What Do Drug Tests Really Tell You?

I’m behind the curve again, having had final exams to grade and such, but with all the talk about Jeremy Mayfield’s suspension for failing a drug test, I had to write something about drug tests and what you can reliably conclude from them. Disclaimer: I’m not a medical doctor, but even a casual perusal of the drug-testing literature suggests to me that drug testing is a lot more complicated than the black-and-white results people would have you belive. NASCAR has a drug-testing policy that allows them to test urine, blood, saliva, hair or breath if there is “reasonable suspicion”. Random competitor tests are also done on a weekly basis.

What is Being Tested For?

NASCAR crews (not drivers) were given a list that includes:

  • Seven different amphetamines, including methamphetamine and PMA, a synthetic psychostimulant and hallucinogen.
  • Three drugs classified under ephedrine.
  • 13 different narcotics, including codeine and morphine.
  • Ten different benzodiazepines and barbituates.
  • Marijuana, cocaine, zolpidem, nitrites, chromates and drugs that can increase specific gravity.

Amphetamines are ‘uppers’, which decrease fatigue by increasing levels of the stress hormones norepinephrine (attention and responding/fight-or-flight reactions), and the neurotransmitters serotonin (modulates anger, aggression, mood, metabolism, etc.), and dopamine (increases heart rate and blood pressure).

Ephedrines are stimulants, appetite suppressants, decongestants. The molecule Ephedrine looks very similar to amphetamine. Psuedoephedrine is like the left-handed version of ephedrine and that’s what’s in over-the-counter decongestants like Sudafed.

Narcotics is an imprecise term that usually refers to anything that deadens the senses. Codeine, morphine, heroin, etc. fall in this category.

Benzodiazepines and barbituates are downers, which do the opposite of amphetamines and decrease the action of the central nervous system.

Prohibiting marijuana, cocaine and zolpidem (a sleep aid that is in things like Ambien) is obvious, but the last part doesn’t make sense at first reading. I believe the idea is that nitrites and chromates can be used to adulterate a urine sample to try to hide drug use. “Drugs that can increase specific gravity” means the specific gravity of urine (as was pointed out by a poster on rowdy.com). One way of checking for adulterated samples is measuring the pH, temperature and specific gravity (the density of the sample relative to water). If the values are outside of a specified expected range, then the sample is suspect. So the latter part of that rule isn’t about illegal substances, it’s about things that you might take in order to hide the use of illegal substances. For example, if you drink large quantities of water (1-2 liters), most of it comes out in the urine and that dilutes anything elkse in there.

Needless to say, you don’t want anyone in a position of responsibility on one of these substances. Note that this list is for the crews. The drivers don’t have a list, but you could safely assume that all of the substances mentioned are off-limits, plus some. NASCAR reserves the right to test for anything they think could potentially impair a driver on the track.

How Do You Tell If Someone’s Used These?

A sample (usually urine) is collected and split into two parts called the ‘A’ sample and the ‘B’ sample. The A sample is tested with a chemical test called an immunoassay. Immunoassay (IA) tests, as I’ll describe in a moment, are more general tests. The B sample is stored and there are specific protocols for how the sample must be stored. If the IA test shows one or more positives, then the B sample is brought out and tested using a more sophisticated test called Gas Chromatography-Mass Spectroscopy. If the B sample tests negative, then the test is generally regarded as negative. If the B sample tests positive for one of the banned substances, then the driver is notified and disciplinary action is taken.

Immunoassays work sort of like a jigsaw puzzle. There are antibodies (detectors) and antigens (targets). The two types of molecules bind to each other.

The molecule in the upper left of the picture above is our detector molecule. The circle represents something that can be detected – a fluorescent molecule, a magnetic bead or something similar. The molecules on the right-hand side are the molecules in the sample to be analyzed. Our detector molecule has a binding site – the fork pointing to the right, and that binding site will allow it to only link to specific shapes of molecules. (In reality, the binding is chemical, not by shapes, but I find the analogy to shapes easier to understand.) Our detector will only bind to triangle shapes, but there’s a problem here in that there are blue triangles and green triangles. Immunoassays are very sensitive – they’re good at detecting things, but they are not always as specific as we might like. The green triangles might represent a banned drug, while the blue ones are harmless — but both bind to our detector molecule.

