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  Hair Test for Marijuana Reliable or Fair?
Posted by FoM on January 09, 1999 at 07:02:05 PT
Q:How accurate is the hair test to detect Marijuana use?

A:Hair testing has become standard policy in many corporations as a means to screen job applicants and workers for possible drug abuse. It has many advantages over urine tests and is less invasive and more convenient.

The hair test has received notoriety on the Coast partly due to its use by one soon-to-open casino. Rumors have taken flight that marijuana use from as far back as five years might be detectable in hair in some cases. That appears to be exaggerated.

Hair analysis is said to be able to detect drug use over the previous three months or so and can even establish a timeline of use. In contrast, the range of urinalysis detection is much shorter. Depending on the drug and many other factors, urinalysis detects drug use over only the previous two days to three weeks, and it's not difficult to cheat on urinalysis tests.

Unlike urine tests, hair tests can't detect recent drug use, since it takes several days for drugs to show up in hair. Urine tests easily detect marijuana, but have a tougher time spotting cocaine and heroin, while hair tests do just the opposite: they easily detect cocaine and heroin but have a tougher time with marijuana. In these ways, the two types of tests can be complementary.

Psychemedics Corp. has patented a hair analysis technology used by more than 1,300 companies, including casinos, the Federal Reserve System and General Motors.

At least one private school in the New Orleans area has adopted hair testing for the entire student body.

The hair test can be used to detect the use of marijuana, cocaine (also crack), narcotics such as heroin, methamphetamine and PCP (angel dust).

You can find the company's over-the-counter hair test kit called PDT-90 in most drugstores.

There's little doubt that hair testing can catch more drug users than urine testing. Out of more than 700 job applicants, one company found 2.7 percent positives with urinalysis tests. When hair tests were used on the same group, 18 percent came up positive.

As hair testing makes more inroads, there are worries that it may sometimes point the finger at innocent people, such as children of drug abusers or police working narcotics details, who may be exposed to drugs without taking them.

A scientist with the Naval Research Laboratory in Washington said he's found that hair tests on young children of cocaine-using moms often come up positive. He speculates that small traces of the drug get onto the children's fingers or those of the mother and finds its way inside their hair follicles via perspiration.

Another concern is that drug traces might last longer in thick, dark hair.

"Black hair seems to accumulate far more cocaine than light-brown or blond hair," said Edward J. Cone of the National Institute on Drug Abuse. There's a "good possibility," he said, that "ethnic groups with dark hair are going to test positive for the drug more often."

"Hair testing may turn out to have a complementary role in workplace testing," said Robert Stevenson, deputy director of the Workplace Programs Division of the federal Center for Substance Abuse Prevention.

"But we have yet to resolve remaining questions about its fairness and the ability to interpret results consistently."

Richard Harkness, a consultant pharmacist living in Ocean Springs, writes nationally on health care topics and is a former columnist for Drug Topics magazine. You can write him at 1224 King Henry Drive, Ocean Springs, MS 39564; or e-mail is Selected questions will be used in the column.

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Comment #3 posted by jose melendez on June 13, 2005 at 08:16:30 PT
test THIS!
Here is my suggestion.

Choose a different job very close to home, where the employer does not infringe upon your privacy rights. Try to pick something that you love doing, even part time or with less pay.

The commute time at whatever hourly rate you normally charge makes a huge difference in attitude and net income. Also, remember that they are not paying you for your time off.

What they are doing is almost certainly unethical, but regardless, why would you want a job where you have to lie to your boss?

Anyway, here are some job sources that might match your interests, assuming the quality av in your email address means audio visual. Check also on

Drug war IS crime.

Jose Melendez Concerned Citizens Coalition to Criminalize Prohibition 888 247-8183

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Comment #2 posted by Sometimes on June 13, 2005 at 07:37:46 PT:

Hair Test for Job App.
Hello. I am currently applying for a position in which I am being ask to take a hair-based drug test. Probably 1-2 months ago, I smoked about one half of a joint. I do not use any other drugs and prior to this instance, I had not smoked marijuana in about 3 years. I am 36, in good health, thin with high metabolism. I am very nervous about this test and how it may affect my future (or lack thereof) with this company. I would greatly appreciate and value any comments/suggestions.

Thank you.

[ Post Comment ]

Comment #1 posted by cheri on September 20, 2000 at 10:17:34 PT:

hair follicle testing
is there anything that can be mistaken for cocaine in your hair follicle's?? husband does not use drugs however he came up positive for there something that he is drinking or eating or some kind of herbal drink that would show up as cocaine when it is actually not?..can you find cocaine in the blood stream??...i need help asap!!!

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