This is the fifth article in series of articles on the differences between outdoor versus indoor grown cannabis. In this article, we discuss pesticides.

Pesticide Hazards

Spraying Pesticides

One need only take a minute looking at our CBD Resources page to realize that pesticide misuse is a very real concern when it comes to cannabis. This is even more so the case when it comes to smoking and vaping. The fact that up to 70 percent of pesticides on cannabis will be transferred in the smoke to the lungs and into the bloodstream should give a person a moment for pause.

Thankfully, some states require testing for pesticides like Bifenazate. While it’s tempting for growers to use Bifenazate to kill plant damaging mites, it causes rats to urinate less and have an enlarged spleens. Clearly, failing products that test positive Bifenazate makes sense.

So it’s a good idea to check that your cannabis has been tested for pesticides. However, pesticide testing has serious limitations. Take for example the pesticide Bacillus Thuringiensis. This pesticide is produced by fermenting naturally occurring bacteria found in the soil. This sounds safe enough. The pesticide is OMRI certified organic for use food crops, oral ingestion, and is on California’s list of allowed cannabis pesticides. Nonetheless, the fact is that there is no data regarding the safety of inhaling these microbial-based controls. This is why we hardly ever use pesticides and when we do that we’re very careful to use medicinal products like baking soda and sulfur along with avoiding applying them to the plants during flowering.


Let’s take a minute to look at another purportedly safe OMRI certified organic pesticide called Pyrethrum. Pyrethrum is made from chrysanthemum flower. Pretty chrysanthemums, that can’t be bad; can it? Turns out that this organic substance when inhaled frequently can cause nervous system damage in humans. When it comes down to it, one needs to know their grower and confirm that only the most benign of pesticides are used, if at all.

In the end, I guess pesticide misuse shouldn’t come as a surprising given the money involved. This is especially true given that harmful insect or fungal infestations can get out of control in a matter of days for indoor grows – outdoor grows have a couple of weeks. Outdoor plants are much more resistant. Competing bugs like ants, ladybugs, and wasps along with beneficial microbes, like oxygen-loving bacteria and fungi, tend to keep harmful bugs and microbes in check. Sun-grown (outdoor) plants develop a level of natural resistance compared to their more fragile indoor counterparts. Note: For the sake of this article, pesticide refers to applications that target insects and not fungi.

The article Into the Weeds: Regulating Pesticides in Cannabis sums up the current state of affairs nicely when they write, “In California and elsewhere, cannabis has long been grown with the help of large quantities of pesticides, including some intended only for ornamental plants and many that are associated with cancer or other serious health effects. But cannabis yields are valuable, and losing a crop to mites or mold means forfeiting many thousands of dollars. Growing plants indoors to escape detection often increases the risk that insect infestations and harmful microbes will spread quickly. For illicit growers with little knowledge of other methods and no regulatory oversight, it is easier and cheaper just to spray”.

Pesticide Testing Limitations

Alright, so a person really does need to insist upon seeing pesticide labs for the cannabis they’re considering buying. Setting aside the fact that even organic pesticides have their issues, the testing itself is far from infallible. Currently, regulation for testing cannabis for pesticides varies from state to state with many states having no regulation. In states with the greatest regulation like California, that recently increased the number of tested pesticides from 21 to 66, the number of pesticides tested still falls short of Canadian regulations that require testing for 100 pesticides.

While testing for 66 or 100 pesticides is helpful, the fact of the matter is that there are thousands of pesticides available. Sad as it is to say, there are no doubt unscrupulous and greedy growers that are intentionally selecting inexpensive pesticides not currently being tested that are harmful for people. In other words, just because test results come back clean, doesn’t mean pesticides haven’t been used. It only means the limited number of pesticides tested for are not present.

On top of this, the report by Oregon Health Authority on Contaminant Testing states that “ No scoring system can perfectly condense the complexity of pesticide toxicology…” And that, “the work group did not have time or resources for an in-depth assessment of each active ingredient in all its formulations”. The bottom line is that no amount of regulation will ever be able to ensure your cannabis is clean and this is why it’s so important to “know your grower”.

Cotton Filter

Tip: Should you ever find yourself in a place where you’re about to smoke, or vape, questionable cannabis, in Pesticide Use in Marijuana Production: Safety Issues and Sustainable Options they write, “… that up to 69.5% of pesticide residues can remain in smoked marijuana. Filtering the smoke through water showed only a slight reduction in pesticide residues. However, when filtered through cotton, pesticide levels were similar to levels in tobacco, with 1-11% of tested pesticides reaching the user”. In other words, use a cotton filter.

Outdoor Versus Indoor Cannabis Series

  1. Outdoor vs Indoor Cannabis
  2. Chemical vs Organic Fertilizer
  3. Cannabis and Mold
  4. Heavy Metals in Cannabis
  5. Pestices in Cannabis

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