Answer to Question #12166 Submitted to "Ask the Experts"

Category: Micro/Radio Waves, Radar & Powerlines — Microwaves and Radiofrequency

The following question was answered by an expert in the appropriate field:

Q

I am trying to locate information on the long-term effects of overexposure to radiofrequency (RF)/microwave radiation from SPS-10 surface radar. In 1981 I was aboard a U.S. Navy ship when I was exposed to RF radiation from an SPS-10 surface radar. The exposure was due to another person not properly securing the radar (as they signed that they had on the lockout form) before I went to work on the antenna. As a result, I was exposed within a distance of less than 1 meter (m) with the antenna radiating directly at me for between 15 and 20 minutes. The beam would have been hitting the top of my head. Per the manufacturer's equipment manual, the stay time within about 5 m is 0 seconds.

I was exposed at the age of 22 and am currently 58, almost 59. Over the years I have developed extreme psychological issues and have been diagnosed with bipolar disorder. I have had extreme depression and anxiety episodes that have progressively gotten worse and have been very bad in recent years. I am trying to find evidence to present to the U.S. Veterans Administration (VA) for a claim I have submitted regarding this incident and my current deteriorating condition. I am already being seen by the VA (I have no other health insurance), but no one at the VA will provide a statement that my condition may have been caused or drastically worsened by this exposure.

When I search the internet, the information I find mainly talks about current RF communication devices or a link between radar exposure and cancer. I can find nothing that discusses my issue in terms I can understand. Any help you can provide would be appreciated.

A

First off, thank you for your question and for your service. I, too, served in the military (Vietnam era and later), and I was exposed to various sources of shipboard energy, including the SPS-10.

I am sorry to hear about your health battles. However, the symptoms you describe do not coincide with established effects of overexposures to RF fields, which would result in heating-related complications.

The SPS-10 radar was the main medium-range, surface-search radar for the U.S. Navy for decades. It was manufactured by Raytheon and operated in the frequency band of 5.450–5.825 gigahertz (GHz; 1 GHz is 1 billion cycles per second). The antenna of this C-band radar was about 3.2 m by 1.9 m, and rotated at 15 revolutions each minute. Even though the power was 190–280 kilowatts (kW), the relatively short pulse width of 0.25–1.3 microseconds (μs or 1 × 10-6 seconds) and the narrow beam width (1.5°) would result in lower potential RF exposures.

The biological effects from RF fields are threshold in nature, which means that unless a threshold of exposure is reached, no biological effect will be observed. And any effects observed during the RF exposure are absent with removal of the RF exposure. This is especially true in the microwave frequency bands, which are conventionally above 1 GHz.

The World Health Organization (WHO) had this to say about the potential exposures from military radar in fact sheet No. 226:

Human exposure to EMF [electromagnetic fields] emitted by radar systems is limited by international standards and protective measures, which were adopted on the basis [of] the currently available scientific evidence. In summary:

  • RF fields cause molecules in tissue to vibrate and generate heat. Heating effects could be expected if time is spent directly in front of some radar antennas, but are not possible at the environmental levels of RF fields emanating from radar systems.
  • To produce any adverse health effect, RF exposure above a threshold level must occur. The known threshold level is the exposure needed to increase tissue temperature by at least 1 °C. The very low RF environmental field levels from radar systems cannot cause any significant temperature rise.
  • To date, researchers have not found evidence that multiple exposures to RF fields below threshold levels cause any adverse health effects. No accumulation of damage occurs to tissues from repeated low level RF exposure.
  • At present, there is no substantive evidence that adverse health effects, including cancer, can occur in people exposed to RF levels at or below the limits set by international standards. However, more research is needed to fill certain gaps in knowledge.

For more information, see the full WHO report.

Donald L. Haes, Jr., CHP, CLSO

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