The Justice Department is investigating possible criminal violations by top officials of the Food and Drug Administration's Bureau of Drugs in connection with faulty testing of a purported "miracle" medicine called DMSO.

The FDA disclosed the probe yesterday at a Senate hearing after six DMSO users told poignant personal stories of how the drug, a byproduct of the paper pulp industry, had helped them and relieved their pain after all else had failed.

The investigation centers on sworn testimony by FDA medical officer Michael J. Hensley that bureau managers prohibited him from taking to federal officials evidence of grave flaws in the two studies on which the FDA based its approval of the drug for severely limited human use.

The bureau managers, who weren't identified, told him that DMSO was "politically sensitive," the physician told the Senate health and scientific research subcommittee. He added that DMSO's leading advocate, Dr. Stanley Jacob of the University of Oregon, had "political clout." Several legislators have said they use DMSO, or Dimethyl sulfoxide.

Subcommittee chairman Edward M. Kennedy (D-Mass.), presiding for three uninterrupted hours as if he had nothing else on his mind, asked FDA Commissioner Jere E. Goyan what he would say to Americans in light of the dissonant messages coming out of the hearing.

One message -- the agency's -- was that "possible malfeasance" in the bureau is under investigation by the U.S. attorney in Baltimore and that the safety and efficacy of DMSO -- in most medical conditions to which many physicians and patients would put it -- have yet to be demonstrated. It also noted that the drug causes often irreversible eye damage in five species of laboratory animals given doses proportional to those given humans.

The other message -- the witness-users' -- was what Kennedy termed the "extremely passionate" one about "what this drug did to relieve their pain and suffering."

In reply, a troubled Goyan said there are risks in the unapproved forms of DMSO currently being taken by hundreds of thousands of persons, including, he said, many who learned of the drug from an upbeat "60 Minutes" program segment telecast by CBS in March and repeated in early July.

One unapproved form is a technical grade of DMSO that isn't intended for use in humans. The others are experimental versions in which DMSO is combined with other chemicals to prevent users from reeking with an over-powering garlic odor, which the chemical normally generates. Applications to try out the experimental versions, for which the law requires FDA approval, haven't been filed with the agency. Preparations of DMSO for pets and other animals also are sold.

Goyan said he also was concerned because DMSO is a highly efficient "carrier" which, applied to the skin, can piggyback unwanted substances as well as useful medicines into and through the body.

Finally, the commissioner pleaded with the public to allow time -- estimated at two years or longer -- for "good studies" to be completed by Carter-Wallace Inc., a large pharmaceutical manufacturer, and Research Industries Corp. of Salt Lake City. RIC, in which DMSO advocate Jacob testified he has stock that cost him about $325,000 and is now worth about $600,000, had a key role in the flawed studies of the drug.

Most DMSO users get it for unapproved purposes, such as relief of pain from arthritis and sprains, reduction of swelling and treatment of assorted athletic injuries and neurological trauma. They rub it on their skin, drink-it or inject it into their veins. The only FDA-approved purpose is treatment of a particular bladder condition. Only "a tiny minority" use DMSO for that, Kennedy said.

Perhaps the most remarkable testimonial came from Jean Puccio, 49, a District of Columbia victim of scleroderma, usually an eventually fatal disease. It tightened her skin to the point that she had difficulty turning an ignition key and even eating and breathing. Now, after seven years on DMSO, "I can do anything anybody else can," she said. "I feel great."

Illy Roberts of Falls Church, who suffered a back injury that left her with severe, "unbearable" pain, said that after her condition was aggravated by osteopathy, acupuncture, exercise and other therapy, DMSO made her, too, feel "great."

Daryle Lamonica, while playing for the Oakland Raiders in 1967, applied DMSO to a thumb "so sore I couldn't grip a football," he said. The swelling "actually went down before my eyes."

Indiana University track coach Sam Bell told of several athletes who speedily overcame pain, swelling and serious sprains and other injuries with DMSO, which he and other witnesses obtained from Jacob.

Murray Becker, an 85-year-old New York City lawyer, said he suffered agonizing, even paralyzing pain in his calves for 30 years and got a "zero" result from repeated conventional diagnosis and treatment. DMSO, about which he learned from "60 Minutes," achieved "almost unbelievable" improvement, he told Kennedy.

The DMSO approved for use in the bladder disease is supplied by RIC. Testimony brought out that although the law requires a drug's sponsor to notify the agency of unexpected serious adverse reactions, RIC did not turn over a May 1977 report from a researcher on eye problems developing in DMSO patients.

The FDA's Hensley said that a random check on one of the two studies RIC had submitted to the FDA for approval of DMSO showed that eye and other safety tests on patients were either not done or were done improperly, and that the efficacy data "appeared to be little more than testimonials."

The physician who did the study, Dr. Sheridan Shirley of Birmingham, Ala., has consented to disqualify himself from further testing of experimental drugs.