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SUBJECT Meeting with A. on the Moscow Microwave Exposure Hazard Problem, 3 April 1965.

1. Attached is a memorandum prepared by Dr.A Alon the Mos ow Embassy microwave exposure hazard problem. Graphs of radiation density for each of the. wavelengths of ,interest and other data which formed the basis for this memorandum are also attached.

2. To paraphraseAconclusios and recommenáations, personnel exposed to microwave radiations as described would not be harmed. However, the assumed maximum energy densities are less than an order of magnitude away from known harmful power levels. Therefore it is essential that the actual energy density be measured and plotted at building surface and inside and that continuous monitoring be done to detect any increase in energy which may be applied from time to time.

3. Once actual power levels are known, which we need to know from the point of view of past exposures as well as from the point of view of continued exposure, then a decision can be made as to whether or not the Soviets should be asked to shut the generaiors off..

4. In tris connection it is important to take note of Soviet regulations concerning maximum permissible exposure to microwave radiations in the 2 KMC, 5 KMC and 9 KMC frequency -regions, 3.3 cm, 6 cm' and 15 cm respectively, to which our people are being exposed. The .official Soviet maximum permissible exposure, during a full working day, to microwaves in the l to i2 cm band, as approved by the Chief State Sanitary Inspector of the USSR, Dr. V. Zhdanov, in Sanitary Regulation No. 273-58, published 26 November 1958, is 10 microwatts/cm2. This is one thousand times less than the accepted American standard of l0 milliwatts/cm2. Assuming a maximum exposure of our personnel of 21 milliwatts/cm², this would be 2l00 times the maximum permissible exposure level acceptable to the Soviets themselves. Even though we consider the Soviet standard to be completely unrealistic, it

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SUBJECT: Meeting with Alon the Moscow Microwave Exposure Hazard Problem, 3 April 1965.

is real to them and should be quoted to them in any diplomatic note of protest concerning this exposure of our people. While measurements of the actual power levels are being made, a 'search for any amendments or changes which may have been made in Sanitary Regulation 273-58 can be completed.

CONCUR:

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C00022059"

n

Memorandum to Dr.

Project Monitor

The lens of the eye is the most sensitive indicator of microwave injury and this discussion will be limited to a treatment of this organ response. Thus, the lens will serve here as our indicator of radiation exposure hazards. When injured by microwave radiation, the lens forms a cataract.

In accordance with current state-of-the-art knowledge and clinical credibility relating to the parameters of personnel hazard associated with exposure to microwave radiation fields, my best estimate of threshhold for cataractogenesis is at a power level of 100 $m w / \sin ^ { 2 }$ 。 This appears to be in the nature of an all-or-none reaction, and does not appear to be exposure time dependent. Cataracts resulting from microwave exposure usually are not clinically evident until after a latent period of months to years.

The personnel exposure problem presented in this case assumes the following parameters:

1. Three microwave generating sources with following characteristics:

2 KMC producing 0. 1 $m w / c m ^ { 2 }$ incident to the point of interest.
5 KMC 11 0.5 $m w / c m ^ { 2 }$ 11 11 11 I1 t1
9KMC 1 1.5 $m w / c m ^ { 2 }$ 11 Is 11

2. All three gererators could be emitting simultaneously and therefore the total energy density could be 2.1 mw $1 0 m ^ { 2 }$

3. Personnel inhabit a building at the point of interest.

4. It was assumed by the monitors that the energy densities quoted above could be greater by one order of magnitude; namely, a combined total energy density of $2 1 m w / c m ^ { 2 }$

Under the above conditions, it is my opinion that personnel may

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n

Memorandum to Dr.

口

Project Monitor

be permitted to inhabit the building under existing circumstances. 2 However, in view of the currently accepted standard of 10 mw/cm"as the maximum permissible level of continual exposure to r-f fields, it is undesirable to permit this condition to continue indefinitely without more precise knowledge of the exact parameters of exposure.

In this connection, at the present time, U.S. Army, Navy and Air Force as well as the American Standards Association are advocating that the maximum permissible exposure levels be increased above would advocate the following safe time limits of exposure:

Army/Air Force

Navy

ASA

12 minutes per each hour
48 minutes per each hour
30 minutes per each hour

The validity of these safe exposure times has not as yet been established but represent best estimates of these groups.

Therefore, I recommend the following:

1. Detailed study to determine the precise nature of the microwave fields including continuous versus pulsed emissions, repetition frequency of pulsed operations, peak and average power densities, standing wave plots, multipath summations including topographical reflections from intervening buildings and ground and return from internal corner reflectors (which may have been incorporated originally or later installed) and requisite continuous monitoring.

2. Selection of suitable copper screening and mandatory coverage of all window openings.

3. Periodic slit-lamp examination of all exposed personnel, specifically looking for thickening and/or opacification of the lens capsul. The

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Memorandum to Dr. D Project Monitor frequency of examination, where practicable, should be at one to two year intervals up to a maximum of 15 years following last known exposure date. There is no need to follow personnel exposed to less than 1 mw/cm².

4. A survey be made of all microwave emitting equipment (diathermy, ovens, etc.) in the building to insure adequate screening in order to minimize additional background burden.

April 3,1965

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