If you’ve received a positive hair follicle drug test result, or you’re just concerned because you have so much riding on the outcome of the test (job, your freedom, etc), there’s a pretty good chance that you’ve thought to yourself, “Is it possible a drug test can be wrong?”

First off, let’s just be upfront and say that the hair follicle drug tests themselves are not prone to error. There are various procedures that are followed and the labs are simply testing for the presence of certain chemicals using a well-established procedure under highly controlled conditions.

So, when we look at whether or not a hair follicle drug test can be wrong, we are most often looking at factors outside of the testing process itself.

This is a difficult area because the drug testing labs are, for obvious reasons, adamant about the certainty of their results, even if evidence does seem to suggest that we should at least look a little closer at the question.

Drug testing is a big business. And the drug testing industry has been selling corporations and governments on their accuracy for many years now. If they have to backtrack on any of their claims, that would open them up to not only losing business but potentially lawsuits.

It’s sort of like when tobacco companies first began to realize that cigarettes were really bad for people. They’ve been selling these products for decades, some for over a hundred years. Admitting any harmful consequences of using their products would lead to a tidal wave of lawsuits and possibly the outright ban of their product. So, rather than being open to looking at the science, they dig in and defend themselves.

That’s not to say that there is any evidence that drug testing companies have or are doing anything unethical, but it just seems wise to look at how they’re motivated. If a flaw was found in the accuracy of hair follicle drug testing, chances are, you won’t be hearing about it from a drug testing company first. It will likely be researchers outside of the industry and they’ll likely be initially dismissed by the drug testing industry as this information can hurt their business.

All of that is to say that as we explore some of the ways that a hair follicle drug test can be wrong, keep in mind that the drug testing industry typically either dismisses these factors. In other words, if you fail a drug test due to one of these factors, it’s not going to be easy to fight the results.

How A Drug Test Can Be Wrong

First off, an error can occur during the collection or handling of the hair sample. As far as we’re aware, this type of error is rare. Samples are usually collected from trained technicians and specific procedures are followed which are designed to minimize this risk, but it’s not impossible.

Similarly, someone could alter test results once they are stored in a database. One leading drug testing lab announced that they may have been subject to a security breach. Again, what are the odds someone goes in and gives you a positive result on your drug test? Probably not very high. In most cases, hackers are simply looking to steal your data, not alter it.

Unfortunately, both of the above would be a hard one to prove even if they occurred.

But, let’s look at whether or not the test itself can be inaccurate.

Second Hand Exposure

There is some debate whether second hand exposure to drugs can cause a positive test result. The drug testing industry says that a false positive result is impossible. Yet, there have been more than a few cases where someone with impeccable credibility has claimed they have never ingested drugs yet still tested positive.

As an example, the Massachusetts Appeals Court recently ruled that six police officers that had tested positive for drugs be reinstated as, absent any other evidence of use, the court deemed the hair follicle test too unreliable.

The officers involved in that case insisted that their constant exposure to drugs in their day-to-day duties, potentially caused a false positive test result.

In another case involving a police officer, she claimed that her hair extensions may have contaminated her actual hair sample. In this particular case, the officer tested negative for a urine test she took the same day as the hair test and she paid to have another hair test done which also came back negative.

Potential Racial Bias

It’s actually somewhat sad that the drug testing industry insists that their tests have no racial bias when basic common sense would indicate otherwise.

The simple fact is that drug metabolites bind with melanin in one’s hair. People with dark hair have more melanin than people with light hair. It doesn’t seem to take a rocket scientist to figure out the logic on this.

Of course, this doesn’t make the results wrong, it just means that the test has some racial bias built into it. The drugs got into the hair. It’s just a matter if as many natural blondes get caught as often as do African Americans or Asians.

What is 90 Days?

One of the big selling points of the hair follicle drug test is that it can look back at your last 90 days of drug use. But, the drug testing labs know this is a misleading claim. It’s approximate. My hair and your hair don’t necessarily grow at the same exact rate. The drug testing labs use research which indicates that hair grows, on average, 0.5 inches per month. But if my hair grows faster than average, the sample I supply will have less than 90 days worth of growth. If your hair grows slower than average, that same 1.5 inch sample may represent 100 or 110 days of growth.

Similarly, body hair does not grow at the same 0.5 inches per month but if you are bald or you shave your head, the lab will take a sample from your chest, underarms, or other parts of your body in order to obtain a 1.5 inch sample.

But similar to the potential racial bias, you might be hard pressed to find a sympathetic ear given that the drug usage is not in question, only the accuracy of the result being called into question. Most of the people ordering a hair follicle drug test aren’t concerned about the racial fairness of the test or whether you smoked weed 100 days ago vs 90 days ago.