A full-time medical test subject, Nick F. has earned $80,000 participating in some two dozen studies.

Photograph by Michael Lewis Every year, millions of volunteers participate in clinical trials in return for quick cash. A few turn pro. Welcome to the guinea pig underground.

Nick F. was driving a delivery truck in Milwaukee when his life hit a rough patch. He was living in a converted barn and putting every spare penny into paying off a $12,000 debt he had accrued in college. The future looked bleak. So, for a change of scenery, he moved to Richmond, Virginia, where an acquaintance told him there was money to be made as a test subject in medical studies. Feeling desperate, he applied to join a drug trial in Baltimore. The promise: $6,500 for four 12-day stints of blood draws, echo cardiograms, and physical checkups.

That was three years ago. Since then, Nick, 36, has become a full-time guinea pig. He has participated in some two dozen studies, shuttling between test labs in Baltimore; Boston; Fargo, North Dakota; and Trenton, New Jersey. He has earned a total of $80,000 swigging chemically enhanced sport shakes, popping pills laced with radioactive carbon 14, submitting to 36 blood draws over a four-day stretch, and pooping in a box.

"I used to practically faint at the sight of a needle," he says. "Now I give the phlebotomist pointers like, 'My veins roll, so make sure you hold them still.'"

Nick is part of a growing subculture of human lab rats. Each year, US scientists require a total of at least 10 million healthy test subjects, says Adil Shamoo, chair of Circare, a human research watchdog organization. Depending on duration, rigor, and risk, medical studies can pay as much as $10,000 each.

The work isn't demanding, but it can be dangerous. In March 2006, eight male volunteers checked into London's Northwick Park Hospital for a weeklong study of TGN1412, an experimental treatment for rheumatoid arthritis and leukemia to be manufactured by Boehringer- Ingelheim. Within minutes of receiving the first dose, six of them began to writhe in pain, vomit, and lose consciousness, according to news reports. Nurses rushed them to the hospital's trauma unit, where doctors treated them for multiple organ failure. The test subjects lived, but all suffered permanent damage to their immune systems and internal organs. One lost fingers and toes. Another developed signs of cancer possibly triggered by the drug.

Given the risks, most test subjects go in for a one-time score to pay off a debt or finance a vacation. Some stay on the testing circuit for a few months after college or between jobs, until they find a career path. For a few, though, clinical trials are a career path. These individuals endure uncomfortable side effects, lackluster food, and endless poking and prodding in return for a flexible work schedule and minimal responsibility. With diligence, luck, and a willingness to fudge their age and other details to match researchers' requirements, professional guinea pigs can earn $50,000 a year or more.

Nick requested anonymity because researchers are wary of serial test subjects — compounds from past experiments lingering in the blood could compromise their results. "To really make a living at this, you need four things," he says. "A laptop with a Net connection to find studies, a cell phone to call other clinics while you're doing a study, a credit card to book the travel, and an ATM card with a major national bank to deposit your money as soon as you get out." During a particularly busy four-day stretch in 2004, Nick covered more than 2,000 miles, going from Milwaukee to Trenton to apply for a trial at Bristol- Meyers Squibb, to Waukegan, Illinois, for another screening at Abbott Labs, and then, having passed the test at Bristol-Meyers, back to Trenton for more lab work.

Guys like Nick — smart, organized, restless — are typical of a new wave of guinea pigs. "Back in the day, the world of the lab rat was grifters, losers, and hustlers," Nick says. "But even in the three years since I started, it has become more socially acceptable. We're in a culture that's a little more devil-may-care, a little foolhardy." And, hey, if you can't make a living behind the wheel, why not try your luck at the other end of an IV?

Ex-union organizer Robert Helms created the zine Guinea Pig Zero and incited fellow lab rats to demand more compensation during a Merck drug trial.

Photograph by Michael Lewis __Eager to experience __the guinea pig life firsthand, I decide to enroll in a study near my home in San Francisco. I start by searching GPGP.net, a site that lists upcoming studies in the US, Canada, and Europe. (The name stands for Guinea Pigs Get Paid.) Then I stop by BioTrax for online information about the screening process. I learn that signing the required consent form could mean I have to sue to collect additional compensation should something go horribly wrong. However, it wouldn't obligate me to complete a study. I could forgo part of the fee and withdraw at any time.

I'm thrilled to come across a notice on craigslist looking for subjects to demonstrate the impact of the club drug GHB on driving ability; I imagine myself going to raves and then speeding home, a clinician riding shotgun. But the trial is over subscribed. So I settle for a study observing the effects of Stone Age nutrition — the so-called Paleolithic diet — on modern-day Americans of average physical condition. The pay is commensurate with the risk: $200 plus free food for three weeks.

Not long afterward, I find myself marching on a steeply inclined treadmill at the UC San Francisco hospital. A blood- tapping device called a heparin lock protrudes from a vein in my arm, and electrodes are attached to 10 freshly shaved spots on my chest. I huff and puff into a gas mask-like apparatus. Four tubes extend from the mouthpiece, one of which pumps a mixture of acetylene, helium, oxygen, and nitrogen into my lungs. Every two minutes, the study's head researcher drains a few drops of my blood.

