Prior to this year, plenty of marijuana sold in California dispensaries received intense scrutiny from testing laboratories searching for evidence of pesticides and other potential hazards.

But the tests were voluntary. Growers and brands paid for the tests to publicly demonstrate transparency about issues that matter to consumers.

Meanwhile, cannabis made it to jars on dispensary shelves and into concentrates and edibles without any oversight — and with more pesticides and other ingredients than most consumers would likely accept.

As of January 1 of this year, however, all marijuana sold in California must be tested under state law. And the tests are rigorous — some of the most stringent in the United States.

The regulations, drafted by California’s Bureau of Cannabis Control (BCC), require that all batches of cannabis products undergo testing by third-party laboratories that interrogate the samples for safety and dosing accuracy. Some of the requirements went into place on January 1, but during the course of 2018 more rules will be phased in at different times — Phase II begins on July 1, and Phase III on December 31. By 2019, California cannabis will be on the receiving end of an extensive testing regime.

California cannabis undergoes extensive testing for pesticides and other contaminants

Caliva’s cannabis undergoes extensive testing for pesticides and other contaminants.

The testing falls into a handful of broad categories, including potency, pesticides, microbiology, terpenes, heavy metals and more. The point? To protect consumers. Compliance, however, will not come cheap. Last year, the BCC analyzed the potential costs associated with the anticipated mandated testing and concluded it would add an average of $407 per pound. The report said, “This will affect cultivators, manufacturers, and distributors who will be paying for the required testing.”

In many cases, it will force state-licensed testing labs to invest in pricey new equipment, costs that likely will end up hiking the fees cannabis companies pay to get their products into sales channels.

Either way, the new regime is here, and during the course of 2018 the regulations will grow increasingly more stringent and sweeping.

Bureau of Cannabis Control – Required Testing Chart

The following chart, created by the Bureau of Cannabis Control, outlines the requirements for cannabis testing.

This chart is a handy timeline for cannabis testing regulations.

Marijuana Testing 101


The rules for potency are fairly straightforward. Tests for all products, including flower, edibles and concentrates, must demonstrate potency levels within 10 percent of the stated label claim.


Pesticides are widely used in most agriculture — even organic agriculture leverages pesticides, only they are all-natural rather than something hatched in a Missouri laboratory. Pests adore cannabis, and growers for generations have used a wide variety of chemicals to protect their crop.

And now, those crops are getting tested for 21 different kinds of pesticides. Interestingly, until the rules change again during the summer, the state does not articulate how much of a given pesticide is too much — they leave that up to the individual testing labs. But when the state embraces Phase II of the testing regulations, on July 1, the number of tested pesticides rises to 66 and labs must all follow tolerance guidelines for pesticide content in products. The tolerances are sometimes extremely low, and testing for them requires the use of pricey technology: an LC-MS/MS (liquid chromatography tandem mass spectrometer) and GC-MS/MS (gas chromatography tandem mass spectrometer).

Equipment like this is far more advanced than much of the technology used to test for pesticides in the past. The requirement will force labs to invest in more expensive equipment, which will likely add costs to producers (and of course in the end, consumers), but it does achieve state-wide standardization.


These are pass-fail tests. If the product exhibits the pathogen, it fails. Otherwise, it gets the green light.

The tests include ones for shiga toxin producing escherichia coli, which is related to e. coli and salmonella. For flower and concentrates — products that get inhaled — tests for aflatoxins are introduced. Aflatoxins come from molds, and are carcinogenic.

Residual Solvents

Phase 1 (effective now) tests for 6 residual solvents in concentrated forms of cannabis, such as shatter and wax, and none of them are widely used in cannabis production. The Phase II requirements add 14 solvents to the list. For all of the solvents, the state mandates tolerance levels.


The state doesn’t care whether a product contains terpenes or not, unless products broadcast terpene presence. If so, the state steps in and tests the products to ensure the terpenes being advertised do in fact dwell within the product. State-mandated terpene testing will not be implemented until December.

Heavy Metals

Cannabis plants are so good at removing heavy metals from soil that they have actually been used to do just that. This is excellent news for the soil, but it gives regulators pause — if cannabis is so great at accumulating heavy metals from soil, what does that mean to the consumer who is inhaling, ingesting or applying cannabis? Are the four primary heavy metals — arsenic, cadmium, lead and mercury — entering their bodies in dangerous amounts? The jury remains out about whether heavy metals accumulate in flower in amounts that pose any threat to consumers — some evidence suggests it is possible. Either way, once Phase III regulations spring to life, state-licensed laboratories will test for the four heavy metals.

Moisture and Water Activity

What’s wrong with water? It’s not the H20 with which the state takes issue — it is the pathogenic activity that water supports that worries regulators. Testing of moisture is measured simply as a total percentage of water in a product. The limit is 13 percent. Water activity, testing for which begins during Phase III, is a bit more complicated, and probably the better barometer of connections between water and microbial growth because instead of just measuring water content, it measures the amount of available water. The science and math behind this testing is not intuitive, as it is for water content. In sum, the acronym “Aw” stands for “water activity” and the tolerance level for Aw in cannabis products is 0.65 Aw.


These byproducts of fungi are toxic, and are extremely common on cannabis plants. The most common and dangerous mycotoxins are subject to testing: Aflatoxins B1, B2, G1 and G2; and Ochratoxin A. These are not pass-fail tests for mere presence of the mycotoxins, but tests where amounts above certain state-mandated tolerance levels count as fails. All of them will have tolerance levels of 20 micrograms/kilogram once Phase III regulations are implemented in December.


This rule applies only to edibles companies, and it requires them to submit to 10 tests for THC or CBD of 10 separately packaged products, for the sake of establishing the homogeneity of their products. In other words, they need to prove that within a box of gummies, a chocolate bar divided into servings or any other edible product that contains more than one serving the potency is homogeneous. And that that homogeneity extends beyond the one package — that all tested packages contain proper doses.

The average potency of the servings within the product must be within 10 percent of what the company is saying about potency levels, and the standard deviation of all samples must be less than 10 percent.

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