IN A LAND where marijuana is widely available and easily obtained, the federal government is prepared to supply so little of the legal commodity -- primarily from a three-acre plot in Mississippi -- that thousands of glaucoma and cancer patients are to be deprived of its use for medical purposes sanctioned by state laws.

And, using the "supply shortage" as a pretext, federal agencies are promoting a medically inferior chemical substitute called Delta 9 THC.

At the core of the problem is a regulatory Catch-22: Although 24 states since 1978 have legislatively recognized marijuana's medical utility, only federal bureaucracies can grow and distribute it legally. Furthermore, federal policy forbids marijuana's medical use, and the new state laws threaten to undermine Washington's entrenched drug abuse establishment.

Unable to block the passage of these laws acknowledging marijuana's medical value, unwilling to meet rising public demands for legal problems of medical access to it, federal agencies are using their control of the nation's legal marijuana supply to corrupt the intent of the state laws.

By design or gross mismanagement, the government has promised the states supplies of marijuana which do not exist; instead, federal agencies intend to force the states to accept TCH.

The idea of a synthetic "pot pill" like THC appeals to federal bureaucracies unwilling to admit that marijuana has medical value. As Dr. Stephgen Sallan of the Sydney Farber Cancer Institute notes, "Swallowing a gelatin capsule smacks far less of a 'pot party' than monitoring the smoking of a marijuana cigarette."

Yet there is no medical evidence which shows Delta 9 THC is as medically effective as marijuana. Indeed, just the inverse is true; available data indicate that synthetic THC is medicaly inferior.

Delta 9 THC is the chemical in marijuana which makes people high. THC was developed because it is marijuana's most powerfully psychoactive -- or mind-altering -- substance. Initially designed for drug research on animals, THC was never intended for prolonged human use, particularly in the context of a medical therapy.

One Eli Lilly pharmacist familiar with marijuana-like drugs recently dismissed THC's potential medical use, calling the synthetic "a very primitive substance." Even THC's most ardent bureaucratic advocates in FDA and the National Institute on Drug Abuse admit that the government's much touted substitute for marijuana is critically lawed.

Dr. Coy Waller, a University of Mississippi pharmacologist and sometimes government researcher, has warned FDA that "THC is an intractable substance that held up our research for years." The synthetic substance, Waller says, has the consistency of pine pitch.

Paul Davignon of the National Cancer Insititute reviewed THC's makeup in mid-1978 and declared the synthetic was "not acceptable" for medical use.

An internal National Cancer Institute memorandum, dated May 15, 1978, reports that a group of NCI researchers and cancer specialists found the government's oral THC to be "erratic" and "unreliable." The report concludes: "All in all, the [marijuana] cigarette may be the best means for administering the drug."

A recently completed National Cancer Institute study on the anti-nausea properties of oral THC provided an unexpected, and detailed, comparison between the synthetic and smoked marijuana.

Cancer patients involved in the studywere initially given THC, and for a short time it reduced nausea and vomiting. But investigators discovered that oral THC quickly lost its medical value when patients on the drug began to vomit despite "significant" increases in dosage.

In frustration the researchers finally permitted the cancer to smoke marijuana. Quoting from the study, "We switched patients to the inhalation route of administration [smoking] when vomiting occurred . . . In our patient populations, smoked THC [marijuana cigarettes] was more reliable than oral THC." THC is but one of many unique chemicals found in marijuana which has medical value and contributes to the plant's overall utility as a therapeutic agent. As Dr. Todd Mikuryia, a former director of federal marijuana research, notes, "We know that THC makes people feel high. But there is no reason to assume, as Washington has, that getting high on THC provides patients with the medical benefits they receive from smoking marijuana." Dr. Andrew Weil, an author-pharmachologist who specalizes in the medicinal properties of natural substances, agrees, even suggesting there may be a danger in moving away from the natural substance towards THC. According to Weil, "Anytime you destroy the complex chemical balance of a plant to create a single, synthetic substance, like THC, you run the risk of significantly increasing the possibility of negative, more serious, side effects."

Why is smoking marijuana better than oral THC? It's a question of what physicians call "bioavailability," a measure of how quickly and easily a drug enterts the human body.

When inhaled, marijuana eases nausea and vomiting in most cancer patients in about 10 minutes. THC, on the other hand must be swallowed, and the synthetic requires one to three hours for digestion. THC's absorption through the gastrointestinal tract is unpredictable, so dosage is difficult to control. Because of these problems, THC produces a different response in each person, and results are inconsistent from pill to pill.

In the January 1980 issue of the Journal of the American Medical Association, Dr. Gabriel Nahas, a noted cannabis researcher, estimates that "smoked marijuana results in a bioavailability 5 to 10 times greater than by ingestion of the drug."

Most cancer patients who smoke marijuana only require a few puffs before their nausea subsides. As soon as the nausea is under control they stop smoking, giving the patient considerable control over marijuana's much overrated "high." Patients taking THC, however, will require larger dosages to achieve a similar medical benefit, and this dose must be taken whole. Because THC is so highly psychoactive, the use of a larger dose beyond patient control significantly increases the possibility of an unpleasant, even frightening "high."

There is one additional, very distinct advantage to smoking marijuana. Cancer patients ask the obvious question: "If I'm vomiting my guts out, how am I supposed to keep a pill down for several hours?"

The effort to push THC is a belated attempt to disguise the fact that the government is running out of marijuana and cannot meet spiraling state demands. Between 1 and 3 million glaucoma and cancer patients live in the 24 states which have legalized marijuana's medical use, and even under the most restrictive programs, some 150,000 to 300,000 of these patients are eligible to use marijuana medically.

Federal officials, however, continue to assure states that existing supplies are adequate. Bob Willette, the official in charge of the government's marijuana stockpile, recently told the Georgia legislature his department could meet all supply requests. Yet in mid-1978 Willette told a federal committee that New Mexico's initial request for marijuana -- the first state request for government supplies -- threatened to stretch supplies to the limit.

Federal drug abuse agencies never have publicly discussed the government's "legal" supply in detail. But Freedom of Information Act materials show that the quality and amount of marijuana in the federal stockpile have declined dramatically since 1976.

In 1974, the potency of federal marijuana was 4 percent; that has declined now to 2.02 percent for the highest available dosage, of which there is only a small, already consigned amount. Remaining supplies, those available to the states, are of 1.3 percent potency or lower. Earlier this year, when Michigan requested supplies of no less than 2 percent potency, it was told that the highest potency might be as low as .88 percent.

The National Institute on Drug Abuse, moreover, has done nothing to increase cultivation efforts; the 1979 federal marijuana crop was a mere three acres.

Dr. Seymour Perry, chairman of an interagency committee investigating the supply situation, said as early as March 1979 that federal agencies could not possibly meet public demands, that NIDA had enough marijuana on hand for fewer than 250 individuals. Federal agencies, therefore, could meet the medical needs of about 10 persons in each of the 24 states unless a substitute for marijuana is used. The government would like THC to be that synthetic alternative.

At best, synthetic THC is only an alternative, not a replacement, and both substances should be available for medical use.