Dr. Selma J. Mushkin Weissbrodt, 65, a former goverment economist who had taught at Georgetown University since 1970 and was an authority in the areas of health programs and public management, died of cancer Sunday in her Washington home.

Dr. Mushkin, who worked professionally under her maiden name, came to Washington in the 1930s. She was chief of financial studies with the Social Security Administration from 1937 to 1949, then worked as an economist with the Public Health Service until 1960.

She also had been a research professor at Johns Hopkins University during the 1950s and at George Washington University during the 1960s. She had been professor of economics and director of the Public Services Laboratory at Georgetown University since joining the school nine years ago.

Dr. Mushkin was the coauthor of a 1971 study of lead poisoning in Washington children. The study was carried out for the District of Columbia and among its major findings were that 30 percent to 50 percent of the city's children born to poor families may suffer from lead poisoning.

The report stated that the effects of the poisoning could range from mild nervous disorders to severe brain damage and death. The study was instrumental in showing how important was the control of lead-based paints and pointed out the importance of parental education and early diagnosis in combating the poisoning.

Dr. Mushkin also pioneered studies in health costs. Among her findings were that as much as 20 percent of the nation's health dollars were being spent to support the dying. The study contributed to the continuing debate on medical treatment for the terminally ill.

At the time of her death she was awaiting publication of a five-year study on the cost of illness in the 20th century. She was a consultant to a number of private and government organizations on the costs and benefits of new health programs and technologies.

She also had conducted studies on education programs in developing nations and on finance projects for state and local governments.

During the 1960s she was an adviser to the Commission of Intergovernmental Relations. She worked for the Urban Institute in the late 1960s and recently had been a fellow of the Woodrow Wilson International Center for Scholars at the Smithsonian Institution.

Dr. Mushkin had served as an economist with the Office of Management and Budget and with the Organization for Economic Cooperation and Development in Paris.

Her published work included "Economics of Higher Education," and "Academic and State Legislative Policies for Health."

She was executive secretary of the New Coalition of Mayors, Governors, and County Officials, and a fellow of The American Public Health Associaiton and the Institute of Medicine of the National Academy of Sciences. She also was a member of the International Institute of Public Finance.

Dr. Mushkin was a native of Centerville, N.J. She earned a bachelor's degree at Brooklyn College in 1934, a master's degree at Columbia University a year later, and a doctoral degree from the New School for Social Research in New York City in 1956.

Survivors include her husband, Israel S. Weissbrodt of Washington; a son, David of Minnesota; two daughters, Amy Monahan of Rappahannock County, Va., and Ellen Dagger of Charlottesville, and three grandchildren.