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HEALTH RISKS OF EMF:
FMS clients often ask our opinion on the relationship of exposure to EMF and human health risk. FMS does not have medical expertise and does not express a judgment or opinion regarding health risks; that is best left to competent scientific/medical researchers. These issues are very complex, and there remain many unanswered questions regarding EMF and human health risk.
The following statements and the content of this “Health Concern” section of FMS’ website are offered as a general resource. FMS encourages interested or concerned parties, to conduct their own research and develop an informed understanding of the issues. There is a tremendous amount of research material available on the WEB and elsewhere regarding EMF health risk research.
DC MAGNETIC FIELDS:
Generally, there are few human health concerns associated with static or DC magnetic fields, except at extremely high levels, exceeding 20 Gauss or 20,000 mG. There are however, a number of “safety” related concerns from elevated DC magnetic field levels including possible interference or failure of cardiac pacemakers, defibrillators, insulin pumps, or other medical implanted devices at levels in excess of 5,000 mG.
AC MAGNETIC FIELDS:
For the past 30+ years, concerns about human health risk and exposure to AC (50-60 Hz – power frequency) magnetic fields from transmission lines and other electrical sources, such as a building’s electrical distribution system, have been extensively researched, with generally conflicting or inconsistent results. Research continues on magnetic field exposure and possible increased risk of childhood leukemia, adult brain cancer, Lou Gehrig‘s disease, and miscarriages. Presently, in the United States, the U.S. National Institute of Environmental Health Sciences (NIEHS, 1999) Director has concluded that:
“The scientific evidence suggesting that [EMF] exposures pose any health risk is weak …[but they] cannot be recognized at this time as entirely safe because of weak scientific evidence that exposures may pose a weak leukemia hazard.”
HEALTH RISKS OF RF EXPOSURE:
For radio frequency (RF) EMF, there are long-standing issues such as possible human health risk from cell phone use, that continue to drive further investigation, as well as new concerns related to emerging wireless technologies. The virtual explosion of technology in wireless communications has opened new issues in worker exposure that are the subject of additional research. One of these issues is the concern related to RF radiation exposure of workers who build and maintain RF transmitting towers for both telecommunications and media broadcast stations.
Today, RF exposure is a matter of regulatory concern. The FCC under OET-65 mirrors IEEE standards. The World Health Organization has slightly more stringent standards for RF Exposure.
The genesis of the exposure standards come from animal behavioral studies.
There is no known mechanism through which RF can impact biological processes – other than through the generation of heat, and in very high fields, through RF electrical burns.
Early standards sought to define the level at which tissue heating becomes an issue.
Early research to support these standards involved finding a level of RF exposure in which observable behavior changes were recognized in animal subjects. This was determined through research and experimentation.
Researchers then incorporated a “safety factor” – a factor of 10 was applied to the levels at which animal behavior changes were observed. This is the level at which “Occupational” exposure levels are presently set.
To establish a “General Public” level, a further factor of 5 was applied to the Occupational levels.
Thus, the “General Public” RF exposure category is the level at which human exposure is 1/50th of the observed animal behavioral change.
Brief Note about Occupational/General Public exposure categories:
“Occupational” exposure category is the maximum level/duration at which a worker can be exposed to RF fields – given that they have “awareness” of the RF environment, and have some level of training so that they can limit their exposure that is unavoidable as a consequence of their work.
“General Public” exposure category is the maximum level/duration at which a member of the general public can be exposed to RF fields – given that they are unlikely to have any awareness of the exposure, have no formal training on avoiding RF exposure situations, and therefore cannot avoid RF exposure.
The final aspect of the RF exposure rules includes the use of factors have been adjusted for frequency/wavelength so the general OET-65/ ANSI/IEEE C95.1-1992 Maximum Permissible Exposure (MPE) values are weighted for the absorption of RF by the human torso, as well as the human head. This is one of the reasons why the standards chart is not linear and appears to have “tiers” as depicted below (from OET-65).
Aside from RF exposure factors, there are other health aspects to RF exposure that should be mentioned, specifically, RF exposure to implanted medical devices, such as defibrillators, pacemakers, and insulin pumps.
In general, subject to individual vendor specifications, these devices can tolerate up to 100 V/m, which is slightly more than the maximum general pubic level (above 30MHz) which equates to 61.4 V/m.
Below 30MHz, individuals with implanted medical devices must be careful to avoid contact currents with low-frequency emitters. In general, these sorts of antennas are reasonably large, and will not be utilizing high power levels for general consumer applications at these frequencies, though exceptions for very close exposure to some RFID readers with some implanted medical devices have been observed.
As with AC and DC measurements (although more so), accurate measurements and comparison to established Health and Safety regulations require sophisticated instruments and trained technical experience. It is possible to buy, on the open market, inexpensive instruments which measure AC/DC/RF/Microwave emissions – all in the same instrument.
FMS uses, exclusively, professional level instruments which are calibrated to Domestic and International standards and have considerable experience gathering and reporting measurement data in a wide range of Industrial, Commercial, Institutional and Laboratory settings.
Field Management Services, Inc. performed EMI surveys for the siting of an intra-operative MRI to be shared between two operating suites.
To mitigate EMI threat concerns, FMS designed and implemented multiple special magnetic field shielding schemes to lower EMF levels to acceptable, non EMI threat levels.
The Ivanpah Solar Electric Generating System is the largest concentrating solar thermal power plant in the world. At 377 megawatts nominal (392 MW gross)
Over its 20 years, FMS has successfully completed hundreds of EMI projects which included a diverse range of consulting and mitigation services.