The Environmental Protection Agency has decided to ignore risks it considers trivial in judging whether to ban pesticides because their residues may cause cancer, an agency official said Friday night.

Up to now, the agency has considered itself bound by the so-called Delaney Clause requiring it to ban chemicals which, when concentrated in food processing, can increase the chances of cancer, no matter how small the increase.Three years ago, the agency said it was trying to decide whether to consider the very small risk posed by some chemicals in food too small to worry about.

The EPA said then it believed a one-in-a-million chance of getting cancer from eating the food in question would be an acceptable standard of "negligible risk."

A report from a special committee of the National Academy of Sciences supported the agency's position. Environmentalists have criticized it on the grounds that it ignored the cumulative risk from eating many foods.

Linda Fisher, assistant EPA administrator for pesticides and toxic substances, said she had signed a decision Friday invoking the one-in-a-million "negligible risk" standard to permit two chemicals to stay on the market.

The state of California, the AFL-CIO and others had petitioned the EPA to remove seven pesticides from the market because of their cancer-causing potential.

One of the chemicals continued in use by Fisher's decision, benomyl, used on raisins and tomato products, increases the lifetime chance of cancer by less than one in 10 million, the agency believes. Another, trifluralin, used in peppermint and spearmint oil, raises the cancer risk by about one in a billion.

She said she was ordering one of the chemicals, dichlorvos, off the market, because, "We are not confident that it poses de minimis (trivial) risks."

Various restrictions may be ordered for the other chemicals and in some cases decisions are being delayed for more information, she said.

The Food and Drug Administration recently sought to adopt a similar policy for food additives but lost a court test.