A cancer lurks within Floridaís otherwise rosy job numbers, one thatís been called a quiet catastrophe and an intractable time bomb.Too many men between the ages of 25 and 54 have stopped working.Economists call those the prime-age years. Incomes generally rise, houses get bought, retirement plans grow. The ride can be bumpy, but fired and laid-off workers typically get back up and look for new jobs.A huge swath of prime-age men, however, have dropped out entirely. They arenít looking for work and donít count against the unemployment rate. In economic lingo, they arenít "participating" in the workforce.In Florida, the number has grown from 9 percent of prime-age men in 2003 to 11.3 percent last year, according to the Current Population Survey from the Census Bureau. That might not sound like a big jump, but it translates to 135,000 more men (for a total of 430,000) who spent last year on the stateís economic sidelines.Put another way: The dropouts outnumbered unemployed men who were still looking for work by 4-to-1. In fact, the dropouts have outnumbered their unemployed brethren every year going back to at least 2003, even during the depths of the Great Recession.Jobs werenít exactly scarce last year, either. The stateís unemployment rate fell from an already low 4.6 percent in January to 3.9 percent in December.More Business: Why are lumber prices so high? Nationally, more than 7 million prime-age men have exited the workforce. Nicholas Eberstadt, a demographer with the American Enterprise Institute, has said the "seeming flight from work" results in slower economic growth, lower living standards, greater income inequality, higher social-welfare bills and larger budget deficits."It is imperative for the health of the nation to bring back these outcasts," he wrote last year in a report titled Where Did All the Men Go? So why have so many men stopped working?The explosion in women entering the workforce since the 1960s played a role, though that influence largely leveled off years ago, researchers have found.While many of the dropouts receive some form of government assistance, the generally meager amounts, especially for single men, do not appear to be a primary enticement to stop working.Other theories include everything from the countryís poor track record of reintegrating millions of felons back into the workforce after they leave prison to the influence of video games, on young men in particular.Didem TŁzemen, a senior economist at the Federal Reserve Bank of Kansas City, found the decline in working prime-age men has accelerated since 1996.Her prime suspect: job polarization.From 1996 to 2016, the share of middle-skilled jobs plunged from 54 percent to 43 percent, she found. The middle-skilled occupations generally included routine tasks in sales, administrative services, production, construction, installation, maintenance and transportation.This hollowing out of the middle disproportionately affected prime-age men, leaving many, especially the less educated, with skills that no longer matched the available jobs. (The trend also affected women, but a higher percentage of them benefited by rising into higher-skilled jobs, instead of moving down to the lower-skilled tier.)TŁzemen concluded that without job polarization 2 million more men would be in the workforce. She did not envision those jobs coming back."The types of jobs and the skills demanded in the labor market have been changing dramatically in response to automation and technological advances," TŁzemen said in an interview with the Tampa Bay Times. "I donít see automation losing pace. Iím seeing it accelerating. That means we will continue to lose jobs in those middle-skilled occupations."RELATED: Florida in global fight for talented workersMany of these men have said in government surveys that illness or disability is keeping them out of the workforce, an alarming finding given that none of these men are over the age of 54. TŁzemen, for instance, found more men cited illness or disability than said they were in school, retired or looking after family, combined. And studies have found that nearly half of these ill or injured men regularly use painkillers, often prescription drugs including many opioids.Itís not clear whether disability or illness knocked the men out of the job market or whether the ailments arose after they had already dropped out.Either way, too many appear to be hurting and dependent on painkillers, which presents an additional challenge in getting this cohort back to work. They face the same hurdles as other workforce dropouts ó eroded skills, lost confidence ó but in many cases their bodies also are failing."We know there is evidence that some people who drop out can develop illnesses through time, then become dependent on pain medications, and that then makes them unfit for work," TŁzemen said. "It can be a vicious cycle."MORE: Go here for more Business News Itís too soon to know whether the robust economy will bring enough prime-age men back into the workforce to put a sizable dent in the insidious trend. Just this month, the government announced a steep drop in applications for Social Security disability benefits. That could mean a whole lot of people jumped back into the workforce. Some of them, however, may have just given up on applying because the government has been making the process more difficult. Still others may have shifted to other government programs.What remains evident is that such a large number of stranded working-age men doesnít bode well for their, or our, overall economic fortunes.Contact Graham Brink at [email protected] Follow @GrahamBrink.