Could Britney Spears have cut her hair to avoid a drug test?

Answers to your questions about the news.
Feb. 23 2007 3:58 PM

Was Britney's Hair Full of Drugs?

Shaving your head to beat the narcs.

Download the MP3 audio version of this story here, or sign up for The Explainer's free daily podcast on iTunes.

Britney Spears.
Britney Spears

Rumor has it that Britney Spears may have shaved off all her hair last weekend to avoid having it drug tested during her child custody battle with Kevin Federline. How much can you learn by testing someone's hair?

A lot. A bundle of hair about the thickness of a pencil can tell chemists what specific drugs someone has used and provide a rough timeline of when she used them. Narcotics like cocaine, meth, ecstasy, and PCP introduce toxins to the bloodstream that are then incorporated into each hair as it forms in the follicle. Urine and blood only retain evidence of these toxins for a week or so, but hair can hold on to them indefinitely. (When administered correctly, hair tests are about as accurate as urinalysis.)


Head hair grows about half an inch every month, so a woman with shoulder-length hair carries around a two-year record of her drug use. To test her, scientists would cut off a strip of about three months' worth of growth and then cut it into pieces for analysis. This segmentation allows them to approach each strand the way a dendrochronologist would approach a tree trunk. Like the cross section of a tree, a strand of hair can store information for thousands of years: In the early 1990s, scientists studying the hair of Peruvian and Chilean mummies found evidence of cocaine use dating back to 1000 B.C.

Hair testing for illicit drugs started in the late 1970s, but the practice did not catch on commercially until about 15 years ago, when improved technology allowed for more-accurate results. (There are still no federal standards for hair testing.) These days the annual market is estimated at $800 million to $1 billion. Psychemedics Corp., the largest provider, sells hair-testing services to more than 2,500 corporations, including police departments, banks, hospitals, and schools.

Drug tests can be done on any body hair—armpit, leg, back, pubic—but head hair is preferred because of its length and relative cleanliness. Although pubic hair may be long enough to provide a few months' worth of information, it is less reliable because of its likely contamination from sweat and urine. Hair from any part of the body might become unreliable if it came into external contact with drugs—for example, if someone spent time in a room filled with crack cocaine smoke. Test results can also be affected by hair color or texture. Studies have shown that a dark strand will take up drug residues more readily than a light one—a peculiarity that has prompted some critics, including the American Civil Liberties Union, to deem the practice racist.

Bonus explainer: Could Britney's ex really force her to undergo a hair-based drug test? No. Drug testing is becoming increasingly common in custody battles as a way to prove a parent unfit or irresponsible, but at this point courts in California only allow urinalysis. Even if Britney lived in a state where hair-based tests were allowed, her newly shaved head wouldn't necessarily get her off the hook. * Federline could still get his hands on the trimmed tresses, which the salon has put up for auction. To use them in court, he'd just have to show a secure "chain of custody" or otherwise prove that the hair being tested did in fact belong to Britney.

Got a question about today's news? Ask the Explainer.

Explainer thanks Bruce Goldberger at the University of Florida and Melissa E. Murray at UC-Berkeley's Boalt Hall School of Law.

Correction, March 5: The original version of this article wrongly stated that Britney could be forced to undergo a hair-based drug test as part of her custody battle. The courts in California might ask for urinalysis, not hair-testing. (Return to the corrected sentence.)


Medical Examiner

The Most Terrifying Thing About Ebola 

The disease threatens humanity by preying on humanity.

I Bought the Huge iPhone. I’m Already Thinking of Returning It.

Scotland Is Just the Beginning. Expect More Political Earthquakes in Europe.

Students Aren’t Going to College Football Games as Much Anymore

And schools are getting worried.

Two Damn Good, Very Different Movies About Soldiers Returning From War

The XX Factor

Lifetime Didn’t Think the Steubenville Rape Case Was Dramatic Enough

So they added a little self-immolation.


Blacks Don’t Have a Corporal Punishment Problem

Americans do. But when blacks exhibit the same behaviors as others, it becomes part of a greater black pathology. 

Why a Sketch of Chelsea Manning Is Stirring Up Controversy

How Worried Should Poland, the Baltic States, and Georgia Be About a Russian Invasion?

Trending News Channel
Sept. 19 2014 1:11 PM Watch Flashes of Lightning Created in a Lab  
  News & Politics
Sept. 20 2014 11:13 AM -30-
Business Insider
Sept. 20 2014 6:30 AM The Man Making Bill Gates Richer
Sept. 20 2014 7:27 AM How Do Plants Grow Aboard the International Space Station?
  Double X
The XX Factor
Sept. 19 2014 4:58 PM Steubenville Gets the Lifetime Treatment (And a Cheerleader Erupts Into Flames)
  Slate Plus
Slate Picks
Sept. 19 2014 12:00 PM What Happened at Slate This Week? The Slatest editor tells us to read well-informed skepticism, media criticism, and more.
Brow Beat
Sept. 20 2014 3:21 PM “The More You Know (About Black People)” Uses Very Funny PSAs to Condemn Black Stereotypes
Future Tense
Sept. 19 2014 6:31 PM The One Big Problem With the Enormous New iPhone
  Health & Science
Bad Astronomy
Sept. 20 2014 7:00 AM The Shaggy Sun
Sports Nut
Sept. 18 2014 11:42 AM Grandmaster Clash One of the most amazing feats in chess history just happened, and no one noticed.