Joint by Torben Hansen
[Image courtesy of Flickr user Torben Hansen via a Creative Commons license] If you enjoy one of these and have a job at a company that conducts drug testing, you need to know what these tests detect and how it affects your use or marijuana and ability to keep a job.
Drug-testing day is never a favorite day for any worker who smokes marijuana, even in states where smoking it recreationally is permitted.

If you are a worker, there is a chance that you may be subject to a pre-employment drug screening or a random drug test while employed. And while you never smoke marijuana on the job or just before a shift, you may still tend to worry about whether that joint you smoked last night is still in your system.

If you are wondering, you have good reason. Let’s take a deeper look into how long marijuana (or more specifically, THC) can remain in your system and how it is detected.

So How Long, Exactly?

To be honest, there is no exact answer. The best answer to the question is, it depends.

Similar to alcohol, the amount of time it takes for marijuana to leave your system to avoid detection by most tests is based on your body size, metabolism rate, amount and frequency of use, among others.

However, our friends at LeafScience created his chart to show at least a ballpark expectation based on the amount you smoke:

how-thc-system-chart courtesy of LeafScience

As you can see, even if you are an occasional user of marijuana, chances are good that if you smoked weed last night, you will likely fail a drug test at work this morning. In fact, you will have to be even more occasional as a user, because most research seems to show that your body will generally need 3-4 days to get below a drug-test detection threshold.

And if you are a heavy user, then maybe quitting would be a good option, because it will take you at least two months to be able to pass a drug test. And who has that kind of time?

What is Detected, Exactly?

THC is the substance in marijuana that causes the “high” that creates impairment. But as the liver metabolizes alcohol, it also does the same to THC and it creates a metabolite chemical called THC-COOH. This metabolite is the chemical that most tests are detecting. This, if nothing else, at least indicates that a person has used marijuana recently. It does not necessarily determine whether a person is currently using.

There are several tests and they all have their own thresholds for detection, but the baseline standard for many tests is to find a concentration of THC-COOH equivalent to 50 nanograms per milliliter (called ng/mL). some can be as stringent as 20 ng/mL and others can be as lenient as 100 ng/mL. As we write about detection here, we will refer to the 50 ng/mL standard as it is most common.

How Can THC-COOH Be Detected?

The most common test for THC-COOH is most workplaces is through a urine test. There are other tests that could be used that have different detection schedules, but they are not used as much because of privacy concerns.

Hair-follicle, blood and saliva tests may also be used to detect the presence of THC-COOH in the body, but usually those tests are only administered in situations where it is believed that a person may be “high” while on the job.

The difficulty with blood or hair tests is that they tend to register the presence of THC more immediately than a urine test.

As urine is the most common way that the body gets rid of toxins and waste, it is the mot prevalent way to detect the presence of THC or THC-COOH in your system, and thus the easiest way to determine if you are or have been a marijuana user.

On What Does Detection Depend?

Obviously, detection depends on the threshold in which the test is designed to test, but there are other factors that go into an individual’s ability to pass THC-COOH out of the system in a certain amount of time.

As THC and its metabolite tend to “live” in fat cells, those who are overweight will take longer to clean their systems than a skinny or average person with the same level of marijuana use. Those who are moderate or heavy drinkers – which already tax their livers, thus reducing the effectiveness of the liver to break down THC – will also struggle with passing a marijuana test, as will those who don’t drink much liquid in the first place (non-alcoholic liquids, of course). A person’s rate of metabolism will vary as well – those with high metabolism rates will flush out the THC and its metabolite more quickly than someone with a slower metabolism.

What are the Detection Periods for Each Test?

It really is important to understand the type of test that will be administered to you, as each type has varying time of detecting either THC or THC-COOH in the system. There is a reference table here that can help explain a little better what you are dealing with in terms of when you need to stop using marijuana so that you can pass the test.

In short, the urine test is the most sensitive test, as THC-COOH can remain in the body much longer after ingestion of THC than THC does itself (which is usually what is detected in blood, hair and saliva tests). While urine may not indicate current use of marijuana, a blood, hair or saliva test is more accurate in determining whether a person has very recently or is currently using marijuana since they check for THC which may be in the system before it has reached the liver to be broken down into the THC-COOH metabolite.

If you use marijuana once, a urine test can give a positive result for THC-COOH as much as a week after use, while a blood test can read for up to 24 hours, as an example. If you are a regular marijuana user, you may have to wait as much as 90–100 days to pass a urine test, based on the level of use and your body mass and metabolism. A blood test can find active THC in a regular user for up to a week after last use, while a hair test may read THC for months.

How Might I Speed Up the Detox Process?

The best ways to detox your system of THC-COOH in the quickest way possible in order to pass a urine test are not very scientific or expensive. In other words, beware of those products hat claim to be able to detox your body quickly or offer you a “clean” urine sample. Drug analysis labs nowadays are not that stupid and they are very good at noting faulty samples or samples that have been changed or tampered with, so it is never a good idea to shell out a bunch of money for these gimmicks.

Instead here are a couple of simple, low-tech ways to help speed up the detox process.

First, quit smoking marijuana altogether. Your body will heal itself over time.

If you are not quite ready for that, you could drink water or some diuretic liquid such as cranberry juice or coffee. However, be careful about water. You might have to drink a lot of it in order to get marijuana out of your system, and if you dilute your urine so much that is doesn’t look yellow anymore, that could send up a red flag at the lab that you might be “cloaking” the drug. Cranberry juice seems to be more effective, and you could alternate that with water to create a more “natural” look to your urine.

Some other tips include not using your first urination of the day as a sample, and do not use the first couple seconds of your urine stream, as that contains the greatest concentration of metabolites.

But if you have to go through all this in order to pass a test, maybe you can do this just the one time, and then be rid of marijuana use altogether so you don’t have to stand on your head in order to keep a job.


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