POTATO INSECTICIDE SALESA North Carolina company said last week it would temporarily stop selling the insecticide aldicarb for use on U.S. potatoes after field tests unearthed samples with higher-than-expected residues of the product.

Rhone-Poulenc Ag Co. of Research Triangle Park, N.C., which produces all aldicarb used on U.S. potatoes, said it was carrying out the voluntary withdrawal in conjunction with the U.S. Environmental Protection Agency.

"Although proper use of the product for nearly 17 years has not resulted in any adverse health effects, some recent data have shown an unexplained isolated incidence of residue levels higher than acceptable in a few potatoes," said Stephen Schmotzer, Rhone's director of environmental affairs.

The company, a unit of the French chemicals giant Rhone-Poulenc SA, decided to withdraw aldicarb because it could not determine the reason for the high residues.

Aldicarb, which is acutely toxic and can affect the human nervous system, is used to control insects on about 15 percent of the U.S. potato crop.