They are far from the jungles of the Southeast Asia of 15 years ago, yet Gene Dorr, Stephen Androff and John avalos are scantily clad in green camouflage fatigues, shorts and T-shirts. They fun the stagnant, humid Washington air in the crowded room atop St. Stephen and the Incarnation Church in Nothwest Washington where they and five other Vietnam veterans each plan to live on a gallon of water and the juice of one lemon a day until President Reagan agrees to meet with them and hear their demands.

Androff, 33, was an artillery forward observer in the Army in 1967 who went out in the brush and radioed the location of enemy targets to headquarters. He joined the fasting strike 30 days ago and says he will see it through to the end. "I got nothing to lose; I'm dying anyway on the installment plan."

Androff's face, arms and legs are splotched with red lesions that have been carving out holes in his skin for seven years. "At first I thought it was jungle rot [heat rash]," he said. Now he believes it is the result of exposure to the toxic herbicide Agent Orange, although Veterans Adminstration doctors disgree. "They give me pills and say it will go away but it doesn't. They say it's not Agent Orange, but they don't say what it is."

The fasters and the california-based Veterans' Coalition they represent want the federal government to finance on veterans of such herbicides as Agent Orange that were sprayed into the dense jungles of Vietnam.

The American Council on Science and Health, a nonprofit group of scientists specializing in public health issues, announced in April that their studies found that the herbicide did not cause grave illnesses in humans, but stopped short of making any conclusions about the claims of the Vietnam veterans.

Meanwhile, the Environmental Protection Agency has halted its efforts to ban 2,4,5-T, the controversial herbicide that is a component of Agent Orange, and has started negotiations over the domestic use of it. Several studies are under way on the effects of low does of 2,4,5,-T and Agent Orange on human beings.

The eight men are protesters who have brought their cause from across the country in a time-honored fashion of people who have a grievance -- come to Washington to lay your demands at the doorstep of government. The eight Vietnam veterans plan to camp -- two at a time -- in a tent at Lafayette Park across from the White House, while the rest of them stay at the church.

Most of the fasters claim to have some side effects from Agent Orange but Androff, a Los Angeles artist, is the most dramatic example. Because of Agent Orange, he says, he has not been able to father a child since he returned to the U.S. in 1969.

The eight veterans came to Washington last week, leaving four other fasters behind, including Michael Chapman, 29, who suffered a heart attack in Wadsworth, Calif. The strikers also want a nongovernmental investigation into the May 16 death of Janes R. Hopkins, a veteran who died from a drug overdose after becoming a cause celebre in California for his efforts to get the Veterans Administration to certify his hearing loss as service related.

Hopkins' death ignited a torch in the heart of the fasters that their supporters say they will carry until the federal government also approves a civilian readjustment program for Vietnam veterans to help those who suffer from alcholism, drug addiction and emotional problems. The sum of such problems among Vietnam veterans recently has been diagnosed as delayed stress or post-Vietnam syndrome.

"I want to be able to know that when I'm feeling suicidal or homicidal I can get help before I do something I don't want to do," Gene Dorr says calmly, as the long legs on his 6-foot-4 frame stretch over a lumpy red couch. "And I want to do the things delayed stress robbed me of."

Dorr, 34, says he has had 48 jobs and has been arrested 67 times -- mostly for drug and alcohol offenses -- since he was handed a general discharge from the Marine Corps 13 years ago. He was in the San Diego County jail on a drunk driving charge when the fasting started last month.

He joined the fast 27 days ago and though his weight is down from 203 to 184 pounds, his humor has not diminished. "Three weeks of fasting and you bring me Lite Beer?" he joked as he was handed his daily ration of bottled water. Others on the fast sipped cups of hot herbal tea that they admit they allow themselves twice daily if they wish.

Dorr enlisted in Torrence, Calif., in 1964 when he was 17 and became a sniper in military zones where "anythng that moved was killed. I lost a lot of friends out there. I lost a lot of me," Dorr says, referring to the memory lapses he started having while still in the service.

He calls them emotional blackouts, lapses that came 20 to 30 times a day, "sometimes for weeks at a time." It was during these times that he says he would wander from city to city, state to state, get drunk, get in fights and usually wind up in jail. Now Dorr's blackouts are minor and occur only once or twice a day, but the nightmares that take him back to the jungles of Vietnam remain.

John Alvalos, a 34-year-old former Marine machine gunner, recently reluctantly separated from his wife and two children because he could not afford to support them. They now live with her parents in Glendale, Calif., their hometown.

Alvalos, nicknamed Gunner, was hit by a mortar shell in the legs and back in 1967 during a raid and later was awarded a Purple Heart. He still has pain from the shelling and, combined with pain from arthritis in his spine, is unable to work. Alvalos has been unemployed since last year and his only income is a $59 weekly check from his state's Social Security office. Because of the arthritis, Alvalos says the Veterans Administration has judged his condition as nonduty related.

"I was a patriotic fool. I enlisted on the Marine Corps birthday. I was a Boy Scout, and a Woodcraft Ranger. Now I tell people I have disabilities and the government won't pay and they don't know what to think," Alvalos says, hunching his broad shoulders.

Alvalos, who is 5-foot-11, started the fasting weighing 220 pounds. His muscular chest, arms and legs seem unaffected so far by the loss of 20 pounds in 30 days.

The 5-foot-11 Androf is another matter. He has lost 14 pounds and now weighs 154. His ribs almost poke out of his back. His gray eyes float in a pool of pink that should be white.

"My mother called to tell me to take care of myself and to keep my chin up," he says laughing. "She says wear clean underwear. You never know when you'll have to go to the hospital."