SEATTLE - Home video shows a Seattle-area flight attendant who got sick, experiencing uncontrollable shaking, headaches and memory loss, after finishing her shift on a jetliner.

"The paramedics were looking at me, monitoring me, and at that point said 'This one needs to go to the hospital,'" she said.

Mysterious illnesses have been reported by flight crews around the world, who believe they are exposed to dangerous fumes aboard aircraft.

It's led to bitter disagreements between unions for flight crews and the airline industry, including Boeing, which says tests show that cabin air is generally safe.

But the long-running debate could be settled soon in a University of Washington genetics lab. Dr. Clement Furlong and his team have been searching for more than three years for evidence that jet engine fumes have poisoned flight crews and passengers.

"I think we're very close," said Furlong.

They've zeroed in on a chemical found only in airplanes, a jet engine oil additive called tricresyl phosphate, or TCP.

Furlong is developing a method to test for TCP in human protein, which looks like a bundle of yarn. He's trying to find one specific strand to which TCP molecules bond and poison.

Just this past weekend, his team identified TCP's unique signature in protein. Now they begin the final step: looking for TCP's biomarker in the blood of people who've been sick.

"These are pilots and crew from all over the world … have samples from Germany … UK," he said. "They describe similar symptoms - nausea, dizziness, headache. Some of them have been off work since their exposure."

KING

Researchers have zeroed in on a chemical found only in airplanes, a jet engine oil additive called tricresyl phosphate, or TCP.

Here's how TCP could find its way from a jet engine into humans. All commercial jetliners, from both Boeing and Airbus, use air sucked in by the engine and then fed to the cabin in what's called a "bleed air" system.

Oil and hydraulic fluid leaks in the engine, which flight crews say happen more often than airlines admit, can send toxic vapors into the breathing air system and throughout the plane.

An Australian documentary reports that swab tests of random airplanes show the presence of TCP in the cabin.

The film was produced by Tristan Loraine, who funded Dr. Furlong's initial research, with his severance money from British Airways.

Loraine is a former captain who believes he was poisoned by bleed air.

"My doctor decided that my health had been compromised to the point that it was no longer safe for me to fly," he said.

But airlines point to a King County lawsuit as one example of the lack of evidence in these types of claims. A jury sided against 26 Alaska flight attendants, saying their illnesses couldn't be linked to the airplanes on which they worked.

In a statement to KING 5, Boeing says the company "continues to work with scientists to improve cabin air, but studies show contaminant levels are generally low."

The woman in the video could never return to her job as a flight attendant.

Karen Burns says her tremors lasted for more than three years.

"The shaking, the memory loss - I lost a lot of my hair, my fair fell out," she said.

Like many flight crew members, she's hoping the UW research will explain why she walked on an airplane healthy and came off sick.

"They weren't able to look in our blood and say this is what did it.  And that's what I think this researcher can do.  And I think it's going to make such a difference," she said.

There have been documented cases of sick passengers, but that's usually when there's a big leak and obvious smell and vapors in the cockpit.

Dr. Furlong's team suspect that flight crews, who spend 750 hours on a plane a year, suffer from lower level exposures to TCP. They're trying to find out if it accumulates in the body.

Boeing's new 787 does not use bleed air technology.