One of the legacies of the Vietnam war has been another battle, the one over the herbicide Agent Orange, which was sprayed on vast stretches of Vietnamese greenery during the war and is suspected of damaging the health of those exposed to it.

Two surprising and maddeningly contradictory scientific results have emerged in recent weeks, adding to the mystery surrounding Agent Orange.

They come more than 20 years after the spraying began, and eight years after 250,000 veterans went to court seeking money for supposed health problems caused by the spraying.

Year after year, studies have given only disappointingly vague answers about whether dioxins cause severe health problems and whether the soldiers' exposure was enough to cause any of the effects veterans were concerned about, from birth defects to cancers. It has been a story of science and politics at odds, with science slow to reach any conclusion and politics pressing for action.

The new findings prompted 10 members of Congress to write outraged letters, veterans to reach for their pens and researchers to polish up their best equivocations in another round of what one expert called "a pitiful story" with no satisfactory resolution.

The first of the recent announcements was dramatic, and came from the federal Centers for Disease Control: A study of Vietnam veterans believed to have been highly exposed to Agent Orange showed no more dioxin -- the herbicide's key contaminant -- in their blood than in the blood of veterans who never set foot in Vietnam.

The CDC had been told by Congress to study the issue, but the Hill was not prepared for the results. The agency said that the low levels found in the veterans, well below federal health standards, left researchers unable to study what health effects, if any, may be related to dioxin exposure. In other words, the researchers could not find any significant exposure to work with, at least by the one method they tried.

Then came a report that appeared contrary to the CDC conclusion: A Veterans Administration study showed some Marines who were in Vietnam had an unexpectedly high rate of two cancers, non-Hodgkin's lymphoma and lung cancer.

The study, disclosed by The New York Times, made no connections between the cancers and Agent Orange. But non-Hodgkin's lymphoma is a cancer that had already been connected to dioxins in a study of Kansas farmers who used dioxin-containing herbicides.

For researchers, this raised a suspicion; for Vietnam veterans seeking compensation, it was proof.

"Now that conclusive proof is in," said Barry Kasinitz of the Vietnam Veterans of America, "it is time for Congress to act" and provide compensation to veterans.

"The work with the farmers and the VA study are not really comparable," cautioned Sheila Hoar of the National Cancer Institute and leader of the Kansas study. More work is needed, she said, to sort out the tangles -- different herbicides, different dioxins and different levels of exposure were involved in the veterans' and farmers' cases.

The congressional group, for its part, said $63 million had been expended by the CDC for a conclusion that was "unconscionable and irresponsible." The group, led by Reps. James J. Florio (D-N.J.) and Lane A. Evans (D-Ill.), also accused the VA of concealing the study, which the group said showed a link between Agent Orange and at least one kind of cancer. Florio and Evans asked for hearings into the matter.

The apparent contradiction of attitudes and of results comes from the difficulty of the problem. Because some troops sprayed the agent to clear foliage and others passed through the sprayed areas, the amount of dioxin exposure the soldiers received varied greatly.

To determine whether dioxin causes health problems, each study looked at herbicides with different dioxins and exposure in different kinds of conditions -- from factories to farms. The results varied widely as well, with one study showing that a cancer called soft-tissue sarcoma might be linked to dioxin, while another showed a possible link to skin cancer, and a third showed a possible link to lymphoma.

The studies seemed to contradict, rather than confirm, each other.

Furthermore, the level of cancers that might be produced by exposure appeared to be very low in any case. For example, if the results of the Kansas farmers' study were projected directly to Vietnam (which researchers say cannot really be done), then the total number of lymphomas that might have a connection to dioxin would be in the tens, or hundreds at most, among hundreds of thousands of exposed veterans.

Because of the confusion, the chief court case had an unusual resolution that did not help settle the basic issue of what Agent Orange may or may not have done to veterans, while at the same time providing compensation for some veterans.

U.S. District Court Judge Jack B. Weinstein of Brooklyn, who settled the case, said there is a "near impossibility of proving scientifically which adverse health effects are compensable and which are not." So, he approved a settlement in which the companies would give an amount that now totals about $215 million to veterans who may or may not have had significant exposure to the agent. Of the 250,000 claimants, about 25,000 totally disabled veterans and the families of about 10,000 who died will receive awards ranging from $12,000 to $25,000.

Lawyers for some veterans opposed the settlement, saying it was not enough and might end up giving Agent Orange compensation to the family of a veteran who actually died of "alcoholic cirrhosis."

Peter H. Shuck, Yale professor of law and author of "Agent Orange on Trial," said the new findings would probably have little or no effect on the legal situation because the court is nearly ready to dispense money, and other suits have been dismissed. The new findings, he said, do not offer any clear information one way or the other about Agent Orange effects.

The CDC studied a sample of about 10,000 veterans who apparently received high exposures of Agent Orange while in Vietnam. From this group, about a thousand were chosen for medical tests, chiefly to fix the amount of dioxin in the blood.

The results showed that the exposed veterans had a median level of 3.8 parts per trillion of dioxin in their blood. Veterans who never went to Vietnam had a median level of 3.9 parts per trillion. The study also showed no relationship between how heavily exposed the Vietnam veterans thought they were and the level of dioxin in the blood.

On the other hand, only current dioxin levels in blood were measured. It is not certain that these levels reflect either the amount of exposure, or the levels of dioxin where it counts -- in the body tissues where disease is caused.

The congressional group said CDC should find a new method of studying the problem.

The VA study was one that looked at all sorts of health and behavioral differences between 25,000 Vietnam veterans and 25,000 veterans who did not go to Vietnam.

Those who went to war showed many differences, including a higher rate of death by car accidents and drug overdose. For the group as a whole, there were no major differences in death rate for cancers or other illnesses.

A difference appeared, however, when researchers looked only at Marines. They had about twice as much non-Hodgkin's lymphoma as expected. Kasinitz of the veterans' group attributed the higher rate to the fact that the Marines often were in areas of heavy spraying. Some Army troops were also in Agent Orange areas, but their units were mixed with others, such as support troops, who did not go into sprayed areas.

About 35 Marines in the study died of lymphoma, compared with about 17 that would normally be expected for the group.

But the VA study results are confused by one design aspect. It was not designed to determine the cause of any of the health effects shown. Thus, going strictly by the numbers, the lymphomas could have occurred by chance or been caused by any number of other factors, including another herbicide.

For now, the CDC has been petitioned by the 10 members of Congress, who ask that CDC head James O. Mason find other methods to link dioxin and health problems and try them. The CDC has announced no decision.

Meanwhile, other studies continue, including a separate CDC study of rare cancers and dioxin.