Researchers on Thursday said techniques now being developed for analyzing saliva may in the future replace many of the blood and urine tests that now are used to detect drug abuse and disease.
Some law enforcement agencies in Europe already test drugged drivers using saliva and the technique is gaining acceptance in the U.S., said Edward Cone, a Maryland researcher developing equipment for using oral fluids to screen for drug abuse.
"There are a lot of advantages to using oral fluid or spit," he said Thursday at a news conference of the national meeting of the American Association for the Advancement of Science. "It is easily accessible, noninvasive and not embarrassing. You don't have to greet an employee with a urine cup."
Most people produce more than a quart of saliva a day. Researchers have found the oral fluids accurately mirror the proteins that are found in blood and urine. This means that simple spit could provide a diagnostic window on the body in tests not requiring a needle or the embarrassing collection of urine.
Cone said experiments have already shown that spit can be even more reliable than urine tests for drug use screening.
"Drug users have learned how to beat the urine test in a variety of ways," said Cone, an organic chemist who heads up firm near Annapolis, Md. "We haven't found any way to beat the oral fluids test."
At the news conference, researchers said saliva tests also are being developed to detect virus and bacterial infections, and there is the possibility that some cancer tests one day will be based on spit chemistry.
"It has been known for decades that what is in the blood is also present in the saliva," said David Wong, a researcher at the University of California, Los Angeles, Jonsson Cancer Center. He said the National Institutes of Health are now financing studies to develop oral fluids tests that could detect infection and some types of cancer.
First, though, Wong said, science is studying saliva from healthy people. The oral fluid is a complex collection of many proteins, and researchers want to develop an accurate profile of the compounds present in the mouths of normal patients.
Then, he said, researchers will search for the chemical differences that may reflect disease.
"We'll look in the oral fluids for the chemical signature of a disease process," said Wong.
A technique is now being refined, he said, that can detect the telltale proteins produced by oral cancer.
Daniel Malamud of the University of Pennsylvania said his research team has developed a sponge-tipped wand that can collect saliva from a patient and then transfer it to an analyzer that can identify DNA, antibodies and other compounds linked to virus and bacterial infections.
He said laboratory experiments show the technique can detect evidence of infection from the HIV virus and from a bacteria similar to anthrax.
Eventually, he said, science will learn how use saliva to find evidence for any type of virus or bacteria present in the bloodstream.
By Paul Recer