An Arlington-based milk producers group, citing the possible effects of a toxic chemical spill near Culpeper, Va., yesterday renewed a ban on the sale of milk from a Culpeper dairy farm to Washington area consumers.

Kenneth Duckett, who runs the farm with his brother James, said the Maryland-Virginia Milk Producers Association took the action because of concern over the recent deaths of several calves there and because of elevated levels of copper reported in state tests on the milk.

Milk from the Culpeper area is normally shipped to Embassy Dairies, which serves much of the Washington area, according to the association.

Virginia dairy officials maintained yesterday that the ban is unnecessary. Although the copper level -- .25 parts per million -- is "not normally found in milk," a state regional inspector said, it is not regarded as unhealthy.

"People pay money for copper in vitamin pills," he said.

State tests on milk from Culpeper area dairies have failed to find any of the chromium or arsenic contained in the chemical spill, which was said to have occurred about Jan. 31 and swept through dairy pastures in local streams. No tests were conducted until Feb. 5, however, leaving authorities uncertain whether contaminated milk -- possibly hundreds of gallons -- was shipped to consumers in Washington.

The Ducketts were ordered on Feb. 6 to stop shipping milk because private tests showed traces of chromium and arsenic, a known carcinogen. They dumped about 700 gallons before the ban was lifted last Friday.

Embassy Dairy officials declined comment yesterday. Dairy association officials could not be reached.

State authorities have played down the significance of the spill, 200,000 gallons of toxic chemicals from a holding pond at Culpeper Wood Preservers, a lumber treatment operation, that turned a local stream foamy and green and left dead cattle, fish and poultry in its wake.

State water officials said they were unaware the pond existed until it was found during a routine stream survey last July. A toxic chemical dumping site once used by area manufacturers also is located nearby and drains into the same streams, officials said.

State veterinary officials in Warrenton refused yesterday to speculate on what might have killed dozens of calves in the area since last fall.