The study by the National Center for Policy Analysis estimated $9.5 trillion is owed to current retirees -- an amount equal to almost $250,000 per person 65 years of age and older in 2008.

"The numbers are staggering," study co-author Andrew Rettenmaier, an NCPA senior fellow, said in a statement. "No one thinks we are going to end these programs, but if we account for federal obligations the way private pensions and state and local governments are required to, the federal government owes up to $52 trillion as of today."

Rettenmaier said that to put the numbers in perspective, the size of the entire U.S. economy is $14 trillion.

The study also said that:

-- Adding the liability owed to those nearing retirement, 55 and older, more than doubles the accrued debt to $20.6 trillion.

-- Adding the benefits accrued by younger workers brings the total to as much as $52 trillion. The beneficiaries include all retirees, as well as anyone in the workforce above 22 years of age.

-- By 2012, one out of every 10 income tax dollars will be needed to close the funding gap for Social Security and Medicare.

The study is online at http://www.ncpa.org/pub/st/st317/st317.pdf.