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A surprising reason why some newborns test positive for marijuana

2:48 pm by | 10 Comments

baby, newbornSome newborns are testing positive for marijuana exposure and the reason why could surprise you.

Soap and hand wash products, including products commonly used in hospital nurseries, can interfere with urine drug tests of newborns and lead to false positives, according to a new study from the University of North Carolina at Chapel Hill.

The June issue of Clinical Biochemistry published the study, which was led by Catherine Hammett-Stabler, a professor of pathology and laboratory medicine at UNC Hospitals. Last year, UNC Hospitals increased use of a urine test to identify tetrahydrocannabinol-delta 9-carboxylic acid, or THC, the main chemical component of marijuana. The screening protocol had been revised to be consistent with the latest recommendations for newborn drug screening.

In the study, Hammett-Stabler said that clinical labs received a call in July 2011 from nurses in the newborn nursery asking about an increase in positive THC results from the drug screens. While urine samples tested positive, samples from the first bowel movement were not. Something was causing the positive test results and it wasn’t marijuana use. The mothers’ and newborns’ drug histories showed no potential agents that could alter a screening test.


Hammett-Stabler concluded that something was getting into the samples and interfering with the tests. After eliminating cotton balls, collection containers and possible dyes in the outer portion of diapers, the team focused on baby wash. A test of commercially available baby washes identified some of the chemicals and detergents that were causing the false positives. But the team does not know the mechanism by which these agents are causing the positive results.

“Structurally, these things don’t look like marijuana metabolites, but clearly they are being recognized by the antibodies used in the immunoassay,” Hammett-Stabler said in a statement. “And when testing those reagents in increasing concentrations we did see a positive response, aleit really low, just over the point of positive.”

Dr. Carl Seashore, associate professor of pediatrics at UNC and a co-author of the study, said the findings underscore the need to confirm positive marijuana test results with more sophisticated methods before child social services are contacted for what may be a false allegation.

“We wrote this paper to inform care providers and laboratory medicine people in hospitals that this issue is out there and that positive urine screens for THC need to be confirmed,” he said.

[Photo from stock.xchng user kodakgold]

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By Frank Vinluan

Frank Vinluan is the North Carolina Bureau Chief for MedCity News.
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People really misunderstand the nature of drug tests. They DO NOT, EVER test for a drug. They test for chemicals that are often so common they show up in thousands of other things.  Tests for opiates will get false positives on poppy seeds, for example.  We should be wary of using drug testing, or any test, as some kind of magical detector of illegal or immoral activity.  I walked through two clouds of MJ smoke on my morning commute downtown within ten blocks of the police station in the last week.  Something like 90% of all money tests positive for cocaine residue.  Does that mean 90% of people are snorting coke through rolled up money?  Or even 9%?

Addiction Professional
Addiction Professional like.author.displayName 1 Like


 Your poppy thing is simply inaccurate.  It would take a huge amount of consumption of poppy seeds to get the false positive for optiates, highly unlikely.  Addicts in treatment have exhausted that excuse beyond belief.  You are correct about the false positive issue being a problem, but it is rarely a big issue in addiction treatment.  It is huge here, since this is a population with little basis to expect drug use.


JAMA reported years ago that there were small children testing positive for cannabis.  It was traced to second hand smoke.  This becomes a potential medical issue for the child, and is a big issue for Child Protective Services, as the exposure is rightfully recognized as a form of abuse.

Benjamin like.author.displayName 1 Like



"It would take a huge amount of consumption of poppy seeds to get the false positive for optiates, highly unlikely."


Absolutely false.  See "http://www.snopes.com/medical/drugs/poppyseed.asp" for example.  Many community programs for addicts include an agreement to not consume poppy seeds at all because this is such a problem.  But it has still been an issue in random drug tests at work places (work places rarely tell their employees to abstain from poppy seeds due to random drug testing).

Dr Z
Dr Z

This is not a REPUBLICAN agenda, babies are tested if there is a concern for the health and safety of the infant.  Drug use is still illegal and can be dangerous to the baby. Doctors need to do right by their patient - in this case the baby - and do everything in their power to ensure the safety of the baby.


Oh really,like the idiots in P.A,who wrongfully took 2 newborn babies from there mother over poppyseeds muffins! Isnt ,''bonding''  important as soon as baby enters this world??The truth is these so-called,''drug testing  kits'',  are actually ,''compound making kits''...The chemicals used in these compound making kits are the same chemicals used in illicit drug making,thus creating a postive result everytime if anyone ate a poppyseed  muffin,coca tea,sudefed,vicks inhaler,the list goes on.All of chemistry is a recipe.W/out these ,''drug reagants'' there would be no positives results when folks enjoy a muffin and a cup of tea at breakfest.Example of drug reagants recipe is,'' coca tea+ethanol+hydrochloric acid=benzoylecgonine,the governments ,''new''  definition of cocaine,even though its not cocaine.Anotherwards no ethanol or hydrochloric acid,no benzoylecgonine.Ethanol/hydrochloric acid are the so-called ,''drug reagant'' used in all cocaine,but really benzoylecgonine making kits used against all people in the U.S.A. subject to forced so call drug testing,even though they never ever really test anyone for drugs!!!!Corrupt,,all of it is corrupt!!.paita  


So legal drugs must be okay then.


Wasn't this idea of drug testing Moms born of the Republican notion of less government in people's lives?


When a woman gives birth her body releases our body's endo-cannabinoids because of the high stress situation. They can be mistaken for the phyto-cannabinoids present in cannabis. Runners body's release the same thing. It is a good thing that protects our body's. :)