That’s OK because we have the B sample and if the A sample shows that there might be something there, we then analyze the B sample using a more specific technique. Gas chromatography is used to separate molecules by weight. The sample is run through a column so that all the molecules with the same weight as the target substance are collected. We do this in elementary school with kids and pens. The analogy we use is to make two rows of kids the same length. Two kids are chosen to be ‘sample molecules’. The first kids is allowed to just walk down the row. The second kid must shake hands with everyone in the row as he walks. We start both kids at the same time and, not suprisingly, the student who has to shake hands takes a lot longer to travel the same lengths as the student who doesn’t. In GS, the sorting is done by weight, so all the molecules with the same weight as the suspicious molecule are separated.

The molecules are then heated. All molecules break into fragments in rather predictable manner when heated, so the mass spectrometer detects fragments and you can infer what the molecule was before it was broken up, and how much of it there was.

The Caveats

False Positives

A false positive is when you find that the molecule you’re testing for is there, but it isn’t really. There are A LOT of things that cause false positives. For example, buproprion (an anti-depressant) can cause a false positive for amphetamine. So can an awful lot of other things. Apparently, if a driver has a prescription for one of the conflicting substances, they just have to have their doctor contact the drug testing doctor and things are OK.

To make it more complicated, some drugs are quickly metabolized (broken up) by the body. Amphetamine passes through the body into the renal system (the urine) mostly unadulterated by the body; however, other drugs are transformed by the body and what you test for are the products of metabolizing the drug. Some drug tests are therefore very indirect.

Chain of Custody

The lab handling the analysis must follow proper procedures and be very careful to make sure that they don’t mix up samples or cross-contaminate one sample with another. While you hope that all labs are careful, there are plenty of incidences in which labs have been found to have shoddy procedures.

A problem, of course, is the time scale of the tests: urine tests can detect drug use from timescales of hours to days. NASCAR didn’t relate that there was a problem with the test for a few days, so taking another urine test after notification wasn’t a possibility. It is, however, possible to test for drug use in hair, which can reflect drug use over a period of weeks to months. NASCAR allows no appeal, which seems to me very misguided. NOTE ADDED: ESPN is reporting that Mayfield is having hair samples tested.

Conflict of Interest

The doctor that NASCAR has contracted with to conduct the drug testing also owns the lab at which the tests are done. This seems to me to be a clear conflict of interest. At the very least, NASCAR should have an independent person versed in drug testing overseeing the test. If I were NASCAR, I would have the samples tested at two different labs, preferably one lab chosen by the person being tested. This is too important an issue to leave to the possibility of a lab screw up – and the papers are full of people being let out of jail because of mess ups in testing laboratories. There are a lot of places for things to go wrong. It doesn’t sound like that’s what happened here because of Mayfield’s defense that an interaction between a prescription drug and an over-the-counter drug is responsible for the positive; however, sometimes the perception of unfairness – totally independent of the reality – is damning.

The other conflict of interest issue is whether NASCAR should make the drug for which the positive test was found public or not. One the one hand is Mayfield’s right to privacy. He may be taking antidepressants and not wish to have that revealed; however, if Mayfield waives that right, this isn’t an issue. The latest statement Mayfield issued (from an infield hospitality trailer during the All-Star Race) says that NASCAR hasn’t told him what drug he tested positive for, while NASCAR claims that he’s been told verbally on three occasions the identity of the drug. This is extremely troublesome for two reasons. First, if he’s found guilty, he ought to at least know the evidence against him. Second, how can he claim a reason for why he tested positive if he doesn’t know what he tested positive for?

Can We Make a Judgement?

No, we can’t because there simply hasn’t been enough data released to make a determination. The people who are assuming guilt or innocence are doing so based on their opinions, not on evidence. More balanced are the writers calling for greater transparency. If Mayfield follows up on his threat of legal action, the truth may come out. Until then, we are pretty much stuck in the dark, trying to make decisions based on who we deem to be most trustworthy – a pretty poor way to do science, especially when a man’s reputation is at stake here. Let’s hope that the facts are brought to light and we can all make a conclusion based on real evidence

NOTES Added: Jeremy claims he doesn’t know what substance he tested for. Dr. Black claims he’s told Jeremy personally. Jeremy says he hasn’t gotten it in writing. Dr. Black says that NASCAR issues written reports, not him. NASCAR says that they aren’t aware Jeremy wanted a written report. Come on folks. Argh!

