In 1975 at Arlington Memorial Hospital, nurses wheeled a patient from the intensive care unit to a private room, which faced an FM radio station. An electronic thermometer used to measure the patient's temperature registered 108 degrees, a life-threatening level. But when the patient's temperature was taken with a glass thermometer, it was normal. Later, Environmental Protection Agency engineers found that radio frequencies in the room measured about three to four times higher than an average room. "Probably not enough to cause biological effects," explains Richard Tell, chief of the EPA's nonionizing radiation branch. "But enough to interfere with the electronic thermometer" and enough to make a wrong diagnosis.

All across the nation, the radio and television signals that broadcast classical music, the latest hit tunes and the nightly news are also the chief source of electric and magnetic fields that expose Americans to a kind of radiation considered of questionable safety -- and in some cases potentially dangerous -- by growing numbers of scientists, engineers and consumer groups.

A new EPA study, set for release this week at the National Association of Broadcasters (NAB) annual meeting in Las Vegas, pinpoints 231 potential "hot spots" generated by FM radio stations alone. These sites are considered "hot spots" because they produce a type of radiation known as nonionizing radiation at levels higher than that considered safe by the American National Standards Institute (ANSI).

Nonionizing radiation includes the low-energy waves that are used for communication, national defense and manufacturing. It allows microwave ovens to cook and carries messages from cellular phones. It raises garage doors and makes video display terminals work.

Broadcast stations are the predominant sources of nonionizing radiation exposure, with 90 percent of broadcast exposure coming from FM radio stations, says EPA's Tell.

FM radio signals and VHF television signals, in particular, have the unusual ability to couple with the human body "in such a way that the body acts as an antenna," explains Dr. Ross Adey, associate director for research and development at the Veterans Administration Hospital in Loma Linda, Calif. The longer and thinner you are, the better an antenna you are.

"If FM stations are not isolated from the community," Adey says, "people may be wandering in and out of fields of sizable levels and about which very little is known about the health effects."

This prompted the EPA to survey stations to pinpoint those that produce levels of nonionizing radiation that could be dangerous to people living and working nearby.

Exposure to nonioizing radiation goes largely unnoticed, primarily because it is invisible, has no odor and cannot be felt, unless it reaches such high levels that it heats tissues, the way a microwave oven cooks food. Yet there may be significant long-term health effects, which researchers are just beginning to determine. Among these are brain damage, a higher risk of cancer and increased chance of birth defects.

The current controversy over the potential dangers of nonionizing radiation focuses on just what levels may be harmful -- an issue that produces heated debate among industry groups, radiation safety organizations and federal agencies. No enforceable federal guidelines or regulations exist in the United States today for dictating exposure levels at either the workplace or among the general population.

Typical of other types of exposure that have occurred as a result of nonionizing radiation produced by broadcast stations are these:

* Atop the Villa at Eaton Square, a skyscraper condominium complex in Honolulu, portable radios blare music on the roof even when they're turned off. Rooftop sun worshipers are bathed in radio waves at levels higher than that recommended by the International Radiation Protection Association. This occurs because the signals generated by a nearby AM station are strong enough to turn the building into a giant antenna -- a transformation so effective that when EPA engineers recently strung a metal cable from the top of the building to the bottom to make measurements, the captured radio signals running down the cable were powerful enough to melt a penny on the ground nearby.

When the EPA investigated this site and 21 others in Honolulu, the results showed that "public exposures in 12 out of the 21 survey locations exceed limits currently proposed, recommended and/or adopted by several scientific and technical advisory or regulatory bodies," reported Joseph Gannon, EPA Assistant Administrator for Air and Radiation.

* In San Jose, Calif., the back yard of an expensive house built high in the hills overlooking San Francisco Bay sits in the shadow of a tall FM radio tower. When the owners go outdoors, they walk through a radio field that blankets them -- and anything else in their yard -- with doses of nonionizing radiation eight times higher than the level recommended by the American National Standards Institute.

The "hot spot" list, says Tell of EPA, indicates how widespread exposure is in the United States to nonionizing radiation based on "the best possible data available today." The FM stations found on the list are located in "Any City, USA," not just major cities, he says. They include cities from Seattle to New Rochelle, N.Y., and from Las Vegas to Ypsilanti, Mich.

