AMERICA'S retirement-security system faces challenges aside from the troubles at the federal pension-insurance agency:
* More and more companies offer pensions that are not guaranteed by the federal government and that give workers more responsibility over their own retirement dollars.
* Millions of working Americans have no private pension plan.
These shifts come partly as a result of structural changes in the economy, as employment shifts toward smaller companies and a less-unionized work force. These trends do not represent a crisis, analysts say, but they do signal a need for proper regulation and incentives for companies, and for education of workers.
Currently, only about 43 percent of the work force of 120 million is covered by a pension plan other than Social Security, says Dallas Salisbury, president of the Employment Benefit Research Institute, a nonprofit organization in Washington.
The picture is less grim than it seems, he notes, because many people work part-time. Among part- or full-time workers in the 45 to 64 age group, 58 percent have a pension plan.
In very small companies, 14 percent of the workers have no pension plan, versus 62 percent at firms with 1,000 or more employees.
Richard Freeman, an economist at Harvard University, characterizes the US pension system as "more unequal" than those of other industrial nations, but not necessarily a poorer system.
Many less-educated people who used to find blue-collar union jobs with pensions are now without coverage.
"It's today's problem and if it continues it'll be tomorrow's crisis," Professor Freeman says.
The danger, he says, is that the economy increasingly is increasingly bipolar: "We're made up of the Zoe Bairds and the ... maids," Freeman says, referring to the President Clinton's high-earning former nominee for Attorney General.
Mr. Salisbury, though acknowledging that the US system does not emphasize equality, says "the private pension system is stronger today than at any time in the nation's history."
Layered on top of Social Security are private pensions, which fall into two basic camps: Most large companies offer "defined-benefit" pensions, which provide for specific post-retirement benefits. This is the type insured by the federal Pension Benefit Guaranty Corporation.
"Defined-contribution" plans, by contrast, specify the employer's payments into a worker's retirement account during each year of work.
These plans, often known as 401 (k) accounts, have become increasingly popular, especially with smaller companies. This is because such plans are easy to administrate, easy to pass along to an employee leaving the company, and have a lower marginal tax rate, Salisbury says.
The retirement income from these plans is not necessarily lower, but vigilance and knowledge is required on the part of workers. Often they must make decisions about how retirement money is invested, such as the mix of stocks and bonds. Employers are increasingly offering seminars on such topics and Congress is moving to regulate the financial-adviser industry.
Many employers provide both a defined-benefit pension and optional 401 (k) plans.