Almost half the population of any given locker room.
An equivalent number, proportionally, to the number of young Americans who have college degrees.
Crack some eggs: This is your national pastime on drugs. According to an anonymous NFL player writing in the current issue of ESPN The Magazine, four out of every 10 of his peers use human growth hormone. And that, in turn, is a serious problem -- at least by the standards of the Steroid Madness gripping baseball, cycling, the Olympics and just about every other avenue of human competition, including chess and poker.
Only, what if that madness is misguided?
What if we're too ignorant to judge the severity of the performance-enhancing drug problem in sports?
What if the madness makes us ignorant, and the single greatest side effect of our ongoing War on 'Roids is that we don't even know what we don't know?
Let me explain.
From the BALCO probe to Congressional hearings to ESPN The Magazine's "Player X" lamenting that HGH use is cheating, we're in the middle of an ongoing drugs-in-sports moral panic, a panic rooted in two suppositions.
First, PED use is against the rules.
Second, PED use is bad for your health.
The former is a vexing ethical quandary, fodder for thought and debate. It's also essentially arbitrary: In sports and society alike, the rules are whatever we decide they should be. Think interstate speed limits. The curse words permissible on network television. Zone defense in the NBA. Whatever the NFL decrees qualifies as a touchdown catch.
Look, if the league pooh-poohs HGH, then Player X has every right to be upset with violators. Same as if it pooh-poohs sack celebrations that fail to comply with the Hays Code.
By contrast, the latter supposition is a scientific question, fodder for observation and hypothesis testing. (You know, like your junior high science fair.) The answers aren't related to who can shout the loudest about the sanctity of the Major League home run record; they're entirely dependent upon how substances such as HGH actually affect the body, day after day, dose after dose.
And that's where our madness may be mucking up our knowledge.
Here's the dirty little open secret about HGH and other performance-enhancing drugs: We have a murky, incomplete idea of the health risks they pose -- particularly over extended periods of time, and especially when it comes to their use by adult athletes.
Only, don't take my word for it.
"Can you hurt yourself with [these drugs]?" says Dr. Charles Yesalis, an emeritus professor at Penn Sate and expert on performance-enhancing drugs in sports. "Yes. But you can hurt yourself with aspirin, with any drug. There is no such thing as a perfectly safe drug.
"We've been using [steroids] safely in medicine for 80 years. In the global sense, they've never been demonstrated to be a major killer like cocaine, heroin, alcohol, tobacco. For something that's been used for so long by so many people, where are all the body bags?"
In his autobiography "Juiced," Jose Canseco lauded PEDs as pharmacology's answer to magic beans, drugs that will make you big and strong without causing any harm. He was mistaken. Experts agree that they're harmful to adolescents. According to the Mayo Clinic and the National Institute on Drug Abuse, anabolic steroid and HGH use by adults has been associated with a series of undesirable side effects, ranging from male breast growth and acne to liver tumors and heart disease.
On the other hand, Yesalis says, the short-term effects of steroid use generally cease when you stop using them. Or, as an American Medical Association doctor told Congress during a 1989 hearing, patients under medical supervision can use the drugs safely.
Meanwhile, Yesalis adds that evidence for "roid rage" -- a much-hyped increase in aggression linked to steroids -- and other psychological side effects popularly attributed to steroid use is largely anecdotal. Moreover, the long-term effects of PED use are unknown.
Not kinda-sorta understood but waiting on additional study to make sure.
Just unknown. Dark side of the moon.
In a climate of hysteria -- in which steroids are culturally demonized and legally criminalized under the same federal statutes that govern controlled substances such as cocaine -- no one has done the basic research commonplace with drugs like ibuprofen. Forget control groups, peer-reviewed studies and much of what constitutes modern medical science. Much of what we presume to know about the effects of PED use comes from surveys of bodybuilders, people who are taking massive quantities of drugs of dubious composition and origin.
"To the best of my knowledge, there has yet to be an epidemiological study of the long-term effects of steroids," Yesalis says. "I proposed to do a study on this in the late 1980s and early 1990s. I submitted that proposal three times. It was rejected three times. I gave up."
What happens when we give up? We panic. We trade reason for emotion, robust facts for hollow moralizing, realistic risk assessment for unchecked fear and unwitting ignorance. We no longer know what we don't know -- a deluded state of mind that can be more dangerous than any PED side effect.
Not convinced? Ask yourself the following:
In the long run, are PEDs more or less harmful to one's health than the repeated concussive and subconcussive head traumas that are commonplace in football?
Are PEDs more or less harmful than bulking up to 350-plus pounds to play offensive and defensive line?
Are PEDs more or less harmful than the powerful painkilling and anti-inflammatory drugs -- including corticosteroids -- given to pro athletes on a daily basis?
Is 40 percent of NFL players allegedly using HGH even a cause for legitimate alarm?
Right now, all of the above are mysteries, casualties of the War on 'Roids. We simply don't know. And that's a pity -- a shame, really -- because they're exactly the kind of questions Player X and his HGH-using peers need and deserve answers to, the sort of information that could help them make rational decisions about both their health and their sport.
Years ago, Yesalis attended a news conference for former Pittsburgh Steelers center Mike Webster. In his post-football life, Webster suffered from a series of mental disorders before dying from heart failure at age 50. He later was diagnosed with chronic traumatic encephalopathy, the same rare neurodegenerative disease found in nearly a dozen other deceased former players.
"I remember Mike standing at the podium, and they asked him, 'Do you ever use steroids?'" Yesalis recalled. "He said, 'What do you mean -- the ones athletes take, or the ones team doctors give you?'"
Patrick Hruby is a freelance writer and ESPN.com contributor. Contact him at PatrickHruby.net.