One-third of Americans are "shelter poor," spending so much of their incomes on housing that they cannot afford other necessities, a new study reports.

The study by the Economic Policy Institute, a liberal economic research organization, said 27 million households "are unable to meet their non-shelter needs at even a minimum level of adequacy" because of high housing costs.

Those households contain 78 million people, or 32 percent of the population, the organization said.

The study said 42 percent of all who rent their homes were "shelter poor" in 1987, the last year of the study. Twenty-two percent of homeowners were in that category, it said.

The number of "shelter poor" households rose from 18.7 million in 1970 to 26.5 million in 1987, a 42 percent increase, the study found.

The study's author, Michael E. Stone, professor of community planning at the University of Massachusetts in Boston, used an index that assumes a family pays its rent or mortgage first, then uses what income is left to pay for basic needs such as food, clothing, transportation and medical care.

He concluded that people are "shelter poor" if their household has too little left after paying the housing costs to afford the minimum basic necessities.