 1mWh/cm2 (milliwatt hour per square centimeter) during any 0.l hour period.
The Standard is based upon research conducted in 1953 examining the threshold for thermal (heat) damage to tissue (specifically), the amount of radiation that would cause cataract development). The power density necessary to produce cataracts was approximately 100 Mw/cm2 to which a safety factor of 10 applied. Thus, a maximum permissible level of 10mW/cm2 was established.
Presently, several governmental and professional organizations such as the National Institute for Occupational Safety and Health (NIOSH), the American National Standards Institute, the American Conference of Governmental Industrial Hygienists, the American Industrial Hygiene Association, and labor organizations (including CWA) are lobbying for and/or conducting scientific investigations to determine whether a more stringent standard needs to be established.
The National Institute for Occupational Safety and Health (NIOSH) estimates that millions of American workers work with and are exposed to microwave and radio frequency radiation equipment. CWA members who are exposed to microwave and radio frequency radiation include microwave and radio frequency service technicians, operators of computers, employees who use microwave ovens at work, radio frequency radiation equipment operators, and workers who come in contact with, or who operate medical diathermy equipment.
Microwave and radio frequency radiation are two components of the electromagnetic spectrum (see Tables). As noted in Table 1 (Table 1 not available in web version of Fact Sheet), microwave and radio frequency radiation are in the non-ionizing portion of the spectrum. Non-ionizing radiation includes the lower frequencies in the electromagnetic spectrum such as ultra violet and visible light, infrared, microwave and radio frequency.
Electromagnetic radiation consists of vibrating electric and magnetic fields moving through space. For example, electric current in a transmitter circuit establishes magnetic and electric fields in the region around it. As the electric current moves back and forth, the fields continue to build up and collapse, forming electromagnetic radiation. This electromagnetic radiation is described in terms of the wavelength or the frequency of vibration.
Microwave and radio frequency radiation may be categorized as continuous waves (e.g., communications equipment), intermittent (microwave ovens, medical diathermy equipment, and radio frequency equipment), or pulsed mode (radar systems). Microwave and radio frequency radiation may be transmitted, reflected, or absorbed upon striking an object.
When measuring radiation emissions, the power of the source should be measured by the intensity of the beam. Intensity should be measured in terms of power density. Power density is the amount of energy carried by microwave or radio frequency radiation as it proceeds each second through a square measure of space. The energy carried by microwave and radio frequency radiation is expressed in terms of watts (W), milliwatts (mW - 1/1,000 of a watt), or microwatts (uW - 1/1,000 of a milliwatt).
Health Effects
The various types of radiation (refer to Tables) affect the human body in different ways. For example, ionizing radiation which contains a tremendous amount of energy and penetrating power will cause changes in the body's molecular system. On the other hand, as noted, non-ionizing radiation operates at much lower frequencies and, given current scientific opinion, is not believed to be as harmful to the human body as ionizing radiation. The type of radiation to which CWA members are most often exposed is non-ionizing radiation, e.g., microwave and radio frequency radiation.
It is known, however, that exposure to non-ionizing microwave and radio frequency radiation may produce serious biological effects. As microwave and radio frequency radiation penetrates the body, the exposed molecules move about and collide with one another causing friction and, thus, heat. This is known as thermal effect. If the radiation is powerful enough, the tissue or skin will be heated or burned. Such health effects may or may not be reversible, depending on the particular tissue or organ that is exposed, the intensity of the radiation, the frequency and duration of the exposure, and the environmental temperature and humidity.
Exposure to microwave and radio frequency radiation may also may result in a nonthermal reaction which causes molecular interactions as in the thermal effect, but without heating of the exposed tissue or organ. The site of energy absorption varies with the frequency, that is, exposure to low frequency non-ionizing radiation will penetrate the skin and heat the underlying tissues to a greater degree than exposure to high frequency non-ionizing radiation. In addition, the body's heat and paid warning system may not provide protection because the energy is absorbed at locations below the nerves.
At the present time, there is substantial scientific data that establishes negative health effects associated with exposure to microwave radiation. On the other hand, less data is available that establishes links with radio frequency radiation and health effects.
