Why does everyone get so hung up about having
to take a drug test? If you’re not on vitamin B pills or sleep aides or ibuprofen or had
a poppy seed muffin you have nothing to hide! What’s up science junkies, Julian here for
DNews. If you’re applying for certain jobs or life insurance, you may have to take a
drug test. In some states here in the US applicants for government assistance have to pass a drug
test as well. That’s a bit of a controversial topic but regardless on where you stand on
it, you probably agree that someone who isn’t using illegal drugs shouldn’t be denied
a job or insurance or aid just because the test they took resulted in a false positive.
So these drug tests had better be pretty foolproof, right? Well they may not be up to snuff. It’s estimated
they produce false positives in 5-10% of cases. Judy Stone of Scientific American estimated
that taking into account normal drug use rates, about 9 out of every 1000 people will test
positive for a drug they have not taken. Part of the reason these tests sound a false
alarm is because the list of things that set them off is surprisingly long. The painkiller
Ibuprofen can cause a test to show positive for marijuana, barbiturates, or benzodiazepines.
Cold remedies, hay fever remedies, diet pills, and nasal decongestants can show up as amphetamines.
If you like to unwind with a poppy seed muffin and a gin and tonic, the poppies or quinine
in the tonic water can both trip the alarm for opiates. And of course eating foods with
hemp seeds or taking vitamin B supplements derived from hempseed oil can have trace amounts
of THC, the active ingredient in marijuana. There are many varieties of drug tests and
they all have their strengths and weaknesses. Ideally they strike a balance between accuracy,
cost, and invasiveness. Like a blood test is the most accurate, but a lot of people
have a problem with needles. Hair tests aren’t as invasive but they can be expensive, depending
on how many substances they’re looking for, and some shampoos can throw off the scent. By far the most common method uses urine samples.
The test uses immunoassays, which are biochemicals that bond to specific macromolecules and give
off an indicator reaction. They’re pretty accurate but not perfect, so positive results
often undergo a second test. A gas chromatography/mass spectrometry test analyzes another urine sample,
usually taken from the original. The sample is pushed through a tubular column by helium
gas, and certain drugs pass through it at certain known speeds. Once it gets to the
end of the column, it’s fragmented with ionization and the fragments are sorted by
mass. Again, certain drugs have specific and known fragmentation patterns, so these two
tests together can give scientists a pretty solid idea of exactly what chemicals are present.
The test is more expensive, but the positive results are rarely wrong. Not all drug tests are designed to see if
someone has been using: some are designed to test if an object has been in contact with
illicit substances, or if something is a drug itself. Law enforcement uses these when investigating
drug dealers, but they aren’t perfect either. In 2003 a college freshman flying home for
the holidays was stopped in a Philadelphia airport because she had condoms filled with
white powder in her bag. She claimed it was flour, a gag gift from girlfriends and that
she squeezed them for stress relief, but sadly the tests didn’t vindicate her, coming up
positive for opium and cocaine. She spent 3 weeks in jail and could have gone to prison
for 20 years had more accurate tests not cleared her name. I’m sure she realizes her mistake
now, but for all of you out there let me just reiterate: do not bring white powder in condoms
through airports, it looks a little suspicious. So certain innocuous drugs can trip a drug
test, but that’s not the only risk. For why mixing certain drugs can make you dead,
you can turn to Trace over here. Do you
think the margin of error is good enough,
or is just one innocent person losing their job unacceptable? You can have your say down
in the comments, or on twitter with the hashtag #AskDNews, subscribe for more and I’ll see
you next time on DNews.