The passage of the Food, Drug and Cosmetic Act of 1938--50 years ago this month--has been called one of the "most important events in modern American consumer protection." Not that the idea of purity of food and drink was anything new. As early as 1202, for example, King John of England proclaimed the first English food law, the Assize of bread, which prohibited adulteration of bread with such ingredients as ground peas or beans.Laws were also passed in Colonial America governing content of specific foods. Federal controls over the food and drug supply started in 1848. The first comprehensive Food and Drug act was passed in 1906, following the drastic revelations of the muckrackers and other reformers about conditions in packing and manufacturing plants.

But by the Great Depression, the law had been watered down by compromises, amendments and adverse court rulings.

Consider just a few examples:

- In 1931, six persons in California were poisoned by greens sprayed by a pesticide containing lead arsenate.

- In 1932, a 4-year-old Philadelphia girl died after eating fruit sprayed with toxic chemicals.

- A popular product promoted for weight loss in the 1930s was Marmola, a product containing enough desiccated thyroid to create serious health problems, but which couldn't be regulated as a medicine because obesity was not considered an illness.

- 18 cases of permanent blindness were recorded from use of an eyelash dye that corroded the user's eyeball.

- Radium water was heavily advertised as a cure for cancer.

- Although insulin has been used successfully for diabetes beginning in 1922, dozens of products continued to be advertised as cures for diabetes--without insulin or even a change of diet. Many of these patent medicines did not even have to list such harmful ingredients as arsenic or strychnin.

- And then in 1937, Elixir Sulfanilamide was linked to the deaths of more than 100 people--most of them children. The elixir was a liquid form of a new sulfa drug that had been tested for flavor, appearance and color, but not for safety. It turned out that the drug's solvent was diethylene glycol, the stuff used as antifreeze.

Stricter controls for foods and drugs has been debated for some time. But in the Depression economy, many people were afraid they would send the country farther into depression and would arrest medical progress. The Elixir tragedy ended the debate.

Whereas earlier legislation had given the government authority to prosecute manufacturers and sellers of unsafe products, it had to wait until products were sold and problems arose.

The new bill took what was for the time, a radically different approach. Food additives and drugs had to be proven safe before they could be sold. The emphasis was changed toward standards that would prevent problems. Instead of picking up filthy products after they were on the market, the FDA now inspected canneries, graineries and storerooms so that filth had less opportunity to contaminate a product.

Instead of acting on a drug after children died or were crippled, the FDA would now require testing before a product was sold.

Walk down the aisle of any supermarket or drugstore and you will see just how consumers benefit from the provision of the law.

Today's food labels tell the ingredients and whether there are artificial colors, flavors or preservatives. Where nutrients have been added, full nutrition labeling is provided.

Today's non-prescription products actually work. That's a simple change, but a radical departure from 50 years ago.

Today's cosmetics no longer contain scarring, blinding chemicals.

Today's medical devices, when appropriate, must bear directions for safe use, as well as warnings, when needed.

And perhaps even more important, today's patients and physicians are assured of drugs and medical devices that have been proved not only safe but effective: from antibiotics, cholesterol-lowering agents and emergency heart attack treatments to contact lenses, artificial knees and hip joints.

Fifty years ago, doctors and patients played a rouletted game--hoping that the medicine they chose from the many with miraculous claims was at least safe. And today, we are assured that preservatives, flavorings and colors can only be added to our foods after careful study, including tests, to rule out long-range adverse effects.

We have come a long way, and today we take many of these protections for granted.

But that doesn't mean that problems still won't arise. In fact, FDA Commissioner Frank E. Young told members of the American Council on Consumer Interests gathered in Chicago this spring that there has never been a greater need for consumer education.

"Largely because of the miracles of modern science, the public increasingly expects that 'magic bullets' will be found for almost any diesase or condition. These growing expectations have been accompanied by a skyrocketing desire for more information," says Young.

"The FDA has responded to consumer needs for more information because we believe an informed consumer is vital to avoiding potential hazards in FDA-regulated products and because education to prevent public health problems is often the best answer we have."

Areas where the public needs a clear understanding, he says, include how drugs are developed, reviewed and approved. AIDS is also an area requiring special measures. "We are doing everything possible to bring safe and effective drugs and vaccines to the people who need them as soon as possible."

But there is no doubt that AIDS patients and their families are being bombarded with an increase in fraudulent treatments that purport to do some good against the disease.

"With such a proliferation of new fraudulent products to treat AIDS, education is essential so that consumers can understand the difference between science-based medicine and magical cures, says Young.

And that is just one area where problems can arise.

We are, he points out, on the crest of a new wave of changes even more basic than those the FD&C act posed 50 years ago.

"Implantable medical devices like pacemakers and drug pumps, artificial hearts and other man-made organs, magnetic resonance imagers--devices few could have dreamed of in 1938--are just the first generation of increasingly sophisticated wonders before us.

"Perhaps of greatest significance, however, is the advent of genetic engineering which has already produced diverse wonders."

Like 1938, he says, 1988, is another watershed of challenge and opportunity. "Fortunately, the consensus formed in earlier years makes it possible to move forward with confidence, not goaded by disaster, but beckoned by the great promise of the future."

And that, indeed, may be the greatest legacy of the 1938 Food, Drug and Cosmetics Act.