A White House-appointed advisory panel trying to map out how to evaluate the risks of thousands of pesticides has been unable to agree on much since it was created last spring.

The 52-member group was to complete its work this week. But the panel decided to meet at least twice more next year to tackle the complicated science of determining how much is too much pesticide residue in food, drinking water, lawns and households.

Members of the panel -- who include representatives of the pesticide industry, farmers, scientists, physicians and environmentalists -- are doubtful that key issues could be resolved without going to Congress and then, likely, the courts.

At the heart of the debate is how regulators should carry out a landmark 1996 federal law that ordered the EnvironmentalProtection Agency to evaluate all pesticides and apply an extra safety margin for children's health.

The EPA is required by the law to assess the first 3,000 chemicals by August 1999, then begin phasing out the most dangerous ones. The first batch up for review includes organophosphates, a class of pesticides widely used on apples, cotton, citrus and corn.

"It seems almost inevitable that at least some of this will come down to litigation," said Kert Davies, an analyst with the Environmental Working Group.

This week the group, which has a seat on the EPA panel, protested the slow pace of the agency's work and threatened to resign from the panel.

"We cannot in good conscience participate in a process that we feel is abetting a delay in protecting the health of our kids," Davies said.

Environmentalists say the EPA should move immediately to ban or phase out use of methyl parathion, a chemical used on one-third of the nation's apples and linked to damage in the brain and nervous system ofchildren.

But farmers are equally adamant that regulators cannot ban some of the most potent, inexpensive and widely used pesticides without further consideration of a number of factor.

"The land is my life and my future, and I will do everything I can to protect it and the health of people who eat my food," said Brad Luckey, a California citrus grower on the advisory panel. "We know the law is here, but we need a transition time to get through any changes and find cost-effective alternatives."

That means a go-slow approach to gather more scientific data about various chemicals. It also means trying to work out more "realistic" formulas to measure the impact of pesticides on children's health, and whether a 10-fold safety factor is justified, Luckey said.

Farm groups, which also say they are willing to go to court over the issues, have begun lobbying Congress to keep a close eye on how the EPA enforces the pesticide law.

Representative Ray LaHood, an Illinois Republican, is expected to get more than100 co-sponsors from both parties for a nonbinding resolution telling EPA to mind the instructions given to it when the panel was created by the White House. The resolution could lay the groundwork for any legislative push by agriculture groups next spring.

The EPA advisory panel is to meet again in February and April, after the agency solicits public comments how best to calculate pesticide residue in food and water.

Some of the organophosphate pesticides facing a possible ban include brands such as Lorsban, Cygon, Sevin and Dyfonate.