Servicemen who sprayed the defoliant Agent Orange from airplanes in Vietnam are not dying at a higher rate than soldiers who were not exposed to the herbicide, an Air Force study revealed yesterday.

In fact, they have a lower mortality rate than their counterparts in the general population, conductors of the study said, probably because they were in better health to begin with.

"We are not suggesting that exposure to Agent Orange doesn't have any adverse consequences," said Dr. George D. Lathrop, director of the study. "Maybe, its simply too early to tell."

But the preliminary findings prove that exposure to Agent Orange doesn't cause death within a short time period, he said. The average age of the servicemen being studied is 44 years old. They served tours in Vietnam between 1962 and 1971 when the military sprayed 12 million gallons of the herbicide in the jungle and on croplands.

The study, dubbed Project Ranch Hand after the code name for herbicide spraying missions in Vietnam, was released at yesterday's meeting of the Veterans Administration's Advisory Committee on Health-Related Effects of Herbicides, a panel of government scientists and representatives of veterans' organizations.

The findings were described as "extremely significant" because they show the soldiers being studied are within general "patterns of mortality." That is important, Lathrop said, because "if large numbers of the men suddenly begin dying because of cancer or heart disease or because of some other ailment, we will know that their deaths are not normal."

The Ranch Hand study is being closely watched by government scientists and veterans' groups because it is the only Agent Orange study whose methodology has been acceptable to the scientific community. The Veterans Administration's epidemiologic study, which is supposed to be the government's most complete Agent Orange study, has been delayed nearly four years, in part, because scientists claim the government cannot identify which soldiers were exposed to herbicides and how much exposure they received.

Veterans contend that the defoliant has caused numerous health problems, including cancers, liver and kidney troubles, nerve and skin disorders, fatigue, depresson, sexual dysfunction, deformed children, miscarriages and others. The VA counters that there is no scientific proof that Agent Orange caused those ailments.

Unlike the government's other studies, the Ranch Hand study has been able to identify soliders who were heavily exposed.

Last year, the Air Force proved that Ranch Hand crew members were exposed to higher amounts of Agent Orange than ground troops by reenacting several spraying flights with a substance similar to Agent Orange but not toxic. Because the C123 aircraft, which was used for spraying, only flew 150 feet off the ground, pilots generally kept the airplane's windows open to avoid flying glass during ground fire, they explained.

Scientists discovered that the open windows created a vacuum that sucked large amounts of the spray into the aircraft, often resulting in the crew being soaked.