TESTS ON TRIAL
Jobs and
Reputations Ride on Unproven Drug Screens
Drug tests don't lie,
people do. That's what Michelle Dunson used to
think back when she
administered urine tests for a temp agency near
Toledo, Ohio. Sometimes when
she told applicants they'd failed, the
response would be wide-eyed silence,
then tears and denial.
She offered them tissue, but little
sympathy.
Dunson later took a job with Whirlpool, where she was injured
two
years ago. When she returned, she tested positive for an opiate
and
was fired-even though a note from her doctor outlined
her
prescriptions for a nonnarcotic painkiller, which she believes
threw
off the test. She has a wrongful-termination suit pending
against
Whirlpool, which stands by its testing. "I feel tremendous guilt
now
when I think of those who came to me nearly hysterical, saying
they
did not do drugs," says Dunson. "I think: My God, at least a few
of
them were probably telling the truth."
Dunson can be forgiven for
believing drug test results were the gospel
truth. The tests are often
heralded as infallible, and many private
and government employers, along with
school principals and judges, put
their faith in them. Half of major U.S.
firms now test their
employees, and more than 500 school districts have
screening programs.
But reliably picking up drug traces that linger days
after a user's
last high, while ignoring contaminants and similar-looking
compounds
in medicine and food, is a tall order for even the best technology.
In
the real world, technical glitches can mean mistakes-so-called
false
positives.
Wide Net.
For employers who
test to deter drug use, which they say
leads to a safer, more productive
workplace, so-so accuracy might be
enough.
But it comes at a high cost
in reputations and livelihoods for those
falsely accused. "Innocent people
are being mislabeled because of
unreliable products designed to cast a wide
net," says Steven Karch, a
medical researcher and author of Karch's Pathology
of Drug Abuse.
The error rates are likely to rise. While the
traditional
method-lab-based urine testing-can be highly reliable when
done
carefully, the fastest-growing segment of the drug-testing
industry
consists of newer and often more error-prone tests.
On-site
urine testing appeals to private employers because it gives
results in
minutes and can cost as little as $3 per screening.
Yet studies of the
cheapest of these tests, designed to pick up a
single drug type such as
amphetamines, show they give the right answer
as little as one third of the
time. Other new tests, which rely on lab
analysis of hair and sweat, can be a
powerful probe of drug use-but
can also be fooled by stray drug molecules
from the environment. All
these tests may get a major boost from the proposed
new federal
guidelines for drug testing, expected to be published later this
year.
The rules, which serve as the model for many state and
private
employers as well, will allow new tests, including on-site
urine
screens and lab-based sweat patch and hair tests, to be used
for
screening 10 million federal workers and contractors.
Currently,
laboratory urine testing-the "gold standard" test-is the
only type allowed
for federal employees.
Samples are probed with antibodies for THC
(marijuana), cocaine,
opiates, PCP, and amphetamines, and checked to be sure
they aren't
doctored or too dilute.
When a worker tests positive, the
federal program mandates a second,
more accurate confirmation test called gas
chromatography-mass
spectrometry, GC-MS, along with an interview with a
medical review
officer to be sure that another substance isn't causing a
false positive.
The sample's chain of custody is carefully documented
as
well.
Even GC-MS is not perfect, however.
The test works by
extracting and heating molecules from a sample and
using an electric field to
separate and identify them. Kent Holtorf, a
physician and expert on
drug-testing accuracy, says he got 1,500 calls
last year from people asking
for help with what they said were lab
errors.
He says that when a lab
uses GC-MS to identify the entire range of
molecules, it is 95 percent to 99
percent accurate. But Holtorf says
labs don't always use the equipment to its
full advantage. "Accuracy
rates are going down, not up, as employers contract
with the
lowest-bidding lab," he says. It's cheaper to use GC-MS to look
only
for a few fragments of the drug molecules, which raises the risk
of
mistaking legitimate medicines, herbs, and foods like poppy seeds
for
illegal drugs.
The drug-testing industry dismisses these concerns.
"People always
come up with cockamamie stories about how their test result is
wrong,"
says Paul Rust, a vice president at Quest Diagnostics. "But the
GC-MS
process is 100 percent accurate." Not quite, says Michael Martin,
who
is HIV-positive and takes the prescription drug Sustiva.
The
Worcester, Mass., resident says he had to take a pre-employment
urine
test after he was offered a job at Sears. He presented a
doctor's
letter saying his medication could cause him to test positive for
pot.
