Three committee chairmen yesterday asked the House ethics committee to investigate discrepancies between the original transcript and the published record of hearings last July on the Environmental Protection Agency.

In a letter to Rep. Louis Stokes (D-Ohio), chairman of the Standards of Official Conduct Committee, Reps. Jack Brooks (D-Tex.), Don Fuqua (D-Fla.) and John D. Dingell (D-Mich.) requested a "vigorous, full and complete investigation."

The transcript of the joint hearing by five subcommittees of the Government Operations, Science and Technology, and Energy and Commerce panels was altered, in the words of Rep. Larry Winn Jr. (R-Kan.), to make Republicans look "silly, frivolous and uninterested." The statements of some Democratic members and witnesses also were altered.

Five Republican members of the subcommittees yesterday held a press conference at which they objected to having the ethics panel handle the investigation.

"This is so egregious, so outrageous, that there ought to be an open and public hearing," said Rep. F. James Sensenbrenner Jr. (R-Wis.). " . . . Sending it over to the ethics committee means that everything will be held in secret."

Republicans on the subcommittees and Democratic staff members said that the transcript likely was altered by a Democratic staff member. The transcript was prepared for publication by the Government Operations subcommittee on the environment, energy and natural resources.