It has been part of industry and government policies in the U.S. to require future and current employees to be tested for drugs, particularly those with high-risk jobs. Urinalysis is among the most common methods to detect the presence of substances in the body, including marijuana. 

Many state governments have been adopting laws to legalize both the medical and recreational use of cannabis, but some areas still consider non-medical use of the substance illegal. This makes it important to know when, how and where to take marijuana, specially when moving out of the hometown to take another career. 

A 2005 study showed that cannabis could be detected through urinalysis 30 days after the last use. However, a researcher noted such situation is rare.

The frequency of use could contribute to the time marijuana would stay in the body. The study found that occasional users retain detectable traces for only three to four days, while chronic users had an average of 21 detectable days. 

But an earlier research suggested that just 28 days of gap between last marijuana use and the urine test could clear the body from cannabis. The findings come from an analysis of how long cannabis traces remained in people who claimed to smoke marijuana 5,000 times or more throughout their life. 

What keeps marijuana in the body

The body breaks down and absorbs cannabinoids through metabolism. But there are factors that affect how long the drug stays in the body. 

“Each of us has a unique metabolism that processes cannabis at a different rate,” Joseph Rosado, a medical consultant at International Cannabis Solutions, was quoted by Tonic.

He added that age, gender and individual lifestyle choices could also contribute to the presence of cannabis in the system. Rosado said the levels of exercise and eating habits “may affect the amount of time required to pass a drug test.”

Body fat could also keep the drug longer in the body. Fat cells tend to absorb traces of cannabis, making those people with higher levels of fat or those who are overweight store cannabinoids longer than leaner individuals, Rosado said.