The broadcast industry questions whether any adverse health effects exist as a result of exposure to nonionizing radiation. "For more than 50 years, broadcasters have provided communications services to the nation, with absolutely no evidence of harm to the listening and viewing public," NAB President Edward O. Fritts said in an announcement released in January.

"We are not living in a riskless society," adds Jules Cohen, an engineering consultant to NAB. "We have to accept some modicum of risk."

The NAB readily acknowledges the contribution radio and television signals make to the production of nonionizing radiation and calls ANSI "America's most experienced standards-setting organization. Its radio energy standard was developed after exhaustive study and provides scientifically based guidance to ensure that there is no risk to the public from radio wave energy."

Based on the results of the EPA survey, 88 percent of the FM stations that exceed ANSI standards have "inadequate fences to prohibit public access," Tell reports. About a quarter of the stations have "inadequate property boundaries," so that even if they were to fence in the radio towers, they still would not be able to keep the public a safe distance from the radio frequencies that exceed ANSI standards. "But there are other measures which they could use, which include selecting a different antenna," Tell says. "We found that virtually all the stations could be fixed."

Nonionizing radiation is measured by the number of watts for a given area, usually across a square centimeter, which is roughly the size of a dime. No one knows exactly how much exposure to nonionizing radiation the average American receives. But based on EPA studies, about one in every 100 Americans is exposed to levels of nonionizing radiation that exceed one microwatt per square centimeter, until recently the Soviet standard. The Soviet Union and other Eastern Bloc countries set some of the most stringent exposure limits, although many researchers question how strictly those limits are enforced.

In the Washington metropolitan area, some three in every 100 people -- about 70,500 Washingtonians -- are exposed to one microwatt or more per square centimeter, usually by living or passing within the shadow of a broadcast antenna. Estimates are that people who live within about a block of FM stations probably receive some of the highest exposure.

In this country, several private organizations suggest standards, none of which are mandatory, but most of which are used as guidelines for the military, the broadcast industry and others in establishing limits of what might be safe.

The least rigid of these standards comes from ANSI, which promotes 1,000 microwatts per square centimeter as a safe standard for nonionizing radiation -- significantly higher than the 17 microwatts per square centimeter used in the Soviet Union. Other suggested standards set by the International Radiation Protection Asociation and by the National Council on Radiation Protection and Measurements, an organization chartered by Congress, favor setting stricter limits on nonionizing radiation exposure. For FM radio stations, these limits run around 200 microwatts per square centimeter -- still higher than the Soviet standards but far less than that recommended by ANSI.

In another report also set for release this month, the EPA detailed changes the broadcast industry would have to make to comply with various standards. The Lawrence Livermore National Laboratory, part of the Department of Energy, calculated the cost of compliance for the broadcast industry.

The EPA estimates that it would cost the broadcast industry about $12 million to meet the ANSI standards. Imposing the more stringent 200 microwatts per square centimeter -- the level recommended by the other two standards organizations -- would cost the industry about $23 million. At 100 microwatts per square centimeter -- guidelines the EPA attempted to propose last year -- the price to the industry would be $34 million.

For each FM station, these costs average about $3,200 to meet the ANSI standard (1,000 microwatts), $3,700 to meet the 200 microwatt level, and $3,800 to comply with 100 microwatts per square centimeter. FM stations create more exposure because of antenna configurations, amount of power and height of the antenna towers.

"EPA has given attention to this important issue," says Don Justesen, president of the Bioelectromagnetics Society, a professional organization of researchers. "I just think that when the average person looks at the ordinary broadcast tower, it doesn't seem to bother them."

In the meantime, on Oct. 1 new FCC rules go into effect that govern the type of antenna new stations can use. By 1986, those rules will also affect existing broadcast stations, which will then be required to use antennas that meet ANSI standards in order to be relicensed.

"If we can't regulate and we've been trying to do that for a long time, at least let's tell people where they are exposed to the highest levels [of nonionizing radiation]," Tell says, "and let's let them make their own choices."