Rep. Timothy E. Wirth (D-Colo.) has asked the Federal Trade Commission to investigate television commercials that encourage children to make toll calls to their favorite TV characters.

In a letter to the FTC, Wirth described the case of a Colorado constituent whose children had dialed toll numbers to "talk to the Muppets" after seeing an ad that told them how to do it. The commercials included a small printed statement that the call carried an extra charge, but Wirth said most young children "would be unlikely to comprehend" such a warning.

Such toll calls, sometimes called "scoop-lines," typically provide recorded messages, such as sports scores or weather information for a charge of between 50 cents and $2 per call.

"With most television commercials, parents have the opportunity to oversee their children's responses to the persuasive appeals through their control of product purchases," Wirth wrote. "With scoop-line services, however, even very young children have the capability of immediately 'purchasing' the advertised products simply by dialing the number appearing in the television commercial."

Wirth said the commercials promoting calls to the Muppets had been taken off the air, but asked the FTC to determine if such advertising violates any federal laws or regulations.

SPEAKING OUT ON SPAS . . . The FTC once again has extended the public comment period on health spas, this time at the request of the Association of Physical Fitness Centers.

A staff report, released in January, recommended that the FTC address problems in the health spa industry on a case-by-case basis rather than through an industrywide rule. The staff found that the industry's problems were restricted to particular companies, and said an industrywide rule was "likely to impose costs on consumers that would not be justified by the benefits."

The FTC has extended the deadline to June 7.

HEALTH COMPETITION . . . Virginia's ongoing review of health professional regulatory boards should keep trying to remove "restrictions that impede competition, increase costs and harm consumers without providing countervailing benefits," the FTC staff has concluded.

The state has been reviewing its laws governing the business practices of dentists, doctors, optometrists and veterinarians, and it requested the FTC staff's comments.

The staff cited certain restrictions that "may reduce competition and increase costs to consumers." These restrictions include laws limiting some advertising by health professionals, the formation of some professional associations, locating offices in commercial establishments and practicing under trade names.

Although the state has proposed some changes in its regulations for these professionals, the FTC staff said the proposals "continue to present potential problems."

MORE MILLER RUMORS . . . FTC Chairman James C. Miller III's plans have kept the rumor mills busy. Over the past few months, Miller has been mentioned as a possible Labor secretary, a possible chairman of the Council of Economic Advisers and a possible successor to David A. Stockman, director of the Office of Management and Budget. Now, the publication "FTC Watch" has Commerce Secretary Malcolm Baldrige replacing Stockman at OMB, and Miller filling the gap at Commerce.