Also see: Marc at Full Throttle has a great post on the issue – well worth reading.


  1. Thanks for the lesson on drugs and testing, Diandra; It was very informative. The one thing I would like to say is that again, NASCAR has used the iron fist of their dictatorship to make what was a bad enough situation into one that each day is causing them to look more and more arrogant and inept. I’m not a fan of Jeremy, but everyone deserves to know what the charge is against them and I honestly do not think he has been accorded that consideration. If I’m wrong, I’ll be the first to apologize to the Bubbas. But as it stands now, I’m thinking the Claritin D sponsors are having a say in all this nonsense.

  2. Anytime a person takes a drug test a printed copy can be obtained of the test. NASCAR states that they are protecting Mayfield by not releasing the test results. NASCAR and the lab will only verbally give him the test results. They will not provide him with a print out of his test results. So, are they protecting Mayfield or is NASCAR protecting it’s ownself?

  3. Diandra,

    Great explanation. From watching Forensic Files, I knew about the GC-MS and was wondering if that is always used in drug testing.

    Good point about the lab and the owner. I didn’t even think of that. How cozy.

  4. nascar is takeing this to far mayfield may not be liked in the garage but, in lancaster,sc we do . i guess that if your not in the driver seats of 48,14,39,25,09,88,5, and still cheating, that you have to bring something else to the table. so they have picked on the little guy. who is not guilty . the past 2 races there where alot of empty seats,and this drama has made national news. what better way to sell seats than the nascar drama mill……

  5. Jeremy said that it was illegal for the same lab to test both the “A” and “B” samples and I was curious to know if that is true or not. I would think that at the very least Jeremy could request the “B” sample to be tested at another lab. I’m guessing that Jeremy didn’t know his rights in this circumstance and NASCAR took full advantage of that.

  6. Diandra, great explanations!

    I would hate to see any driver taken down by a $10-hour lab technician, who may have labeled the wrong urine sample, and “doctor” who just might have a conflict of interest to maintain his profitable gig with NASCAR.

    Mayfield has a good legal case here, but even if he wins, I doubt he will ever be able to race in NASCAR again.

  7. There are now several reports quoting Dr. Black Monday that he personally told Mayfield exactly what the test disclosed and discussed it with him. It is not entirely clear to me whether a copy of the written report has already been sent to Mayfield or not, but NASCAR stated today that he can have a copy if he wants.

    This is the only place I have seen a reference that “there was a problem with the test….” Everything else I have read is that after the A sample tested positive, Mayfield had the right to and elected to have his B sample also tested and it came back positive also.

    Curiously Mayfield is the 6th person suspended this year from NASCAR, but is the only one on which an issue has been raised by the testee or the media. Also I find it interesting that no one in the NASCAR media mentions the recent suspension of Manny Ramirez by MLB or how the drug testing programs of MLB, the NFL, NBA, or the Olympics operate – and whether Aegis does any of said testing.

    If Mayfield had a problem with the NASCAR drug testing program he should have raised it in February when one of his team members was suspended. It would appear he feels the program is fine, unless it is applied to him.

  8. The general use of ‘A’ and ‘B’ in drug testing is that the same urine sample is used for two different types of tests – the immunoassay (love that word) and the GC-MS. The immunoassay is a cheaper test that is more of a screening test. If something shows up in the A sample, the B sample is tested using a more sophisticated test.
    Knowing NASCAR, they may very well have decided that — just because they can — they will use the same terminology everyone else uses, but use it to mean something else.
    I will reiterate what I said in the blog. This is a really, really serious issue. No one should be out there if they are even marginally impaired; however, if you’re going to suspend someone who doesn’t admit to using a substance that impairs their judgement, you darn well ought to have an iron clad case against them, as you’re dragging their reputation through the mud and that kind of a dirt doesn’t wash off easily. Split the sample into four and send two samples to each of two labs, one chosen by NASCAR and one chosen by the testee. And there shouldn’t be a ‘grey area’ when it comes to drugs. Drivers should have a list of what is and isn’t allowed. They shouldn’t be driving in pain (which is an impairment in itself) because they can’t get an answer about whether it’s OK to take ibuprofen.

  9. Elliott Sadler and other drivers have stated publicly that the drivers were given Dr. Black’s cell phone number early this year so they can call him whenever they have a question about a substance.

