Elias Youngquist, 21, holds up the check he earned after giving himself up for medical research to pay for the engagement ring displayed on the laptop screen next to him. David Martin for Al Jazeera America

LINCOLN, Neb. — Elias Youngquist knew which engagement ring he wanted to buy his girlfriend, but the college senior didn't know how he was going to pay for it. The 1935 vintage diamond ring with an ornate band cost $1,020.

Then he learned of a part-time job that would cover the price of the ring and then some — in just a few hours. The only caveat: the gig could cause suicidal tendencies, psychosis, insomnia and hypertension. He signed up anyway.

Youngquist, a 21-year-old journalism student at the University of Nebraska, became a test subject in a clinical trial for an antidepressant. By doing so, Youngquist joined the front lines of pharmaceutical testing: a Phase I trial, the first step in the U.S. Food and Drug Administration's drug-approval process.

In his role as human guinea pig, he spent two weekends at Celerion's dormlike test site in Lincoln, Neb., swallowing a small white pill at 7 a.m. each Saturday under the watchful eyes of a doctor and two staff members.

"I've spent worse weekends," said Youngquist, a Lenox, S.D., native.

He returned early each morning the following week to have blood samples taken.

Phase I trials, involving 20 or more subjects, are used to determine whether a drug is safe and to learn possible side effects. Youngquist arrived on a recent Monday morning and reported, reluctantly, that he'd been gassy. Now, he said, his chart reads: "Youngquist/Flatulence."

He is part of an underground of people in Lincoln and across the country who step up time and again to get poked, prodded, injected and otherwise sickened as human guinea pigs in clinical trials. The pay is good — sometimes $2,000 or more for a week's work — but the risks can also be high, with some participants suffering lifelong health effects.

If a drug is deemed safe, it can advance to Phase II and Phase III trials on patients to see if it's effective and determine the optimal dosage. These trials typically involve thousands of patients.

Celerion, which is headquartered in Lincoln, recruits in coffee shops in this college town with posters asking, "Spare time this summer?" The company website says test subjects "help people in your community and around the world."

Despite the appeal to altruism, money appears to be the prime motivation for people who sign up.

Tommy Dornish, 22, said the more than $20,000 he made taking part in clinical trials at Celerion helped pay for books, tuition and living expenses while he attended the University of Nebraska. Without them, he said, he would have had to take time off from school to get a full-time job.

He is participating in his eighth study in three years, and he has experienced significant side effects only once, when he suffered jaundice, which turned his skin and the whites of his eyes yellow. He cautions, though, that guinea-pigging isn't for the squeamish, requiring blood draws as often as every 15 minutes.

Dornish said two women were kicked out of a recent study after they couldn't finish a high-fat breakfast — two fried eggs, buttery hash browns, whole milk, buttered toast and bacon — in the allotted 20 minutes.

"I liked it, but a lot of people thought it was gross," he said.

Dornish, who has graduated and now works in Lincoln as a loan officer, said he'll keep doing the studies as long as they let him. But his enthusiasm does have its limits.

"There's a study with a spinal tap," he said. "I don't want to go anywhere near that. Heck, no."

Mark, 29, who asked that his last name not be used, said he was lazy and didn't feel like getting a job when he signed up for a Phase I trial involving a diabetes drug. He experienced what he describes as the "head cold from hell" and quit the study when his snot reached the ground.

"I just felt like my immune system was getting weaker and weaker," Mark recalled, adding that he was sick for two weeks after leaving the study.

Another frequent test subject in Lincoln, an Iraqi immigrant who requested anonymity, has permanent needle marks on his arms from all the blood draws.

"Sometimes people think I shoot up," he said.