Array of tests can track drug use

There's more than one way to catch a drug abuser.
Investigators checking for drugs or alcohol in a suspect's
system have developed a wide array of reliable tools in recent
years.

The most common is the chemical urine test, which is often used
in hospitals. Such testing usually will reveal drug use that
occurred within the previous five days.

Yet researchers have found that some drugs, including
marijuana, can sometimes go undetected in urine testing. More
concrete results, they say, come from blood tests.

"Marijuana is subtle, but careful blood tests should pick it up
if the suspect has used the drug within the past 30 days," said Dr.
Edward J. Newton of the University of Southern California School of
Medicine.

"We didn't have these tests 20 years ago," Newton said.
"Nowadays, if there's even a trace of it, we're probably going to
find it."

Unlike blood tests for alcohol, which are used by law
enforcement agencies in many states, blood tests for marijuana do
not detect the amount of the drug in a person's bloodstream.
Results record only the presence or absence of marijuana. Any
amount is considered enough to render a suspect impaired.

Researchers also have been working to find more reliable
indicators of drugs. To date, they've tried hair, sweat, breath and
saliva.

The advantage of these tests is that sampling material, like a
stray hair or a swab of saliva from a person's mouth, is much
easier to collect. The disadvantage is the possibility of the
samples being contaminated.

In 1990, an experiment in a Grand Rapids lab yielded promising
results for some new methods.

Using urinalysis and hair testing, scientists compared 774
samples. They found 2.7 percent of the urine samples were positive
for the presence of drugs. About 18 percent of the hair samples
showed drug use, leading researchers to conclude that hair testing
might be the indicator of the future.