The Environmental Protection Agency yesterday was ordered to explain why it is allowing the use of existing stocks of two cancer-linked antitermite chemicals whose manufacturer has agreed to stop selling them.

Eight environmental and consumer groups, two unions and a woman whose house was contaminated with the chemicals had asked U.S. District Court Judge Louis Oberdorfer to halt use of the two antitermite agents, chlordane and heptachlor, which are classified by the government as probable carcinogens.

Oberdorfer did not grant the groups' request for a preliminary injunction, but ordered the government to produce all the documentation it used in deciding to allow a two-month supply of the chemicals to be used up -- even though it deemed them dangerous enough that sales should be halted.

The judge told lawyers for the groups to refile their request, and said the EPA would then have 10 days to respond.

On Aug. 11, the EPA announced that Velsicol Chemical Corp. of Rosemont, Ill., the maker of the antitermite chemicals, agreed to stop selling them while it tried to design application techniques to eliminate long-term human exposure. Under terms of the agreement, distributors and pest-control firms may use existing stocks.