WASHINGTON (AP) _ Hundreds of brands of insect repellents, including some types of OFF and Cutter's, are being withdrawn from stores because a long-used ingredient to repel biting flies gave tumors to lab rats and withered their ovaries.

The ingredient's manufacturer, McLaughlin Gormley King Co. of Minneapolis, gave the government test information disclosing the problem and asked that its license to produce and sell it be withdrawn, said Albert Heier, a spokesman for the Environmental Protection Agency.

''The company has voluntarily canceled their registration on this product and informed all the users,'' Heier said Thursday. ''They did the responsible thing.''

Some 200 brands hnson publicly announced its withdrawal of OFF earlier this month, but Cutter's said nothing in public, although it did notify retailers.

About 25 percent of all insect repellents on the market use the additive, known industrially as R-11 although that name does not appear on the label of any consumer product. The labels, instead, carry the long technical name, Heier said.

The manufacturer's test results showed that the additive caused ''adverse reproductive effects, ovarian atrophy and oncogenicity, or tumors,'' in laboratory rats and mice, the EPA spokesman said.

''These are the preliminary results; the studies aren't completed,'' he said.

The government has done no independent testing of the additive - it requires pesticide manufacturers to conduct safety tests - and does not know how dangerous it may be. The ingredient has been used for 35 years.

''We just don't have enough data to do a risk assessment,'' Heier said. ''We have no evidence that it hurt anybody.''

In the case of Deep Woods OFF, the withdrawal affects about 150,000 cases of aerosol and pump containers and boxes of towelettes, the company said in its public announcement nearly three weeks ago.

Cutter's, however, did not make a public announcement and instead quietly informed retailers to take products from their shelves, said spokeswoman Dionn Tron.

''Because there was no safety reason for doing this, it was simply a precautionary measure on our part, there was no public announcement,'' she said.

The voluntary recall involved several products carrying the Cutter's name, Ms. Tron said. Three Cutter's products did not contain the ingredient in question: the tick repellent, the maximum strength formula and the stick repellent.

The recalled products are being replaced with new ones carrying a yellow sticker saying it is a new formula, the spokeswoman said.

Sixty-five other companies also produce repellents using R-11 under a variety of brand names.

Among those are pet products, including some flea and tick repellents marketed under the Adams or Mycodex brand names, said Linda Kriesman, a spokeswoman for SmithKline Beecham Co.

The products have been reformulated, and those new formulas either have been approved already by the government or are awaiting approval, she said.

People with repellents containing R-11 who want to throw it away should handle its disposal as they would any pesticide in accordance with local ordinances, Heier said.

Ms. Tron said people with Cutter's products containing R-11 can contact the company, which will send a mailer to dispose of it.

However, she said there was no need to get rid of the repellent.

''People who have the stuff can continue to use it,'' she said. AP) - Those yellow and black federal labels that give the octane rating on gas pumps should be torn off because of cheating by gas stations and lax enforcement, the American Automobile Association says.

Reacting to a congressional report Thursday that estimates octane cheating could be costing motorists $150 million a year, AAA spokesman William Berman said car owners have only a 50-50 chance of getting the octane they pay for.

The report by the General Accounting Office found cheating by more than half of the service stations tested in Detroit and St. Louis last year, although it said only suspected cheaters were tested and that those results could not be projected nationwide.

''Car owners shouldn't have to take pot luck when they fill up their tank,'' Berman said. ''Those aging octane stickers out on the gas pumps are essentially meaningless and should be removed.''

A representative of service station operators accused Berman of exaggerating the problem and criticized the report as too sweeping an indictment of an industry that sells 113 billion gallons of gas a year.

''Service station operators have investments of $100,000 or more, and they're not going to jeopardize that,'' said Joseph Koach, executive director of the 60,000-member Service Station Dealers of America. But he acknowledged that there are some ''fly-by-night cheaters.''

''If the consumer wants to be protected, he can be protected by buying gas from qualified members of associations,'' Koach said.

A report by the General Accounting Office, the investigative arm of Congress, said that motorists who are buying higher-octane gas to get the ''ping'' out of their engines may be paying a premium price for gas that sometimes comes from the same storage tank as cheaper regular fuel.

Federal law requires that uniform labels on gas pumps show the octane rating of each type of gas - 87 for regular unleaded, 89 for leaded regular and mid-grade unleaded and 91 to 94 for premium grades.

The higher the octane, the more ability the gas has to get rid of ''ping'' or metallic ''knocking'' in the engine.

A low-octane gasoline can reduce engine efficiency, mileage and emissions in high-powered engines, the GAO said.

The GAO said the federal government has done little to stop the deception, although nearly half the states have testing programs that have curbed cheating.

Rep. Philip R. Sharp, D-Ind., who released the report with Rep. Charles Schumer, D-N.Y., said the study's estimate of $150 million in losses is conservative. He said the figure could reach as high as $600 million through growing mislabeling of octane ratings at the pump.

''Unfortunately, consumers cannot determine octane ratings visually or in other ways that allow them to know if they are getting what they are paying for,'' the report said.

It said problems were found in seven non-testing states visited by GAO investigators, mainly at the distribution and retail levels.

Frequent octane mislabeling was found in one-time tests conducted in Michigan, Missouri, Oregon and Tennessee, the GAO said, and investigators also found concern about octane cheating from officials interviewed in Indiana, Montana and Washington.

In 1989 Michigan tests conducted primarily in Detroit, 51.9 percent of stations had inflated ratings averaging 2.3 octane points, and in St. Louis 52.6 percent had mislabeled an average of 2.2 points, the report said.

In tests conducted in 1988, 21.8 percent of samples in Oregon and 22.2 percent in Tennessee were mislabeled, the GAO said.

States that now handle their own tests and enforcement are Alabama, Arkansas, California, Colorado, Delaware, Florida, Georgia, Illinois, Iowa, Louisiana, Maryland, Massachusetts, Missouri, New York, North Carolina, North Dakota, Oklahoma, South Carolina, South Dakota, Tennessee, Virginia and Wisconsin.