Caution: the Blue Oyster Cult may have been dangerous to your health.

That was the latest drum roll coming out of the Food and Drug Administration, that bunch of spoil sports that already has scared us silly with warnings about hair dye, Laetrile and No Hunger Bread.

The trouble with the Blue Oyster Cult, ironically, has nothing to do with food and drugs. Or oysters. Or cults.

The Blue Oyster Cult, for the uninformed, is a rock band. It's very big on what's called the heavy metal circuit, complete with outlandish outfits, black leather trousers and Maltese Crosses.

The FDA thinks the Blue Oyster Cult should clean up its act - not the skin-tight jeans, but, specifically, the laser beams the band uses for light shows during concerts. And the apparently agrees, and says it is making changes that are acceptable to the FDA.

The light shows which are also popular in art shows and in discos are one of the rock world's adaptations of space age technology. They're all harmless enough, provided the beams are low-powered one.

At rock shows, lasers are beamed onto walls covered with mirrors or specially made vinyl screens. They explode into fantastic colors and make triangles and circles that dance, pop, dart and plunge through space like electronic Ping-Pong balls.

The FDA's Bureau of Radiological Health, which enforces laws dealing with radiation exposure, fears that careless use of the powerful lasers might cause burns or eye damage to concert goers.

No one has ever been injured by such lasors, according to FDA spokesmen. But with a host of big name groups - including "Led Zeplin," "Pink Floyd," "War," "Wings," "Yes" and "Earth, Wind and Fire" - using them, the agency doesn't want to taje any chances.

So Uncle Sam has started sending sleuths to rock concerts, seeking the answer to the same question that parents have been asking for a generation: Are rock groups danger-them, the agency doesn't want to take ous to your health?

The conclusion: Their laser light shows can be.

Lasers can produce dangerous light radiation, for performers and those they perform for, one FDA spokesman said. Some of the rock groups have laser lights which flash over the heads of the audiences.If someone held up a hand, for instance, and the beam of light bounce off a watch crystal or something it could bounce into someone's eye.

'It could damage the eye even before you had time to blink away from it, and the result would be a temporary blind spot in the eye. That's most likely the most serious thing that would happen."

The FDA notified rock groups and laser manufacturers of the potential dangers of light shows last November, informing them of minimum standards it had set.

Rock stars were understandably miffed. "It never occurred to most rock groups that they'd over have to worry about radiation, let alone the Food and Drug Administration," one FDA spokesman said.

The Blue Oyster Cult's problems began when the FDA paid a visit to one of its concerts in Dayton, Ohio, in late March. It was revisited a month later in Atlanta.

Then in May, the agency notified the band that it was in violation of a number of FDA standards. Many of the complaints were minor: Its laser equipment wasn't properly housed, or labeled, for instance.

But the FDA also came up with a major violation: The way the Blue Oyster Cult was running its light show made it possible for laser beams to come into contact with people in the audience.

It was told to either decrease the power of its laser system or design a new system to insure the beams would not come into contact with humans.

The band has agreed to correct the problem, FDA spokesmen said yesterday. "They'vetalked to people here and they've worked things out. Most of the groups get pretty cooperative when they find we might shut down one of their concerts."