There was no fanfare heralding the occasion, so you probably missed the news. The X-ray security machines at airports -- a walk-through annoyance for most passengers and a pass-through inconvenience for their carry-on luggage -- recently marked their 12th anniversary.

Since their introduction, the machines have had a definite impact in reducing the number of plane hijackings in the United States. In the first years of operation, the Federal Aviation Administration acknowledged that hundreds of discarded weapons were found adjacent to the machines in nearby trashbins.

As a psychological deterrent against air piracy, the X-rays now in operation at airports in this country and abroad should receive a vote of thanks from travelers. But they also have become the nemesis of hundreds of professional photographers and thousands of vacationers who like to take pictures.

The professional photographers claim that the machines are not safe, that the electromagnetic radiation -- used to scan the interiors of bags for guns and bombs -- fogs or otherwise damages their film. They further claim that the machines are capable of projecting an image of suitcase buckles or other hard objects onto undeveloped negatives.

Not long ago, I almost missed a flight from London when I refused to pass my camera gear under the X-ray machine and insisted on hand inspection. The security officer angrily insisted that the machine would not harm my film, but I was not prepared to believe him. He was, after all, a security officer, not a photo technician.

"We understand that the first priority is security," says Tom Dufficy, director of governmental affairs for the National Association of Photographic Manufacturers, one of several trade associations that have been studying the X-ray issue in the past few years. "But we are striving for a compatible arrangement with the airlines. We don't want people to be discouraged from bringing a camera on any trip."

Studies conducted independently by the FAA, Kodak and other manufacturers have all shown that one pass through a normal low-dose U.S. airport X-ray machine causes no visible change in photo images. However, after more than one pass, the findings vary dramatically between studies, and it becomes more difficult to ascertain the truth.

The FAA has stated that "although much speculation exists regarding the subject of possible X-ray damage to film, we are, to date, unaware of any specific instance of such damage that is substantiated by factual evidence."

To be sure, almost all U.S. airports have taken steps to minimize damage to film. Henry Kaska, Kodak's public information director, says, "People shouldn't be concerned about carrying unprocessed film through U.S. airports unless they're going to be going through more than five terminals."

Kaska says that in the past Kodak "has had hardly any film problems" with X-ray machines at U.S. airports. "We've had only one case in which film was damaged by American X-ray equipment." That was due to faulty equipment in Alaska a few years back, he says.

When it comes to overseas travel, Kodak takes a dramatically different position. A major study by the company concluded that undeveloped film will, in fact, be ruined by X-ray machines at many foreign airports.

"The X-ray machines in many foreign countries subject film to doses way in excess of the film's tolerance," Kaska says.

Kodak saw the first real volume of damage during the 1980 Olympic games in Moscow. "We've determined," he says, "that most X-ray machines in the U.S. emit low-dose units of one milliroentgen or less. Most film can handle up to five milliroentgens before any damage is noticed. Based on the film we saw coming out of Moscow, we determined that the Soviet machines emitted extremely high doses -- as much as 100 milliroentgens."

There are some airports where X-ray machines represent little more than a massive show of unnecessary force. A few years ago, passengers departing from Manila International Airport in the Philippines were subjected to no fewer than five searches: All checked baggage was opened prior to check-in; all hand-carried baggage was opened twice; there was a manual frisk-check for metallic objects; and, finally, carry-on baggage had to pass through an X-ray machine that looked as if it had escaped from the movie "The Day the Earth Stood Still." Hand inspection of film in Manila was an absolute necessity -- although it was not unheard of for security personnel to want to open cameras, whether film was inside or not.

Even if you and your film passed through visibly unscathed, you always seemed to leave Manila worrying about how the radiation you had just experienced might affect your health.

Lately, with the construction of new terminals in Manila, the Philippine government has made the security procedures somewhat less arduous, but the questionable X-ray machines there live on.

Other foreign airports where X-ray machines are decidedly unkind to film are London's Heathrow, Hong Kong's Kai Tak and Brussels' National.

Simple solutions would seem to be for passengers either to pack their film in their baggage to be checked or to ask for a visual inspection of cameras and film when they pass through security.

But a word of caution: Putting your film in your checked baggage will not always insure protection. In almost all foreign countries, checked baggage is subjected to even harsher X-rays than carry-on (this is especially true in Asia and the Near East). The other problem is that in many countries -- Italy, France, Spain and Japan, among others -- the security folks absolutely refuse to hand-inspect any carry-on item.

"We get letters all the time," says Kaska, "from people claiming that they were punished for asking for visual inspection. We had one lady in Brussels who was told that she either had to put her film through their X-ray machine or stay in Belgium. Given the choice, she left the country."

Irwin Diamond doesn't think passengers should be subjected to such abuse. Diamond is the president of Sima Products in Chicago, the folks who make "FilmShield" and "Super FilmShield" lead-laminated film pouches. "We wouldn't be in business if people thought these machines were safe."

In August 1976 Diamond filed a petition with the FAA, claiming that passengers were not being warned of film damage dangers at airports. The petition was denied by the FAA the following year. Diamond then initiated a suit in federal court in Chicago. It was denied. He filed a similar petition again in 1981, which was again denied in 1982.

The problem became even more significant when Kodak introduced its ISO 1000 high-speed film and Fuji introduced its ISO 1600. For the first time, the film companies put two warning notices -- on the inside of the film box as well as on the outside -- "request visual, not X-ray inspection of film."

Then the FAA warned airline passengers that the new high-speed color film could be damaged by the X-ray machines. The FAA in 1983 finally advised airports and carriers to put signs near machines warning passengers of the danger and encouraging them to request a hand search of their film and cameras. But Diamond says this is still not enough warning.

"The signs have about 28 lines of type listing warnings about things like firearms, and the film warning is part of the list," he says. "If the average person would stand and read the sign, they would never get through the line."

A recent survey of 500 travelers at airports in New York, Chicago, Miami and Los Angeles, taken by Technical Photography Magazine, found that 59 percent were not aware that warning signs were posted at X-ray checkpoints and 46 percent had no idea what the signs said.

To address issues important to air travelers who carry film, Darkroom Photography Magazine formed the X-ray Damage Awareness Committee last year. The committee consists of more than 20 members of the photographic industry, including Diamond. They have petitioned the FAA to increase public awareness by encouraging the X-ray checkpoint operators to alert travelers to the problem, by educating travelers about the problem before they are in the line so that they are prepared and by having a bold sign that can be read from a distance.

On the international level, the committee sent petition letters with 100,000 signatures to airport officials in those European nations that do not permit hand inspection of any carry-on luggage, requesting that they do so. Only Switzerland has said it will.

Some members of this committee are members of the American Society for Testing Materials. This standards committee, on which Dufficy of the NAPM also serves, has measured the damage levels of varying doses of radiation on various types of film. The problem of X-ray damage to film has definitely not yet been solved.

Some advice: Short of buying one of the FilmShield products (although at $9.95 for a regular, and $13.95 for a "super" model, it's a good investment), Kodak's Kaska recommends that you carry a clear plastic bag for your film so that security folks can easily see what it is. Don't carry a loaded camera, and always request a visual inspection of your film, no matter what assurances are printed on the X-ray machine.

Dufficy recommends also that you "have a jolly attitude with the personnel at the checkpoints. Don't be overbearing or demanding. Be polite and they should oblige you."