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Baby Boomers who smoked marijuana in the sixties are, today, not getting diagnosed with Alzheimers at the rate they should be.

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How To Read Lab Test Results

How To Read Lab Test Results

Most of the marijuana on the black market is full of mold. And some heavy duty pesticides, bugs and bacteria, too. Legal marijuana has the same problem - dirty, unhealthy weed. Which means that the lab test results are the most important numbers on the label of your marijuana products. Lab testing tells us how potent the marijuana is and whether it is safe to consume. Never, ever consume marijuana that hasn't been lab tested for pesticides, mold, residual solvents and other contaminants. 

Dispensary cannabis flower and other medicines are lab tested to make sure they are safe for people to use, especially people with compromised immune systems. To be safe, cannabis must be free of pesticides, mold and other contaminants. Lab testing for marijuana is different in every state. Some states require hundreds of dollars worth of testing for each batch of marijuana flower. Other states don't require any testing at all. If you live in a state with lax testing regulations, you are going to have to be your own quality control inspector. Recently, 80% of the marijuana from a conference in California tested positive for mold and other contaminants. 


Potency testing tells us how much THCA, CBDA, THC, CBD, CBC, CBN, THCV, CBG and CBDV are in marijuana. THC and CBD can be anywhere from 1-30%, but CBC, CBN, CBG and THCV are usually between 0.01-5%. At the dispensary, look for strains with a little bit of all of the cannabinoids, not just THC. 

Flower Results

Marijuana flower potency tests are expressed in percentages. One gram of marijuana flower is 1,000 milligrams. So if a marijuana strain like Harlequin has 10% THC and 10% CBD, it means that Harlequin has 100 mg of THC and 100 mg of CBD in each gram of flower. 

When THCA converts to THC, the numbers change. The official formula is THC total = (%THCA) x 0.877 + (%THC). For quick estimates, look at the THCA percentage on the label. Reduce it by 12%. So 20% THCA reduces to 17.6% THC. It's not a big difference, so a high THCA strain will still be a high THC strain. To get the total THC, reduce THCA by 12% then add that number to the THC number. Do the same for CBD and CBDA. 

Concentrate Results

Concentrates like wax and shatter are much more potent than flower, usually between 50-90%. Just like flower, a gram of concentrate has 1,000 milligrams, so if a concentrate is 80% THC, it means a gram of that concentrate has 800 milligrams of THC. One gram of marijuana concentrate is equivalent to 500-900 mg, so it would take 3.5-6 grams of marijuana flower (15% THC) to equal one gram of concentrate. 

Edible and Topical Results

Edibles and topicals count potency in milligrams. The label will say how many milligrams of THC and other cannabinoids are in the edible. Remember to start low, 10 milligrams at the most, and go slow. For severe pain, some patients do doses as high as 100 milligrams of THC, but most pain and other conditions can be treated with smaller doses, usually between 5-50 milligrams. 

Topicals usually have around 100 mg of THC, but look for pain creams and skin treatments with THCA, CBD and CBDA. These other cannabinoids are just as effective, if not more, for topical applications. 

Terpenes Results

Terpenes are just as important as cannabinoids when it comes to cannabis medicine, and the lab results will list the amount of each terpene they find. In flower, terpenes can be anywhere from 1-15% of the total weight. Concentrates tend to have fewer terpenes because most extraction processes destroy most of the delicate terpenes in cannabis flower. If you want a terpene-rich concentrate, look for bubble hash, kief or dry sift. These solvent less concentrates preserve and protect the terpenes. I love bubble hash for this exact reason - the crazy high number of terpenes. 

Terpenes are usually measured in percentages, but sometimes the results might be in ug/g, or microgram/gram. If the test results list 1000 ug/g, it means that terpene is 0.1%. Simply move the decimal place to the left, 4 spots, to get the percentage. 

In 2017, we don't know a lot about what varying amounts of terpenes in marijuana does to the medicine. We know what each terpene does individually, but we need years of medical research to learn more about how terpenes and cannabinoids work together, and what the ideal ratios are for each condition or disease that we treat with cannabis. Our grandchildren will shake their heads at how uninformed we were, but we're doing the best we can with what we know now. When we know better, we'll do better. 




If your state has lab testing regulations, any marijuana that failed its testing will not make it to the shelf of the dispensary. But if your state does not require lab testing, you need to find a dispensary that stocks lab tested medicine. It will cost more, and it will be worth it. 

Where there are plants there are pests and disease, and some marijuana producers use powerful, toxic pesticides to treat spider mites, mold and other problems in their gardens and greenhouses. If these pesticides are still on the plants at harvest, the medicine made from the plants - flowers, concentrates and edibles - will be chock full of chemical pesticides. One of the tests the lab performs is to make sure there are no harmful pesticides in the medicine. 

When marijuana plants are harvested, they are full of moisture. The flowers are removed from the plant before they are dried and cured to prepare them for smoking. If they are not dried properly, mold will develop in the flowers. Smoking or eating those moldy flowers can cause serious health risksBacteria and fungus can also be harmful for patients

In Illinois, we complain about the costs of lab testing and having to pay for tests of E. coli and salmonella. How would we even get salmonella into the weed? But then another Illinois cultivator did test positive for E. coli. Their "organic" plant food had poultry in it, which infected every plant in their garden. We don't complain about lab testing costs anymore. 

Check to make sure your marijuana medicine is tested for mycotoxins like aflatoxin and ochratoxin. Mycotoxins are just as dangerous, or more, than mold and bacteria. 

And finally, check to make sure your cannabis concentrate or infused medicine doesn't have any residual solvents. When cannabis oil is extracted from the plant matter, solvents like butane are used to strip the medicinal compounds from the plant. These solvents then need to be "purged" from the oil so we don't consume the butane. 

If you live in a state with no testing requirements for medical marijuana, buy co2 oil or edibles infused with co2 oil. The co2 machine strips mold and bacteria from the cannabis oil and does not have any residual solvents. It is the cleanest, safest process for making marijuana concentrates, and your best bet with untested medicine. 

Now. Having said all of that, lab testing is notoriously inaccurate. 

If we pick the top cola, the highest flower that grew closest to the lights, we'll get a super high potency number. If we pick a smaller flower bud from halfway down the plant, we'll get a lower potency result. That's why the same strain of Blue Dream can be 15% THC one time and 20% THC the next. 

And if we give two labs the same marijuana flower, we will get two different potency test results. The dryness of the flower can affect the test results, too. Marijuana testing labs are a relatively new concept, and industry standards have not yet been developed for testing

Don't get too caught up in the potency numbers. Think of them more as a range, rather than an exact number. One batch of Sour Diesel wax will get different test results than the next batch of Sour Diesel wax, even though they were made from the exact same plant matter with the exact same process. If you want the same 1:1 you got last time, but now it says 10/12% THC/CBD instead of 9/11% THC/CBD, it's still the same medicine, it just tested slightly different this time. 


If this all sounds really confusing, just remember two things. Contaminants and Potency. Ask your budtender to only show you medicine that has been tested for both. 


If you have any questions about test results, leave them in the comments. 

Happy Medicating!


How to Make Your Own Edibles with Wax and Shatter

How to Make Your Own Edibles with Wax and Shatter