The federal Centers for Disease Control in Atlanta either botched a $43 million study of health risks posed by the chemical defoliant Agent Orange or buckled under pressure from the Reagan White House to call off its research, the chairman of a congressional subcommittee charged yesterday. "Either it was a politically rigged operation, or it was a monumentally bungled operation," Rep. Ted Weiss (D-N.Y.), chairman of the Government Operations human resources and intergovernmental relations subcommitee, said at a hearing on the canceled Agent Orange study. "In the meantime, the American people, especially the Vietnam veterans, are left high and dry." The CDC halted the evaluation in 1987, asserting that a lack of military records made it impossible to determine which soldiers were exposed to the herbicide that was widely used to clear jungle undergrowth during the Vietnam war. Nearly 35,000 Vietnam veterans have claimed they suffered cancers and skin diseases and fathered children with birth defects as a result of exposure to Agent Orange, which contains the deadly chemical dioxin. However, scientists testifying before the subcommittee said military records do exist and show which Army companies were in areas sprayed by the herbicide, which was named for its orange-striped containers. Weiss submitted a letter in which a former CDC director stated that a White House Agent Orange task force had directed CDC to cancel its study on grounds that a "scientifically valid Agent Orange Exposure Study was not possible." Dr. Vernon N. Houk, director of the CDC's Agent Orange study as head of CDC's Center for Environmental Health and Injury, denied the charge and testified that the CDC was not politically pressured to cancel the study. He said the White House task force instructed the CDC to stop research only after CDC administrators made the recommendation to do so. During two hours of testimony, Houk said he preferred that Weiss believe the CDC bungled the study rather than that it was swayed by political pressure. "There was absolutely" no political influence, Houk said. "I'm sorry you think it was bungled. We think it was good science." Another scientist, former CDC statistician Dennis M. Smith, said CDC administrators changed the design of studies so often and switched variables so frequently that the results were meaningless. Researchers sometimes made up data to fill in gaps in the records, he said, so that "at one point people lost track of what was true and what was false." "We were doing bad science at the CDC," Smith said in an interview after testifying. "We knew we were doing bad science. . . a number of us were saying so." Smith, assigned to collect data on troop movements and location of sprays, said he used military records to develop elaborate maps showing where Agent Orange was used. Colored pushpins showed which military companies were in the direct line of distribution. Smith said the maps were hanging on his office walls when the CDC first contended that the study was hopeless because it was impossible to link soldiers to exposure. "That was just baloney. That was completely false," he said. The effort to evaluate the health risks of dioxin has a long history of science and politics at odds. "I think that science is being made into a whipping boy for the politicians," said Dr. Jeanne Stellman, a scientist who with her husband conducted an Agent Orange study commissioned by the American Legion. Stellman's study found that Agent Orange exposure can be linked to diseases in Vietnam veterans, results that were harshly criticized by Houk and others at a Monday hearing.