After 15 minutes, I'm drenched in sweat and gasping for breath. The exercise physiologist takes a reading. She turns to me with a smile and declares: "Good news! You're unfit enough to be in this study!"

Few test subjects have as much experience as Scott, who, like Nick, requested anonymity to protect his earning power. A 10-year veteran, he has participated in more than 60 studies. Among the highlights: testing a cream designed to numb the penis and spending a week gloriously high on morphine pills. When he's not crisscrossing the country in pursuit of a paycheck, he lives near Miami in a two-bedroom, two- bathroom home. In his spare time — and he has a lot of it — he works on his four-car fleet: a Buick Electra, a Pontiac Fiero GT, a Honda Civic, and the crown jewel, a Lambor ghini Countache (sans engine). He enjoys scuba diving in the Florida Keys and makes sure his schedule is clear during the nation's biggest parties: Mardi Gras in New Orleans, Fantasy Fest in Key West, and occasionally Burning Man in Nevada.

Scott is philosophical about the risk of a TGN1412-style disaster. "I've worked in construction and hit my thumb with a framing hammer," he says. "I've worked as an electrician and seen guys get electrocuted. Being a lab rat is the only work situation where you've got around-the-clock medical attention. It's the safest job I've ever been in."

Finding the next gig is a constant priority. Scott brings his laptop to work and, taking care not to tangle its power cord with the IV tubes dripping experimental meds into his bloodstream, he spends his inpatient hours scouring the Web for trial notices, air fares, and car rentals. He checks out opportunities suggested by fellow test subjects and research recruiters he has gotten to know over the years. He tries to stay away from tests involving radioactive tracers, extensive x-rays, catheters, or tubes in his airways — unless the price is right. When he finds a study worth traveling for, he secures a pre- and post-trial place to stay through the bedroom co-op CouchSurfing.com, a popular site for lining up free lodging.

Scott, 47, won't reveal his income, but a lab-rat colleague estimates he pulls down $30,000 to $40,000 annually. That's little better than a Starbucks barista, but doctor visits are thrown in and the vacation policy is quite liberal. One of his biggest single scores: $9,000 for a three-week study of an asthma medication. He earned every penny. "I had a tube going up my nose, down my throat, and into my lung," he says. "It's hard to have a tube in your lung for 24 hours a day."

Scott prepares for screening sessions, where researchers determine his fitness for a particular study, the way an athlete gets ready for a big game. In the week leading up to the event, he abstains from alcohol, drugs, and poppy seed bagels (the seeds show up as an opiate in blood tests), as well as salt and saturated fats. He cuts calories until his weight falls to within 10 percent of ideal, but he doesn't exercise — that leaves enzymes in the blood that could disqualify him. And while researchers typically require subjects to wait 30, 60, or 90 days between studies, Scott makes it a point to find out how fast the substance being tested breaks down so he can calculate exactly when his blood will be clean enough for his next engagement.

Until then, though, it's off to California's Lake Tahoe for a few days on the ski slopes.

__My own stint __as a lab rat gets off to a rocky start. At the UCSF hospital, a twentysomething research nurse wearing black-framed cat-eye glasses and a lab coat introduces herself and tells me to sit in an armchair and roll up my sleeve. Unwrapping a hypodermic needle, Christina asks if I tend to black out easily. I'm not a huge fan of needles, I reply, but I've never passed out while having blood drawn. "That's good," she says breezily, "because there are a lot of blood draws in your study."

She presses the needle into my left inner forearm just below the elbow. I grimace at the pinch. A mild prickling sensation runs across my scalp. "That's funny," Christina says. "I got a great initial spurt, and then your vein just sort of closed up."

She tries my right arm, and I can tell by the satisfied noise escaping her lips that she hit the mother lode. I make the mistake of looking; crimson fluid wells into the collection vial. The room tilts, and I mumble something about going down.

The next thing I know, the study's principal investigator, Lynda Frassetto, is peering at me with a concerned look. I apologize for passing out. "You didn't pass out, you just got a little woozy," she assures me. "Now that we've got the IV in" — I glance over and, sure enough, a tube protrudes from my arm — "that's it for needles today. Do you think you're feeling up to some exercise?"

__Guinea pigging tends __to be a lonely occupation. The inpatient tests favored by professionals — "somewhere between prison and sleepaway camp," as Nick puts it — create bonds of shared hardship, but those relationships rarely outlive the experience.

It took Robert Helms to bring the community together. A house painter and armchair historian with a special interest in anarchism, Helms was working as a union organizer in Philadelphia during the early 1990s when friends in the local anarchist scene started earning extra cash by renting their bodies to universities and drug companies. He signed up for a couple of studies and eventually concluded that, with a few thrifty lifestyle choices, he could shift to the slow lane of the rat race.

Which is not to say that he quit organizing. An inveterate rabble-rouser, Helms considered what it would take to unionize the other test subjects at his first few trials. But he realized that the community was much too fragmented.

