U.S. Civil Rights Commission Chairman Clarence M. Pendleton, Jr. yesterday denounced the concept of "comparable worth" as "probably the looniest idea since 'Looney Tunes' came on the screen."

The controversial concept holds that jobs dominated by women are underpaid because of sex discrimination and that wages for such jobs ought to be raised to equal those of men holding jobs of comparable skill and responsibility.

"I think you just cannot begin to do things to the marketplace that have served this country so well," Pendleton said at a news conference called to release 16 studies on the controversial idea, which labor, women's and civil rights groups have portrayed as a remedy for sexual discrimination in the nation's work places.

The commission, which makes recommendations to the president and Congress, has said it will not take an official position on the so-called "pay-equity" theory until early next year. But Pendleton and staff director Linda Chavez yesterday called it a serious threat to employers and to women who might lose their jobs if their employers were forced to raise their wages.

Commissioner Mary Frances Berry, a Howard University law professor, called it "inappropriate and outrageous for them to make statements on an issue the commission has not yet decided . . . and which has not yet had fact-finding." She said it was, to her knowledge, the first instance of a news conference being called without other commissioners being informed.

"This is a political preemptive strike" to support the Reagan administration's opposition to comparable worth "and deep-six the issue before it has a fair hearing," said Berry, a Democratic appointee.

Chavez said commissioners were not informed of the news conference partly because "it never occurred to us this would be a big deal." She said at the session: "I have attempted to ensure a fair airing of all of the issues surrounding comparable worth. However, I must in candor admit my own misgivings about a proposal that would so radically alter our existing marketplace economy."

Advocates of comparable worth maintain that the skills, experience and responsibilities of workers such as secretaries or nurses should be numerically compared to others, such as truck drivers or construction workers, to determine pay. "Equal pay for equal work" has long been a tenet of civil-rights law, but supporters of pay equity would extend the concept to "equal pay for comparable work."

Opponents of the idea -- including President Reagan, who regards it as "nebulous . . . at best," according to the White House -- argue that pay differentials between male- and female-dominated professions are a product of marketplace forces of supply and demand, rather than discrimination that government should attempt to remedy.

Numerical job-rating systems have been drafted in Washington state, under a court order now being appealed, and in Minnesota, where state officials have launched a four-year, $22 million effort to rectify sex-based pay disparities.

At least 20 states and scores of municipalities have introduced pay-equity bills to study and possibly change pay systems. In several cases legislation has been enacted, according to the National Commission on Pay Equity. "I think it is very sad they are referring to this as 'Looney Tunes' because there is a groundswell of activity by local and state legislators introducing bills to study and implement pay equity," said Claudia Wayne, director of the commission on pay equity.

The U.S. Chamber of Commerce has estimated that implementing a nationwide comparable-worth system would cost employers more than $300 billion, and Pendleton said he is concerned about "serious problems in the marketplace . . . that could cause the export of jobs" if employers were forced to raise wages. If wages of some office workers were raised, he said, "then coffee machines will replace them."

Berry said she found Pendleton's and Chavez's positions "amusing" because they give more weight to economics than to civil rights. "They define civil rights to suit their tastes and political interests."

Pendleton and Chavez said they held the news conference to release the 16 studies -- eight favoring and eight opposing -- and said they were speaking to express individual views, not the commission's. They said the failure to inform other commissioners was an oversight.

Of the 16 studies, Chavez said she attached most weight to the "human capital" theory outlined by Solomon Polachek, an economics professor at the State University of New York, Binghamton. This view is that women generally choose jobs that allow them to enter and leave the job market easily, primarily for child-bearing; while men end up in higher-paying jobs because they have invested more time in education and training, knowing that they would to remain in the workforce.

Pay equity supporters argue that "women's jobs" were historically assigned lower pay largely because employers did not regard women as bread-winners, a view invalidated by the growing number of single-parent households.

In another of the 16 studies, former Labor Secretary Ray Marshall argued that "deeply embedded" sex discrimination results in "job and pay assignments that reflect the belief that women are 'inferior' participants in the work force and therefore the higher status, higher-paying jobs are reserved for men."