How Does A Marijuana Blood Test Work?

marijuana blood test

As more states legalize medical and recreational marijuana use, employers and law enforcement agencies are using a variety of drug detection methods to identify recent marijuana use. Whether you're starting a new job or at the scene of a car accident, you may be subjected to a host of drug tests to detect illicit substances in your system. A marijuana blood test can detect marijuana use, but is uncommon due to its invasiveness and high cost. To determine marijuana intoxication, many states are adopting a per se limits of 5 nanograms per milliliter of Delta-9 THC (THC) in the bloodstream. These cutoff limits on THC concentration in the blood aim to improve safety, but research shows that the arbitrary limits are unreliable markers for impairment or intoxication.

How Long Does THC Stay In Your Bloodstream?

After smoking or vaporizing cannabis flower or concentrates, psychoactive THC enters the bloodstream through the lungs. Immediately after smoking, users report feeling euphoric and blissful due to a high concentration of THC interacting with cannabinoid receptors throughout the body. Depending on frequency of use, metabolism, and potency of a cannabis product, the effects can last for at least a couple of hours. When smoked, THC levels in blood will drop quickly within the first couple of hours. Vaporizing cannabis can increase the concentration of THC in the blood compared to smoking it.

When you consume a cannabis-infused edible, however, THC is metabolized in the liver before it reaches the bloodstream. This delayed metabolization process reduces the amount of THC that gets into the bloodstream. During metabolization, THC gets broken down into its metabolite byproducts, Since THC and its metabolites are fat-soluble, THC binds to fat cells in your body. THC metabolites will remain in your fatty tissue until your body needs them for energy. It can take a long time for your body to tap into its fat reserves leaving THC longer in your system. THC can be detected in your blood after a few hours to days after use, if you're a heavy smoker.

How Does A Marijuana Blood Test Work?

Marijuana use can be detected through a variety of tests using urine, blood, hair, and saliva samples. Urine is the most commonly used drug test due to its efficacy and affordability. A urine test, however, does not measure impairment. A marijuana blood test works better to determine cases of recent use since THC blood levels peak just minutes after inhalation. Blood tests detect THC and also metabolites like THC-COOH and 11-hydroxy-THC. While a marijuana blood test can detect marijuana use, it's not very common since it can be invasive, expensive, and time-consuming.

A marijuana blood test can detect a wide range of illegal substances to determine intoxication. Marijuana blood tests have a short detection time making it ideal to determine impairment at the scene of a car accident or after an injury. During roadside screenings or a crash, drug recognition experts will determine intoxication through a series of physical and mental exercises. If a police officer believes you are under the influence, you can be asked to submit to a blood test at the police station or a medical facility.

Typically, a marijuana blood test has a 12-24 hour detection time for occasional smokers or 7 days for heavy users. A marijuana blood test does not determine the method of consumption. You may refuse to submit to a marijuana blood test, but will get your license revoked for at least a year and suffer harsh penalties.

Is a Marijuana Blood Test Reliable?

Despite all of the innovations in cannabis drug testing, there is still no reliable method to determine cannabis impairment. Federal laws make it nearly impossible to research how much cannabis leads to intoxication. The lack of consensus has meant states have been unable to determine a standardized limit across the board. Unlike alcohol that can easily be found in your blood, THC can remain in your body long after consumption, especially for heavy users. Current cutoff levels for THC in blood can't scientifically determine impairment or intoxication.

One study found that THC can be found up to a month after abstinence for daily cannabis smokers. Some participants had THC levels of 5ng/ml days after they had stopped smoking cannabis for a few days. Another study found that occasional smokers could smoke a joint and test negative for marijuana right after. Another blow to the traditional marijuana blood test came in the form as a study conducted by the AAA Foundation for Traffic Safety. The study found that it takes an average of 165 minutes before a blood test is conducted on someone suspected of intoxication. This means that first-time cannabis users can avoid detection since THC levels drop dramatically within the first few hours.

As more states seek cannabis legalization, expect to see an uptick in drug screenings and technology. The science behind marijuana drug testing has enabled tests to detect the smallest amount of cannabinoids in the body. The problem lies in interpreting those results to determine a reliable THC level. Studies are linking cannabis legalization to an increase in drivers that test positive for THC. Many states have adopted low cutoff levels or a zero tolerance policy toward marijuana, altogether.