Value chain · CLM-1347
In plain terms
In 1972 a leading American review said microwaves were only known to harm people by heating them. It called the evidence for other effects weak, so it argued against copying the far stricter Soviet limit.
The claim as recorded
A 1972 invited review in Proceedings of the IEEE judged that thermal effects of microwaves were well documented, but that evidence for a nonthermal effect was "at best only suggestive". It said Soviet reports of low-level effects on the central nervous system had not been confirmed outside the USSR, and criticised them for weak statistics, controls and quantification. It stated that all evidence then indicated an average power density of 100 mW/cm2 as the threshold for injury to the lens at 1 to 24 GHz. It said the only microwave effect determined to be hazardous was dielectric heating, and that the ANSI C95.1 guide of 10 mW/cm2 averaged over 0.1 h was roughly a factor of ten below thermal damage thresholds for exposures of a quarter hour or more. It reported no evidence in the Western literature of injury at 10 mW/cm2. It noted the Soviet limit of 0.01 mW/cm2 for a work day, or 1 mW/cm2 for 15-20 minutes, and recommended keeping the 10 mW/cm2 standard until better data and dosimetry existed.
Evidence behind this: T2, an invited, peer-reviewed review in Proceedings of the IEEE, written under an Atomic Energy Commission contract. It is the reviewer's assessment of the evidence, not new measurement.
Scope and limits
This is one reviewer's 1972 judgement, written while the standard was disputed. The page itself says groups were seeking both lower and higher limits. The 100 mW/cm2 lens threshold is a summary of animal and accident evidence, and the review also reports rabbit cataracts at about 110 mW/cm2 for repeated 1 h near-field exposures (printed 411). It does not cover effects later studied at lower levels. ANSI C95.1 was revised in 1982 (held as SRC-659) and the public limit later fell to the ICNIRP 2020 value (CLM-0008). The Soviet figures agree with CLM-1297 and are context only. This record states the 1972 Western position on nonthermal effects, not current evidence.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
PDF p.21 / printed 407: evidence for a nonthermal effect "is at best only suggestive". PDF p.22 / printed 408: low-level CNS effects "have not been confirmed outside of the USSR"; criticised for limited statistical analysis, inadequate controls and lack of quantification (paraphrase). PDF p.26 / printed 412: 100 mW/cm2 average power density at 1000-24000 MHz "is the threshold for pathophysiologic effect on the lens of the eye". PDF p.27 / printed 413: "The only effect of microwave radiation which has been determined to be hazardous is the dielectric heating"; the 10 mW/cm2 standard "is roughly a factor of ten below thresholds of damage by thermal effects" for exposures of 1/4 h or more (paraphrase of the condition); Soviet 0.01 mW/cm2 for a work day, 1 mW/cm2 for 15-20 min; "the best solution at present is to keep the 10-mW/cm2 standard".
Basis: mW/cm2 average power density; 0.1 h averaging; 1 to 24 GHz for the lens threshold
Related records
- Answers question
- QST-001 not published in this release
Cite this
energyaperture.com/c/clm-1347
CLM-1347, Energy Aperture, as of 1972-04.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-705
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