Federal and state plans to spray 4,700 acres of Virginia forests with a powerful pesticide have met with angry opposition by residents of the rural area, who are threatening to go to court to block the spraying.

The spraying program, which has received the sanction of the federal Environmental Protection Agency, was requested by Virginia officials who feared that gypsy moths breeding in the wooded areas would damage nearby appel orchards.

But a group of families in Loudoun and Clarke counties and across the state line in West Virginia, contend that the government has not adequately studies the pestcide to determine what effect it might have on humans.

Residents of the Bluemont area have appealed to the Virginia Agricultural Review Board to stop a federally sponsored anti-gypsy moth spraying campaign planned to begin next week.

The group, which calls itself Concerned Citizens Against Dimilin, objects to the use of the pesticide Dimilin W-25 which has been approved by the EPA.

"At east 80 families live in these woods," said Peter Dunning. "Dimilin is unproven for human use. There are people who drive through that area to go to work; the Appalachian Trail runs right through it and I live there with my family. We've been given no information on how to protect ourselves," Dunning said.

Federal and state officials say that studies are still being conducted to determine long-term effects of the chemical on humans. But officials of both agencies said yesterday the chemical poses "no particular hazard" and plans will continue on the spraying program.

The U.S. Department of Agriculture will conduct the spraying in two two-week segments on three areas between Bluemont, Va. and the West Virginia border, where several concentrations of gypsy moth eggs have been spotted.

The program, which officials said would cost $80,000 to $95,000, is just part of a alrger, mid-Atlantic plan to eradicate the gypsy moth in West Virginia, Virginia, Pennsylvania and Maryland.

Gypsy moths eat the foliage of hardwood trees, including oak, maple, hickory and ash, and are especially fond of the leaves of apple trees. Apple orchards constitute a milti-million dollar industry in Virginia.

Last year Virginia officials trapped 74 male moths and three egg masses of 500 eggs each along the ridge schduled to be sprayed next Wednesday.

"In three years those moths could wipe out whole forests. We have to prevent that forested ridge from being defoliated, we have the rest of the state's hardwood forests to be concerned with," said Billy Southall, director of product and industry regulations, in the state agriculture department.

Neil Steinberg, a spokesman for the citizens group, said "we do concede the fact that the gypsy moth can be a problem. We're not sure we want to trade off the health of the people here."

Steinberg said the group has already made an appeal to the state's Agricultural Review Board which is expected to meet to discuss the issue Tuesday night. If this fails, Steinberg said, the group would seek a court injunction to stop the spraying.

Larry O'Neill, a spokeman for the EPA, said yesterday that "Dimilin is not supposed to be used in residential areas." But it is up to the state to determine whether an area to be sprayed is forested or residential.

Southall said, "Nobody will tell you what a sparsely populated area is. We chose Dimilin because it will insure complete eradication. Actually it is less toxic than other pesticides we've used in the past."

Because of restrictions on the use of Dimilin, Southall said the state plans to "pass out plastic to people to put over their springs and ponds. The EPA has advised us that there are no special precautions to take."

Southall said the state also plans to divert springs flowing from the forest areas into the Round Hill Reservoir for two days after each spraying in order to prevent any possible contamination to the Round Hill water supply.

Douglas D. Campt of the EPA's pesticide registration division said, "there are outstanding data gaps" in the agency's study of long-term effects of Dimilin on humans. Tests designed to determine if the chemical caused tumor growth in rats and mice or hormonal or blood have been "inconclusive" according to Campt.

Paul Edwards, a spokesman for Gov. John N. Dalton, said "the destruction the gypsy moth may wreck will be worse than any adverse effects on the people. We know there are a number of people seriously concerned, but it may come down to a court injunction to stop it." CAPTION: Map, Shading marks spraying area. By Richard Furno - The Washington Post