Corporate America must increasingly find ways to accommodate employees who need to take time off to take care of a sick or dying spouse or parent, experts say.

An estimated 48.9 million people, or 21.2 percent of the U.S. population, already provide care to an adult annually, according to a 2009 study by the National Alliance for Caregiving. But that number is expected to increase.

“You have an aging workforce, so therefore you are going to have more people with caregiving responsibilities,” said Steven Albert, a University of Pittsburgh professor.

Albert, co-author of a 2010 study on the cost of caregiving, estimates that it costs employers $17.1 billion to $33.6 billion annually.

The cost comes from employee absenteeism, a reduction from full-time to part-time work, the cost of replacing employees and workday interruptions.

Albert predicts the cost will increase in the future.

“It is a more socially mobile population, so kids do not live as close to their parents as before and people are staying in the workforce longer … so you have that additional extra risk,” Albert said.

Elaine Bannon, whose husband, Chuck Bannon, died of amyotrophic lateral sclerosis, or Lou Gehrig’s disease, took little time off of work.

However, she was able to employ a caregiver who took care of her husband during the day and had two close colleagues who were usually able to cover for her if she had to take some time off.

That’s an option few caregivers have, said Sue Burstein, executive director of ALS of Michigan.

Appropriate full-time care for a person with ALS can cost $1,000 per week, she said.

“It financially ruins families,” she said.

The Family Medical Leave Act allows employees who have an elderly parent or spouse with serious health problems to take up to 12 weeks off to care for that ailing family member and offers job protection.

But that time off is unpaid in all states other than California, said Deborah Russell, the director of workforce issues at AARP.

Despite the potential cost to employers, Russell predicts that America’s aging workforce will force corporations to adopt policies that accommodate caregivers to stay competitive.

“Flexibility in the workplace is the big issue,” she said. “Whether it is working a compressed workweek, or telecommuting in order to be home, that will become a huge selling point both for recruitment and retention of workers.”