The American Federation of Teachers, joining the growing ranks of union congiomerates yesterday announced what it called a major new organizing drive aimed at an estimated 6 million workers in the rapidly expanding health care industry.

The campaign pits the 500,000-member teachers union in head-to-head competition with the American Nurses Association and several other unions actively recruiting members in the largely unorganized health field.

Reaction from the other groups was cool.

The ANA called it "another attempt by an AFLCIO affiliate to shore up their sagging membership," and a spokesman for the American Federation of State, County and Municipal Employes (AFSCME), which claims 300,000 health care members, said, "Based on their record in organizing teachers in the past, we don't think we have anything to worry about."

The AFT, whose rapid growth in the 1960s trailed off in the 1970s as teacher ranks stopped growing, is one of many unions that have sought new opportunities for growth as their home turf shrank.

This has led to growing diversification of unions, exemplified, an ALF-CIO official noted yesterday, by the organizing of surgeons at the Cook County General Hospital in Chicago by the Amalgamated Meatcutters.

At a news conference to announce the new drive, AFT President Albert Shanker said a newly created American Federation of Nurses division within the union will attempt to recruit 500,000 to 100,000 nurses and other health care workers within the next two years.

Shanker said the campaign will focus on an estimated 2.5 million health care professionals, including nurses, therapists and technicians, but not physicians. Nonprofessionals also may be organized if local units choose to do so, he said.

The ANA has organized about 200,000 nurses and has contracts covering half of them, while AFSCME and other ALF-CIO unions such as the Service Employes focus largely on nonprofessionals.

According to Shanker, the AFT is acting in response to appeals from nurses who wants an AFL-CIO union that serves primarily professional workers.

He said he expects the drive to begin by absorbing existing groups, such as nursing units that have left the ANA, but denied that the AFT will raid other union's ranks. As an AFL-CIO affiliate, the AFT is barred from such raiding, but may compete with other unions for unorganized workers.

"There's no reason for us to collide with each other," said Shanker.

Shanker said the AFT is prepared to spend millions if necessary on its health care organizing drive and plans a "substantial" expansion of its organizing staff including staff members from existing groups it absorbs.

He said expenditures of $1 million or more may be necessary in the first year. While dues increases may be required, they will not exceed those of other unions that are rising dues because of inflation, he said.

Shanker said the AFT, which is second in size among teachers unions to the 1.8 million-members National Education Association, has already branched out into other fields by organizing some state employes in New York, health care workers in Connecticut and state employed attorneys in Wisconsin.

Shanker acknowledged that the AFT, after expanding from 50,000 to 500,000 members since 1960, came to a standstill three years ago. But he said it is beginning to grow up again now, pointing to a recent bargaining election victory in Baltimore and gains in Louisiana.

The AFT's diversification will not be limited to the health care field, he said, noting that it may move into other fields as well as time goes on.