An Evaluation of the U.S. Navy's Extremely Low Frequency Submarine Communications Ecological Monitoring Program (1997) / Chapter Skim
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2: EMF Measurement, Exposure Criteria, and Dosimetry
2: EMF Measurement, Exposure Criteria, and Dosimetry
Pages 21-31
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From page 21... ...
Exposure is a measure of the field strength of an electric or magnetic field immediately outside an organism over a specific period. Dose is a measure of the induced field strength within an organism over a specific period.
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From page 22... ...
. An electric field in the earn that is the sum of the fields induced by the magnetic field and the current flowing from the buried ground terminals.
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From page 23... ...
Fortunately, the most-important reported levels used in establishing treatment and control sites and in analyzing ecological data were well above these levels and are expected to be accurate representations of the magnetic fields. However, reported field levels like 0.0002 mG are not expected to be accurate.
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From page 24... ...
The output of this probe was a voltage proportional to the electric field. A probe to measure the electric field in the earth that consisted of two orthogonal electrode pairs.
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From page 25... ...
UTR] helped researchers to select study sites for the ecological monitoring program by determining whether they were in the treatment or control category.
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From page 26... ...
EXPOSURE DATA SUPPLIED TO RESEARCHERS UTR} made available to researchers data on magnetic fields and electric fields in the air, and electric fields in the earth. ITTR} provided extensive data on specific measurements of ELF EMFs at each site to the ecological monitoring teams.
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From page 28... ...
Dos~metry involves assessment of the magnitude and distribution of induced fields and currents within biologic organisms that are exposed to ELF EMFs. The induced fields and currents not only are functions of the externally imposed EMFs, but are determined by the EMF properties and geometry of the exposed organism and any nearby objects.
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From page 29... ...
In contrast, electric fields induced in hardwood stands by the same EMFs could be substantial. Calculations based on these simple models suggest that the field induced by a vertically oriented electric field in a 25-m tree could be as high as 5,000 mV/m and that induced by a horizontally oriented magnetic field as high as 29.8 mV/m.
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From page 30... ...
CONCLUSIONS REGARDING EMF MEASUREMENTS UTR! has done a good overall job of characterizing the ELF electric and magnetic fields in the vicinity of the treatment and control sites.
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From page 31... ...
When requested, these were provided. · The electric fields in the earth depend on local earth conductivity, so they require a more-thorough measurement survey to characterize them.
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