Value chain · CLM-1327
In plain terms
In 1972 the experimental evidence put the onset of microwave cataracts at about 10 times the then US limit, for acute exposures, and found the 1-3 GHz band the most effective. Nobody had tested years of low-level exposure.
The claim as recorded
A 1972 peer-reviewed review of the microwave cataract literature concludes that most experimental evidence indicates a threshold of about 100 mW/cm2, possibly as low as 80 mW/cm2 for repeated exposures, and that these are time-power thresholds: the higher the power density, the shorter the exposure needed. Examples it reports at 2450 MHz are 0.59 W/cm2 for 5 minutes to 0.29 W/cm2 for 90 minutes in rabbits, extrapolating towards about 120 mW/cm2. Repeated exposures, none cataract-forming alone, could add up if spaced too closely for repair. The most effective frequencies were 1000-3000 MHz; below 1000 MHz opacities could not be produced below lethal levels, and around 10,000 MHz higher power was needed. Pulsed and continuous waves of the same average power appeared equivalent. No absolute threshold could be set because there were no data on very long continuous exposures at low power density. On non-thermal effects, the review judges the evidence to suggest a purely thermal mechanism but not conclusively. An addendum reports that a 1970 federal report found no cataracts in rabbits exposed in free field below 110 mW/cm2, nor after 25 one-hour exposures at 100 mW/cm2.
Evidence behind this: T2, a peer-reviewed journal review; it permits "the review concludes Y" on experimental cataract thresholds, not that any level is safe.
Scope and limits
Most data are near-field exposures aimed at the eye, often in rabbits, whose heat regulation the review calls poorer than man's; the review says dosimetry differed between laboratories so power levels are hard to compare. Waveguide-coupled results do not apply to free-space exposure. These are acute and subacute thresholds; the review says long-term low-level exposure was untested. Not a statement about 5.8 GHz, which lies between the frequencies it discusses.
What it assumes
Mostly rabbit eyes exposed in the near field close to a 2450 MHz diathermy source.
Where it comes from
PDF p.4 / printed 70 (render): "Most experimental evidence would appear to indicate a threshold of about 100 mW/cm2 and possibly as low as 80 mW/cm2 for repeated exposures"; "there is no data available on very long term continuous exposures at low power densities". PDF p.2 / printed 68: thresholds "of 5 minutes at 0.59 Watt/cm2 to 90 minutes at 0.29 Watt/cm2". PDF p.5 / printed 71: "The evidence at present tends to suggest that the effect is strictly thermal but this cannot be taken as conclusive." PDF p.7 / printed 73: "With frequencies below 1000 MHz it has not been possible to produce opacities with power levels below the lethal level." PDF p.8 / printed 74 (render): "no cataracts could be induced in rabbits exposed to free field microwave irradiation at power densities of less than 110 mW/cm2".
Basis: mW/cm2 incident, with exposure time; MHz
Related records
- Answers question
- QST-001 not published in this release
Cite this
energyaperture.com/c/clm-1327
CLM-1327, Energy Aperture, as of 1972-01.
Connected records
Other published records linked to this one. A list, not a judgement.