It has been demonstrated that microwave radiation may cause eye and testicular (reproductive) damage. These organs are highly vulnerable to radiation damage because they contain few blood vessels; therefore, they are unable to circulate blood and dissipate the heat from radiation as effectively as other organs. Several scientific investigations have shown that human and laboratory animal cataracts may be caused by intense heating of high frequency microwave radiation. Intervals between such exposure are an important factor since the body's repair mechanism acts to limit lens damage if an adequate time has elapsed between exposures.
As mentioned, scientists believe that high frequency microwave radiation may cause eye damage (cataracts). However, there is no such agreement regarding exposure to low frequency microwave radiation. Microwave radiation may also cause damage to male reproductive organs. Specifically, scientists have demonstrated that exposure may result in partial or permanent sterility. In addition, some scientific evidence exists which suggests concern about the reproductive effects in women, as well as men.
Furthermore, the scientific literature suggests a relationship between exposure to microwave radiation and birth defects, such as mongolism (Down's Syndrome) and central nervous system damage. Clearly, a review of the medical and scientific literature indicates a tremendous need for more scientific research. Such research should more accurately indicate the effects of microwave and radio frequency radiation upon humans. Particular emphasis needs to be directed at exposure to long-term, low-level biological effects of microwave and radio frequency radiation. Such research is particularly important in order that the issue of potentially harmful microwave radiation emissions from microwave and radio frequency transmitters might be more adequately resolved.
An additional healthy concern regarding work with radio frequency equipment is potential electrical shock. This may occur when, under abnormal conditions, the operator is standing in water and comes into contact with a high-frequency generator circuit.
Controlling the Hazard
Employers must ensure that potentially exposed microwave and radio frequency radiation workers have a safe and healthful workplace. This means using engineering controls to minimize or eliminate potential exposure, conducting comprehensive training about the potentially hazardous working conditions, and instituting medical surveillance programs.
The most effective way to eliminate and/or minimize occupational exposure to microwave and radio frequency radiation is through the use of engineering controls. For example, the source of the potential problem, i.e., the radiation-emitting equipment, should be enclosed or effectively shielded or the worker should be separated from the source. This requirement is equally important to all workers exposed to microwave and radio frequency radiation.
In addition, employers should provide comprehensive training regarding potentially hazardous working conditions. Such a program might consist of written and/or audio/visual materials that detail potential safety and health dangers, health effects of exposure, methods of control, first aid procedures, and the use of hazard warning signs and labels and the identification of restricted areas.
Employers should also institute medical surveillance programs which would provide workers with routine medical examinations specific to any biological effects resulting from occupational exposures. Potential benefits of medical surveillance would include: an assessment of employees' physical fitness to safely perform the work (this would consist of a medical and occupational history and physical examination), biological monitoring of exposure to a particular agent, early detection of any biological damages or effects, and information for possible epidemiological research (the study of diseases). In addition, documented health effects would allow the worker and his/her physician to make informed judgements about further exposures.
The OSHA Standard
The OSHA Standard for electromagnetic radiation (includes microwave and radio frequency radiation) is 10 Mw/cm2 (milliwatt per square centimeter) as averaged over any possible 0.1 hour period. This means the following:
Power Density: 10mW/cm2 for periods of 0.1 hour or more.
Energy Density: 1mWh/cm2 (milliwatt hour per square centimeter) during any 0.l hour period.
The Standard is based upon research conducted in 1953 examining the threshold for thermal (heat) damage to tissue (specifically), the amount of radiation that would cause cataract development). The power density necessary to produce cataracts was approximately 100 Mw/cm2 to which a safety factor of 10 applied. Thus, a maximum permissible level of 10mW/cm2 was established.
Presently, several governmental and professional organizations such as the National Institute for Occupational Safety and Health (NIOSH), the American National Standards Institute, the American Conference of Governmental Industrial Hygienists, the American Industrial Hygiene Association, and labor organizations (including CWA) are lobbying for and/or conducting scientific investigations to determine whether a more stringent standard needs to be established.
