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The Many Excuses for Positive Drug Tests

Woman snorting cocaine at party

We acknowledge that the on-site drug testing process, using immunologically-based methods, may have some potential for ‘false positive’. These results are attributable to cross-reactions with medications, foods or other substances that may be present. However, we are extremely confident that the laboratory confirmation procedures, using chromatographic anlysis with mass spectrometric detection and quantitation, is highly selective, specific and above all accurate.

This does not prevent some drug test subjects from making a wide range of claims that there is an explanation for their positive result.

A recent news report described a nurse who tested positive for cocaine in a urine drug test and claimed that she had previously had ‘sex with a sweaty guy’ without a condom, whose semen allegedly contained cocaine. Her decision not to shower nor to use the toilet prior to her drug test caused her to either (a) absorb sufficient cocaine from skin to skin contact that she absorbed cocaine from his sweat, or (b) the residual semen contaminated her urine specimen.

The expert reviewer’s response was particularly blunt:

to see such a result would be unlikely from sweat and that half a litre of semen would have to be present to yield so much cocaine.

Similar claims are made for those testing positive for cannabis, including;

  • “I kissed my girlfriend after she smoked a joint”,
  • “I ate some muffins/cookies that must have contained cannabis”,
  • “I take supplements from the health food store and it isn’t listed in the ingredients”,
  • “I got it in Canada and it is legal there”, and
  • “Impossible! I bought some stuff on line that was guaranteed to make me pass the test”.

The old favourite “I was in a car/room with others smoking cannabis, so I was passively exposed” doesn’t really stack up. Research data have shown that to test non-negative with an on-site test your friends would have to be Cheech and Chong. To achieve levels exceeding Australian Standards, the subject would definitely have experienced a euphoric high, similar to active smoking. People making this claim knew, or should have known, that they were being exposed.

“I have to light my wife’s joints for her because she uses medical marijuana and she is too sick to do it herself” is an admission of sorts, as well as “my wife is sick and I rub cannabis oil into her skin”.

Cocaine is interesting too. One famous celebrity claimed that, yes, he had used the drug, but only to teach his wife a lesson. “I told her that for every line of cocaine she took, I would take two, and that’s exactly what I did.” Years later, he admitted he had a bad cocaine habit.

Again, unwitting intake of cocaine is a standard excuse,

  • ”I was asleep, and my boyfriend blew it up my nose”’
  • “The 2 gay men that live next to me put cocaine in their air vents, and it must have got into my apartment”’
  • “someone must have laced my cigarettes with cocaine to try to get me addicted”’
  • “well, of course my wife is positive for cocaine, you have no idea how many cokes she drinks everyday”.

Hair samples are washed prior to drug analysis so that environmental contamination may not contribute to the results. However, some data suggest that the washing may actually wash external drug INTO hair, but this is usually excluded from the quality assurance procedures in accredited laboratories. This suggests some interesting excuses though;

  • ‘there must be drugs in the shampoo I use”,
  • “I had a hair transplant and the hair donor must have used drugs”’

Tests for performance-enhancing drugs in athletes give us some complex fabrications. A baseball player tested positive in 2012, was suspended for 50 games, He paid an associate $10,000 to create a fake website selling fake products, then claimed he accidentally ingested performance-enhancing drugs via a fictional product obtained on the website FBI traced the website back to him so he was caught out.

Another athlete tested positive for high levels of testosterone in 1998. His defence was that “his maleness was up” because he had five beers and had sex with his wife five times the night before. “It was her birthday. The lady deserved a treat,”

Foods can contain the opiates morphine and codeine, especially poppy seeds, and Australian poppy seeds are particularly rich in these substances. One donor, positive for codeine and morphine sent me a photograph of her pantry showing how many poppy seed products she used!

Of course, there are the old standards;

  • “There must have been a mix-up with the samples!’, or
  • The hair sample must have been analysed the wrong way around. I stopped using drugs months ago”.

But my favourite of all time?

I thought we were going to do the drug test next week.


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