Value chain · CLM-1342
Low confidence
The evidence behind this statement is thin, indirect or second-hand. Read it as a lead to check, not as a settled finding.
In plain terms
A US mouse study, with tests run in 1957 and published in 1961 or later, found that repeated short microwave doses too weak to warm the animals still made them put on a little extra weight. The authors argued that the safety limit of the day had been picked without a sound basis.
The claim as recorded
A paper by authors from Wright-Patterson Air Force Base and Indiana University reports that female mice exposed to 10 cm (2.45 GHz) microwaves at 0.02 W/cm2 for two minutes once every hour, day and night, for about three weeks, without measurable rise in internal body temperature, became 4 to 6 per cent heavier than controls. Three series of 100 exposed and 100 control mice gave similar results, and a sham comparison between the two cages differed by 1.02 +- 0.84 per cent. For acute 3 cm (9.37 GHz) exposures of 20 minutes or less, the paper concludes that heating related to the total energy delivered, about 0.22 watt-minutes/cm2 to reach 40 deg C internally, not to average or peak power or duration. It questions the basis of the 0.01 W/cm2 maximum permissible level, which it says was arbitrarily selected more than ten years earlier.
Evidence behind this: T3, printed conference proceedings, the register's level for proceedings (coord ruling 2026-10-03); the volume is not identified on the pages held, so peer review cannot be confirmed. Re-tier to T1 if the volume is found to be refereed.
Scope and limits
Outlet, editors and year are not printed on the pages held; the latest reference is 1961. The paper calls itself a by-product of experiments aimed at other questions and says there is "no rational basis" for comparing its series. Fig. 2-3-4 (PDF p.10 / printed 172) reads "8.6 watt-min/cm2 IN 432 DOSES (0.02 watt-min/cm2/IRRADIATION)", and 432 x 0.02 = 8.64 (our arithmetic). Dose figures are self-consistent at 0.02 watt-min/cm2 per exposure; 0.02 W/cm2 for 2 min would give 0.04, so the density or the 2-minute duration is misstated (our arithmetic). The duration is given three ways: about one month (p.174), 21 days (p.175), and 432 hourly doses, which is 18 days (our arithmetic). Weight is the only chronic endpoint, and no pathology is reported for the 10 cm series. The chronic density, 0.02 W/cm2, is twice the 0.01 W/cm2 level the paper discusses (our arithmetic). Mice; no scaling to people. SRC-724 (McAfee, Braus and Fleming 1973; CLM-1361) identifies this paper as a later publication, by two of that test's authors, of a 1957 Tulane growth test (PDF p.1), and states that 10 mW/cm2 for two minutes of each hour was actually used, not 0.02 W/cm2 (PDF p.5). This paper's own per-cycle figure supports that reading: 10 mW/cm2 for 2 min gives 0.02 watt-min/cm2 (our arithmetic), the value on PDF p.8 / printed 170, PDF p.12 / printed 174 and Fig. 2-3-4. On that reading the chronic density equals the 0.01 W/cm2 level rather than doubling it. The 1973 repeat, weighing mice one by one, found no growth difference, and its authors judge the 4 to 6 per cent within normal between-group differences (PDF p.4).
What it assumes
The 10 cm exposures count as non-thermal on the paper's test: no measurable rise in intraperitoneal temperature in preliminary runs.
Where it comes from
PDF p.1 / printed 163: "an average power density of 0.02 watts/cm2 was used exclusively" (10 cm, "2 450 megacycle"). PDF p.2 / printed 164: total energy to 40 deg C "relatively constant and approximately 0.22 watt-minutes/cm2" (normalised). PDF p.3 / printed 165: thermogenic properties "relate directly to the total energy continuously delivered", for "time periods of 20 minutes or less". PDF p.12 / printed 174: "two minutes, once every hour, twenty-four hours a day for about one month"; mean weight "4 to 6 per cent greater than the control group"; control cages "1.02 +- 0.84%" (normalised); "'maximum permissible dosage' level (0.01 watt/cm2)" (normalised); "arbitrarily selected more than ten years ago". PDF p.13 / printed 175: "After 21 days of chronic irradiation, body weight increased 4-6%" (normalised).
Basis: W/cm2 incident; watt-minutes/cm2 per exposure; per cent body-weight difference from controls
Related records
- Answers question
- QST-001 not published in this release
- Contradicts
- CLM-1361 The same lab that once reported microwaves made mice grow faster repeated the test properly and... (McAfee 1973 J. Microwave Power: a repeat at 10 mW/cm2 for 36 days found no growth difference and says the earlier growth report gave the density wrongly)
Cite this
energyaperture.com/c/clm-1342
CLM-1342, Energy Aperture, as of 1968 (per the citation in SRC-724 ref 3; not printed on the pages held).
Connected records
Other published records linked to this one. A list, not a judgement.
- Contradicted by
- CLM-1361The same lab that once reported microwaves made mice grow faster repeated the test properly and found no effect, and said its earlier...