    You seem to be using a lot of assumptions, rather than facts, in reaching a conclusion. All the reports I have read have stated that after the A sample failed the test that Mayfield had the option and elected to have the B sample tested, and it failed also. I have read no where that the samples were subject to different types or degrees of testing.

    From what I have read, NASCAR randomly tests 8 to 14 individuals each race week, including at least 4 drivers, and that Aegis is one of the largest, most respected drug testing labs in the country. I have not had a chance to research whether MLB, the NFL, NBA, or the U.S. Olympic Committee regularly has all tests checked by 2 different labs as you suggest should be done. Also, from what I have read even Mayfield is only questioning the accuracy of the tests.

  10. Richard: I haven’t reached any conclusions other than the way NASCAR is handling this could be much improved. In none of the other sports you mentioned do athletes have to call someone to figure out whether a drug will or will not cause them problems with testing. Biffle made the statement that after he had a wreck in the Nwide series, he was unwilling to take anything for the pain because he couldn’t clear it with the medical people.
    NASCAR is unique in that a runner on steroids will harm only himself. A driver whose judgement is impaired can kill people. Likewise, once a driver has been identified as a drug user, the chances of his recovering his career are very small. The cost of using two labs to be positively sure is small compared to letting someone on the track who is impaired, or destroying someone’s career unfairly. I don’t know if Mayfield is guilty or not: There is not enough evidence to make a conclusion; however, it will be really interesting if this goes to court and the details come out.

  11. Hey Marc – good to hear from you and thanks for the good wishes for Charlottesville. I’m looking forward to visiting U. Va. – Haven’t ever been.

    Yeah, sensational headlines are the lazy journalist’s godsend. You don’t actually have to write a news piece, just an opinion piece. I don’t understand why there was such a long delay between testing the A sample and the B sample.

    The folks I’ve talked to about hair testing – not hair folicle testing – believe that the timescale for what you can learn is much longer than a few days. There is definitely some controversy about the method’s sensitivity and it is not sensitive to some drugs that are easily detectable in urine; however, there are some interesting studies showing that long-term alcoholism can be diagnosed via hair. Mayfield’s passing a hair test wouldn’t “prove” him innocent, but failing it would certainly be damning.

    I realize that Aegis is a very well-respected lab and Black a respected doctor, but the scientific literature (and the newspaper) is full of people covering up for honest and not-so-honest mistakes. There are a lot cases of people being let out of jail because a lab tech somewhere messed up records or just wasn’t careful enough. Even being as careful as possible, mistakes do happen. My point is that the stakes are high enough that the procedure should be above reproach. If I were NASCAR, I would want the whole thing to be beyond question. All this BS of “I haven’t been told what it was”/”I told you personally”/”I haven’t gotten it in writing”/”I don’t issue the reports, NASCAR does” just makes everything look suspicious and amateurish. It’s like NASCAR never ID’ing the Waltrip fuel additive from a couple years ago.

    The thing that should happen probably won’t: Mayfield should get the report, make the contents public, identify the prescription drug that he claims interacted with the Claritin-D and then let people evaluate whether that’s even a possibility. Dr. Black doesn’t think so and he may be right, but the number one skill you need to be a scientist is the utter inability to take anyone’s word for anything. Show us the data.

  12. What is NASCAR thinking, the person who runs the testing program, Dr. David Black, owns the laboratory where the testing is done (Aegis); I would not like to go in to court and have to defend that scenario, even if it is completely on the up-and-up, it just doesn’t look good. A quick view of their web site shows they hold several licenses, but there’s no indication that their documentation meets NBS certification.
    My prediction: this is not going to have a happy ending. Some or all of the parties are going to look like fools (at best), or liars (with legal implications).
    The wheels of science fell off this wagon and it crashed into a ditch full of doo-doo.

  13. Diandra – “That’s OK because we have the B sample and if the A sample shows that there might be something there, we then analyze the B sample using a more specific technique.”

    Correct, the problem I’ve seen from the start is how “A” and “B” are taken.

    Simply they should be taken simultaneously and in separately marked and cataloged bottles.

    Reason being (example not related to Mayfield) someone who is “dirty” takes test “A” and then has X number of days before “A” is tested found “dirty” and then a number of days before test”B” is taken.

    That gives the testee enough time to either flush his system “manually” thru various products on the market or the banned substance will naturally leave the body.

