AS ''the feminization of poverty'' continues to find its way into today's headlines and editorial columns, a new study is giving the phrase a fuller, more graphic meaning.
Citing ''substantial underrepresentation in hiring,'' ''strong possibility of discrimination,'' and ''evidence of 'tracking,' '' a report just published by the Wellesley College Center for Research on Women comes down hard on hiring practices and not-so-subtle attitudes that exclude black women from certain jobs , from promotions, and from job training programs.
The figures that emerge from ''Uncertainty and Risk in Low-Income Black Working Women,'' a report prepared for the NAACP Legal Defense and Educational Fund, are startling:
* More than 1 1/2 million black women whose work provides the main support for their families are now below the United States Department of Labor's poverty definition of $9,000 for a family of four.
* Although they constitute the fastest-growing labor group in the economy, black women on average earn only 84 percent of what white women earn, and earn less than 50 percent of the income of white males.
* Over 43 percent of black women below poverty are involuntarily part-time workers who would prefer full-time jobs.
* Black working women receive substantially less in payments from public assistance and child support than their white counterparts.
* Only slightly more than one-quarter of poor black women workers are covered by pension plans.
* Only about one-third of black working women have health coverage available to them in the workplace.
''I think the big shock to us from this report was the fact that there are black women, the majority of whom are heading households, who are working but are making so little money that they're classified as poor,'' says Michelene Malson, director of the Minority Women's Program at the Wellesley Center. ''This should help people to understand that the feminization of poverty is not about women on welfare. It's about women who are working.''
One of the most persistent stereotypes to be exposed by the Wellesley report concerns welfare payments. According to the 1982 Bureau of Labor Statistics Current Population Survey, black women receive only 3.26 percent of their income from child-support payments, compared with 8.37 percent received by white women. Similarly, black women receive 10.5 percent of their income from public assistance, compared with 12.28 percent for white women.
''The myth has always been that poor black women were on welfare, but this clearly is not the case,'' says Bette Woody, principal investigator and project director for the study. ''The biggest surprise for me was the extent to which these women do not receive any other support for themselves or for their families. Although a lot of them are eligible for public assistance, they're not taking it. Their overwhelming support comes from their own salaries.''
In examining the reasons behind the markedly low incomes and lagging occupational status of black working women, the report looks at two contradictory trends. Although black women's skills and education have improved substantially over the past decade, they still tend to be concentrated in the most menial, lowest paying, and most unrewarding jobs in the general labor market.
''Contrary to some of the myths about the improvement of black women, as far as the workplace is concerned, there still is a pretty strong hiring bias across industry,'' Dr. Woody explains. ''In the private sector, where the bulk of the jobs are, those with the worst hiring records are banks, insurance companies, credit agencies, real-estate firms, and retail grocery and drug stores.''
By looking at such indisputable facts as wage structure, work scheduling, segmentation of jobs, workplace benefits, and job security and training, the Wellesley study marks a new path for research on black working women. Living conditions associated with poverty are seen to be the result of low wages, and not the effects of the pathological causes often cited in the past. As recently as a decade ago, for example, studies on black families either emphasized breakup and social disorganization or concentrated on teen-age mothers and those receiving public assistance. Then black families headed by women were thought to be ''inherently deviant.'' In this new study, black working women who are heads of households are characterized as ''fighters struggling for the survival of their families.''
In addition to its impact on black family research, the new study also is getting good marks from labor economists.
''Let's face it - most of the research on the labor market has been done about men, by men,'' says Julianne Malveaux, a specialist on women in the labor force and a professor of economics at San Francisco State University. ''Anything having to do with women has been very recent - say, in the past 10 years. So the Wellesley study represents a movement in the direction of looking more carefully at low-wage women.''
While Professor Malveaux hopes the NAACP Legal Defense and Educational Fund will undertake litigation as a result of the study, another labor economist thinks it should spark some broad policy debate.
Says Bruce Dunson, chairman of the economics and finance department of Prairie View State University in Texas and a consultant to the federal government, ''The study shows that we need some sort of policy that might be directed at the issue of women who increasingly are called upon to support families.''