What are the reasons for failing pesticide analysis?

Pesticide burden is a relatively new topic in cannabis testing. At Confidence Analytics, we operate an LC-MS/MS instrument to measure pesticide levels. The LC-MS/MS is designed specifically to look for very low levels of many compounds in a short amount of time. We’ve found that pesticides occur at trace levels on most samples submitted for pesticide testing, but relatively few samples have alarming amounts of pesticides present.

There are generally three ways pesticides can wind up on a cannabis plant.

Obviously there is direct application, which in most cases is a very bad idea; direct application would result in levels far exceeding the action levels enforced by the state. Our current record is over 200 ppm of Pyrethrin I. Direct application of pesticides during the early vegetative period will retain lower levels than if applied during late flower, but any direct application is likely to cause a failing result.

Next, there is indirect exposure where plants are grown in a space that once had pesticides directly applied – bug bombs, preventative spraying, etc. Indirect exposure usually results in levels that hover around the action level enforced by the state. Most often, we see quantities in the 0.1 to 0.5 ppm range from this.

Finally, there is incidental exposure. This is most common for outdoor crops grown in areas near other agricultural operations. Wind-blown pesticide dust can slowly accumulate on your plants without your knowledge. Fortunately, incidental exposure results in very low to trace levels of pesticide residue well below the action level, and most people do not consider it a hazard to human health. In about a third to a half of samples, we see less than 5 ppb (0.005 ppm) of pesticides that are more commonly used on apples, cherries, peaches, grapes, and many of the other crops grown commercially in Washington.

If making concentrates, be sure that the system is fully cleaned to prevent any carry-over or cross contamination from occurring between batches.  Product containing pesticide residue can leave traces in an extraction system that have the potential of being carried over into future extraction batches.

The current list for pesticide action levels is here . Several of these listed compounds are found in natural products – specifically Pyrethrins (found in some species of Chrysanthemum), and Abamectin and Spinosad (derived from the natural fermentation of different species of bacteria). The most common pesticide compound we see isn’t technically a pesticide, but a potentiating agent that increases the insect toxicity of certain classes of pesticides – piperonyl butoxide.