    Simply, NASCAR needs to take two smaples at the same time to prevent this from occurring.

    As one who spent 18 of 20 years in the Navy filling urine samples (two at once) I was very surprised they screwed up this simple process.

    In answer to some in this thread test “B” is not optional or at the request of the testee, once “A” is dirty “B” mandatory to confirm the first test.

    As for a banned drug list, yes I agree and it should not only be illegal or other harmful drugs but OTC drugs that can and will pop positive. Hell poppy seeds will pop positive for heroin to give a crazy example.

    That said, crew members have been given a list it’s hard for me to believe drivers wouldn’t have seen it or have their own copies by now that excuse holds little water with me.

    Frankly I don’t see the conflict of interest charge. Aegis is one of the most widely respected labs in the world, Dr. Black being the owner is a non-issue, and I doubt if he’s the sole owner regardless.

    I’ve tried to be even-handed, but frankly his stunt of violating suspension by being on premises at Lowes was not just beyond the pale but flat-out stupid.

    Additionally his refusal to enter rehab is equally ignorant and does zero for his creditability if this case goes to court.

    Finally, Diandra, you note the hair folicle test and Mayfield claims he’s taken one in an effort to prove NASCAR’s tests are wrong.

    Sorry, Mayfield fans (or other interested parties) it’s a RUSE it won’t prove a thing.

    (Quoted from my post: http://fullthrottle.cranialcavity.net/mayfield-speaks-nascar-issues-rebuttal)

    Hair follicle tests can detect a wide-range of drugs for up to 90 days prior to the test and are generally regarded as being ten times more accurate than a urine sample test, although what is tested for and detected may not be what Mayfield is accused of taking.

    Additionally, it’s generally accepted that in order to test positive, the drug in question must have been used 3 times or more within the window of the test.

    That said, the down side of hair follicle tests are their inability to detect very recent drug use (of up to 1.5 weeks).

    Mayfield is pinning his hopes, in fact his entire career given the fact he’s refused rehab, on a test that won’t show negative, positive or even false positive results in the 10-11 days prior to NASCAR’s Richmond test.

    The reality is his test is meaningless regardless of its final results as it won’t cover the time frame in question and may not be capable of detecting the same drug he was accused of taking.

    P.S. Diandra: Good luck with your “NASCAR: The Science Behind the Speed” lecture Thursday at University of Virginia.

    Knock’em dead.

    P.P.S. One thing I’ve been pissed about is how some of the media has headlined some stories.

    “NASCAR let driver on track a 173mph” As if to imply they purposefully placed people in danger.

    Well D’OH Mayfield was innocent until the second test results came back. They had no friggin’ choice.

    Screwy editors. they’re like wives you can’t live with …. oops I better not go there!

  14. Well, given Mayfield, antics now and some in the past I find it hard to believe he hasn’t been told what drug he was positive from.

    It all smells of denial and scrambling for a grasp at a thin and tenuous straw.

    While I agree many people have been wrongly accused based on flawed tests they are a very small percentage as compared to the millions of tests given each year.

    Mayfield has claimed NASCAR’s story has changed, well D’OH so has his. First it was Claritin D for allergies he suffers from and taken in combination with a script written by his doctor.

    The latest version is he suffers from Attention Deficit Disorder and he took something for that.

    So which is it, or is it both?

    There is a simple solution, and the answer sits plainly in Mayfield’s lap.

    He can give written and oral permission to NASCAR and Aegis Labs to release all data on both tests. In addition he permits his personal doctor to release what he suffers from and the drugs he’s been taking.

    Then 95% of the bluster in the media, on blogs and forums would be cut short and put to rest.

    At that point the only remaining question is the validity of the tests given.

    On that point I give him about a 5% chance of winning in a court of law, in the court of public opinion who the hell knows, there’s so much idiocy out there based on “Brain France Derangement Syndrome” rather than an objective look at the facts anything is possible.

  15. Diandra, just heard on Sirius Radio (5:10pm) that the “A” and “B” samples are actually one sample.

    At the time of test “A” that sample is split into two separate test the second one to be used in case the first pops positive for a banned substance.

    At this point I have not been able to verify this, I’ve sent off a couple emails to media members I trust (a short list admittedly) trying to confirm it.

    Maybe you can use some of your “horsepower” to track down the truth.

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