When just that happened, Sears rescinded the offer. "I want to work
so
badly I can taste it," says Martin. "But I can't stop taking
my
prescription just to test clean."
Sears, which is investigating
Martin's case, says its policy is to
confirm positive results with a second
test. But at many companies,
employees who fail the initial screen get no
second chance. "Most
employers, even those who use a lab, don't confirm
positives on
pre-employment tests," says David Evans, director of the
National
On-Site Testing Association. "It wouldn't be a financially smart
thing
to do." And, in most cases, it's perfectly legal not to. There are
no
regulations, other than a smattering of state laws, regarding
testing
of nongovernment workers.
Nor has there been tough scrutiny of
the newer drug-testing
technologies. "The lack of scientific studies on these
devices is most
surprising," says Amanda Jenkins, coauthor of the new book
On-Site
Drug Testing. The U.S. Food and Drug Administration will approve
a
test based solely on a company's own studies.
Still, drug-testing
veterans, some independent studies, and even the
makers' own data suggest
that three leading "alternative technologies"
can be disturbingly error
prone.
On-Site Testing.
Like lab assays, these
tests work by combining urine with antibodies.
If the test is negative, a
line appears on a test strip.
But seeing the lines can be a judgment
call, and some products are
especially hard to read. "We stopped using a few
tests because some
people would see a line where others wouldn't," says Brian
Walters of
Premier Drug Testing in Russell Springs, Ky. In one study, 17
common
on-site tests were used to analyze specimens; most contained either
no
drugs or trace amounts.
The accuracy ranged from 52 percent to 82
percent.
Sweat Patch.
In this test, a
Band-Aid-like patch attached to the skin collects
sweat for up to seven days
and is later lab-tested for drug residue.
It's tough to cheat-if the patch is
removed, it can't be
reattached-and the test is often used in parole,
probation, and
child-custody cases to determine whether a user has
been
rehabilitated. But studies by the U.S. Naval Research Lab and
the
patch manufacturer itself showed that drug molecules from
outside
sources-such as clothes or other people-can penetrate the patch
and
trigger a false positive.
The sole maker, PharmChem, says both
studies exposed the patch to
unrealistically high levels of contamination.
"Those were just not
real-world situations," says Neil Fortner, PharmChem's
chief
scientific officer.
But a federal court in New York recently
ruled that the sweat patch
"is susceptible to outside
contamination."
Sheryl Woodhall thinks that's what cost her custody of
her two
youngest children. She wore the patches to prove she was no longer
a
methamphetamine addict. But after she flunked seven of eight tests,
her
kids were placed permanently in foster care, and she was forbidden
to contact
them. During the same period, Woodhall says she tested
negative on dozens of
urine screens, done under observation so she
couldn't
cheat.
Hair Tests.
Lab analysis of 1.5-inch long
strands of hair cut near the scalp can
give a drug history covering 90 days,
compared with only a few days
for most drugs in urine
tests.
Psychemedics, the largest hair tester, says 140 schools and
2,300
corporate clients use its services.
But hair testing is also the
most controversial of the new
technologies because of concerns that it is
discriminatory and can be
thrown off by contaminants. Several studies by the
National Institute
of Drug Abuse show that some drug molecules, whether
ingested or
picked up from the environment, have an affinity for the
pigment
melanin and bind more strongly to dark hair than light. "If
two
employees use cocaine, the blond might barely test negative, and
the
other will get caught," says Robert Stephenson of the Substance
Abuse
and Mental Health Services Administration.
Raymond Kubacki,
president of Psychemedics, dismisses concerns about
discrimination and says a
series of washes removes contaminants from
hair samples. "You could be in a
crack den and you won't test
positive." But Ronnie Jones, a Boston police
officer for 20 years,
blames contamination for a marginally positive result
for cocaine he
got on a hair test last March. Jones-nicknamed "the deacon"
for his
Bible reading and clean living-submitted a second hair sample the
same
day, which tested negative. Although the company downplays
the
contamination risk, Kubacki says it has begun testing for
drug
metabolites, the fingerprints left after drugs are processed by
the
body, rather than just the parent substances.
So far there have
been few technical challenges to another new test,
which relies on analysis
of a saliva sample.
Because drugs show up in saliva more quickly than in
urine, hair, and
sweat, the test may reveal whether a person is currently
high, making
it useful for post-accident testing.
But it is just
beginning to catch on. And like the other tests, it
will get its real trial
in the real world, where jobs and reputations
will hinge on the right
answer.
__________________________________________________________________________