Two major coal groups have asked Interstate Commerce Commissioner Heather Gradison to disqualify herself from an ICC ruling that eliminates regulation of rates railroads charge when they haul coal destined for export.

The petition, from the National Coal Association and the Coal Exporters Association of the United States, Inc., says Gradison should disqualify herself because she worked for the Southern Railway Company for eight years prior to her appointment to the ICC and the Southern was a major proponent of deregulating export coal rates.

The Southern has merged with the Norfolk and Western to become the Norfolk Southern. About 40 percent of Norfolk Southern's revenues come from hauling coal.

Gradison's vote was critical in the ICC's 3-to-2 decision on March 3 eliminating regulation of export coal rail rates. The decision will become effective 90 days after the formal decision document is released, which has yet to happen. All that is known now about the decision is contained in a three-paragraph press release which lists only the names of the dissenting voters (Chairman Reese H. Taylor Jr. and Commissioner J.J. Simmons) and not those of the three who voted for deregulation (Commissioners Gradison, Malcolm M. B. Sterrett and Frederic N. Andre). All commissioners are Reagan appointees.

If Gradison were to disqualify herself and the other votes did not change, the issue would remain undecided as it has for more than two years.

In their petition, the coal interests quote the ICC's Canon of Conduct, which states that members of the ICC "shall not participate in any matter . . . in which their impartiality might reasonably be questioned."

Gradison had no comment because, she said through a spokesman, "the petition is a matter before her for a decision; she needs to review the matter and issue a decision."