Today is the running of the Belmont Stakes, the third jewel in horse racing's triple crown. Everyone who has picked up a paper in the past five weeks knows how Kentucky Derby winner Genuine Risk will attempt to regain her honor by defeating California upstart Codex, the horse that allegedly defeated her in the Preakness. Even if the filly does not win, her future at a posh breeding farm is ensured. But for thousands of other thoroughbreds in the United States, the future will not be so good.

Take Easy Edith. Easy Edith was a 5-year-old mare with arthritic knees and a chronic soreness in the legs. What she really needed before her next race was a few weeks in a pasture. But expenses for a racing thoroughbred are high, and every day Easy Edith was not running was money out of her owner's pocket. So on May 3, 1978, Easy Edith walked onto the track at Pimlico, her knees treated with corticosteroids and her system full of phenylbutazone (Bute), an analgesic administered before the race to numb the pain. Her pain deadened, Easy Edith ran hard on her damaged legs -- too hard. Somewhere around the final turn, her left fore cannon bone shattered, and Easy Edith went down, causing three other horses to fall with her. Two jockeys were injured in the fall, and a third, Robert Pineda, was killed. Easy Edith was destroyed by the state veterinarian on the track.

Although no one knows to what extent the Bute or steroids were responsible for Easy Edith's breakdown, an out-of-court settlement was reached last week in a civil suit filed by Pineda's heirs against Easy edith's trainer and owner, three veterinarians and the Maryland Jockey Club. It was reported that Pineda's heirs were awarded a six-figure settlement after alleging that the jockey's death was directly attributable to the drugs administered to Easy Edith.

For every one Genuine Risk there are thousands of Easy Ediths -- cheap claimers past their prime whose winnings barely earn their own keep. The abuse of medicine to keep those horses running has become so widespread that the "sport of kings" is rapidly being redubbed by some "the sport of drugs."

Over the past few years, many states have adopted liberal drugging policies, allowing horses to run that otherwise would not. In addition to the "legal" drugs Bute and Lasix -- a diuretic not yet proven effective as a remedy for so-called bleeders -- some trainers have also taken to using such narcotics as Demerol, methadone and morphine and then masking them with allowable substances.

Even in the states where Bute and Lasix are banned, track enforcement is often lackadaisical. It has been estimated that several thousand drugs can be used to manipulate a race horse's performance, yet track chemists routinely screen for fewer than 100 compounds. Some are so elusive that chemists don't even know how to screen for them. Only in 1978 was a test developed to detect Sublimaze, a pain-killing narcotic classified as a Schedule II controlled substance in the United States.

Drugs permit unfit horses to race; the result is often to aggravate existing injuries and shorten horses' careers. Often medications administered have toxic side effects, or make the horses temporarily or permanently sterile. In states where figures have been kept, breakdowns like Easy Edith's have increased more than 100 percent since permissive medication policies went into effect. As the number of breakdowns increases, so does the number of injuries to riders. The Jockey's Guild estimated that in 1978, approximately 2,000 jockeys fell down with their mounts. Four died, four were paralyzed and 1,500 were hospitalized for longer than two weeks.

Public outcry has recently prompted some states to take action against excessive drug use, but many reforms have been little more than cosmetic. One problem is that state racing commissions fear that if they tighten drug policies too much, horsemen will take their animals to states where drugging regulations are more lenient. Two weeks ago, when the Maryland Racing Commission decided to put a complete ban on Bute and restrict Lasix use to confirmed bleeders, the president of the Horsemen's Benevolent Protective Association predicted that the action would prompt many owners to move their horses to Delaware, where the drugs are legal.

For a state to find itself losing horses to another state is more than just a matter of pride. It's big money. Horse racing is the largest spectator sport in America. In 1975, nearly 80 million people attended horse races, and more than $7.8 billion was bet at the nation's tracks. In 1979, California alone took in $113.3 million in racing receipts.

The only way to bring about a uniform, effective and well-enforced ban is through federal legislation. Such legislation has already been introduced in the House and Senate and is awaiting the scheduling of hearings. "The Corrupt Horse Racing Practices Act" would prohibit the racing of drugged horses, provide for both pre-race and post-race testing and establish civil and criminal penalties for violations. The bill would set minimum standards for drugs and allow those states already in compliance with the federal guidelines to administer the program themselves.

The states by themselves cannot curb the current flood of drugging abuses. Horse racing is clearly an interstate industry and its regulation requires federal assistance. The United States is the only major racing country that does not have a nationwide law on the drugging of race horses. For the sake of the horses, jockeys and bettors, it is time for that to change.