To build solidarity, he started a news letter. In 1996, with help from a friend who worked at Kinko's and ran off free copies after hours, he launched Guinea Pig Zero, a zine inspired by the amateur workplace tell-alls Temp Slave! and Dishwasher. GPZ featured first-person horror stories of clinical trials gone wrong, histori cal accounts of early human experiments, and tips on where easy money and gentle research nurses could be found. Cartoon guinea pigs decorated the pages — munching pills, manning machine guns, and declaring, "Work is for saps."

Letters and subscription requests trickled in from hundreds of volunteer test subjects across the US. Doctors and medical libraries signed on. Booksellers as far away as Paris and London requested copies to sell on consignment.

Helms continued to publish GPZ until 2000 and kept guinea pigging for three more years. At that point, he turned 46 — a year older than the cutoff age for many clinical trials — and retired from active duty. He played the role of labor leader right to the end. During one of his last trials, he incited his fellow lab rats to flex their collective muscle against Merck, which was investigating the effects of an antianxiety drug. "The guys weren't allowed to drink during the Christmas holidays," he says. "Also, it involved a lot of fecal collection. Then Merck tried to hurry the study into a smaller period of time."

Helms drew up a petition listing the ways in which the trial had deviated from its description on the consent form. The lab rats hinted that the entire group would walk out unless Merck paid each subject $1,500 more than the $3,200 originally agreed upon. He passed the document around for signatures, taking care to put his own name in the middle of the list to avoid being pegged as a troublemaker. The gambit worked. "At the eleventh hour," he says, "they gave us an $800 raise."

__I keep Helms' victory __in mind as I suffer the indignities of research into Paleolithic gastronomy. The study's prehistoric regimen is sort of like Super Size Me in reverse: a bland, unvarying menu of grain-free, virtually dairy-free, unprocessed food for 17 days. Each morning, I drop by the hospital for a breakfast of broiled pork loin and pineapple. Afterward, a staffer drags out a cooler on wheels, packed with five more Paleolithic meals, to be hauled around and eaten by the end of the day. I subsist on carrot juice, tomato juice, whole tomatoes, large lettuce leaves, shredded tuna, more lettuce, chicken and broccoli, and parsnips. No salt.

But the food isn't the worst of it. The study demands several days of frequent blood draws and around-the-clock urine collection. During those times, I carry a 1-gallon plastic container of pee with me everywhere I go.

On the third day of testing, I'm seated in a waiting room watching blood seep through a band-aid from a puncture in the back of my hand. The wound is the result of the latest of five consecutive unsuccessful attempts to draw a vial of oxygen-rich arterial blood. ** I decide to quit the study. I can't endure any more needles.

Frassetto, the principal investigator, enters the room. "Something terrible has happened," she sighs. My pulse quickens. Contaminated syringes? Parasites in my blood? No, her calamity turns out to be my good fortune. Federal approval for the research has expired, and Frassetto needs to reapply. The study will stop immediately and resume when approval comes through — a reprieve of three weeks.

I use the time to catch up on my reading. In a Guinea Pig Zero anthology published in 2002 by Garrett County Press, I come across a glowing account of a drug trial, written by a female lab rat who happily describes her experiences with needles. For some reason this helps, and a few weeks later I return to the study determined to regard the blood draws not as an imposition but as part of a process I have undertaken willingly — simply part of the job. I come up with a phrase that I use to steel myself before every session: "Let's get that blood out!" It works. The nurses have much more success keeping my veins open, and I stop feeling faint.

Ten days into the resurrected study, on day five of the diet itself, I'm seated in a conference room sipping my once-daily cup of coffee and watching SportsCenter. For the 10th morning in a row, I've left my wife at home to feed, change, and dress our infant son and get herself off to work. And it hits me: The stress and strain of life has fallen away. It's peaceful here, away from the hustle-bustle of home and work. This is guinea pig life at its finest.

Toward the end of the trial, I show up early for work. There's a lot to do: the usual blood draws, a rerun of the treadmill test, an ultrasound of my blood vessels, and, finally, a body composition test. The diet has been a ringing success in personal terms. I've lost 15 pounds (officially 6, but I sneaked extra clothes onto the scale to avoid having to lug around the growing portions of pork and pineapple they heaped on my plate as my weight fell), my cholesterol has dropped by 72 points, and my blood pressure is significantly lower.

The final session is uneventful, just one last pork-and-pineapple breakfast in front of the TV for old times' sake. There's no exit interview, no farewell party. Frassetto hands me my $200. I sign my name in the clinic's logbook. Christina barely glances up from her desk as I say good-bye. I stuff the money in my pocket and step out into the street.

Contributing editor Josh McHugh (www.joshmchugh.net) wrote about prosthetic legs in issue 15.03.

* Correction, Thurs May 10 12:00:00 EST 2007

The wound on McHugh's hand was not caused by multiple failed blood-draw attempts by the UCSF clinical nurse named Christina, as originally reported; it was the result of other nurses' attempts. (Return to the corrected text)