TWENTY-FIVE years ago, Congress decided to ban dyes added to foods, drugs and cosmetics if tests show the dyes can cause cancer in humans or animals. After all these years, however, several suspicious colorants remain in wide use, and the Food and Drug Administration seems to have concluded that Congress didn't mean what it said back in 1960.

When Congress added the "Delaney clause" to the law governing foods, drugs and cosmetic safety, it justified this strict ban on the grounds that dyes, while pleasing to the eye, provide no medicinal or nutritional benefit. The bleed-proof maraschino cherry that only Red Dye No. 3 can produce may have aesthetic value for some connoisseurs of chilled Manhattans or canned-fruit cocktails. But is it worth even the smallest risk of cancer? In 1960, anyway, Congress decided no.

But the FDA, under industry pressure, has managed to drag out its evaluation of color additives to the point where 10 coal-tar-based dyes remain in wide use despite the fact that they have flunked one or more cancer tests. By the end of last year, it looked like the game was up for at least six of them.

Three successive FDA commissioners, including the incumbent, had recommended banning one or more in the group. FDA expert panels, in the last two years, unanimously proposed banning all six. A top agency official warned that calling for still more reviews would simply damage further FDA's credibility and expose it to lawsuits. Subsequently, however, the current FDA commissioner, Frank Young, apparently changed his mind about the ban, and Health and Human Services Secretary Margaret Heckler announced that she is leaving all six dyes -- along with four other suspects -- on the market, perhaps indefinitely.

Some FDA officials and consumer groups have charged that the Office of Management and Budget and the Department of Health and Human Services -- succumbing to industry pressures -- have forced FDA to act against its best scientific judgment. The full membership of the House Government Operations Committee, including 12 Republicans, charged last month that Secretary Heckler is violating the law.

She argues that Congress didn't mean to ban colorants that caused cancer in animals if the tests showed that, in normal usage, they posed only a very small risk to humans. She says that the statute ought to be applied to allow her department discretion to decide if mothers really should worry about the brightly colored foods that so attract their children or the cumulative effects of a life- time of chewing off their own lipstick. But if Congress thinks that, it ought to rewrite the law. At the very least, it should require that items containing these dyes be clearly labeled so that consumers can make town choices about risk.