Only So Green: Pesticides in Cannabis Clones

As the cannabis industry grows rapidly, so do many of the testing requirements. States have discovered an expanding pesticide problem in cannabis, and as a result government agencies are looking to lower the maximum allowable limits from state to state. The testing for pesticides gets especially stringent in samples that are supposed to be pesticide-free, such as samples advertised as organic or ‘clean green.’ Nonetheless, pesticides at low levels, especially at 10s of parts per billion or less, turn up in some of these samples. So, scientists at Steep Hill Labs—Anthony Torres, Wilson Linker, Donald Land and Reggie Gaudino—went in search of the source. They wanted to see how the pesticides got in those samples, when growers were claiming they grew their product organically, or pesticide free.

In fact, analyses at Steep Hill Labs were increasingly showing pesticides at worrisome levels in samples that should not have contaminants. This includes pesticides in cannabis flowers and leaves, as well as products made from raw ingredients that were guaranteed to not include pesticides. 

The scientists collected and purchased a range of cannabis clones—124 in all. After sample preparation, the scientists analyzed them with a Shimadzu NeXera X2 LCMS8050 HPLC, which is a triple quadrupole mass spectrometer. The team analyzed the data with Shimadzu Lab Solutions software. The data analysis included rigorous calibration standards. 

After analyzing all 124 clones, only 13.7% of clones were pesticide free. Moreover, 77.4% failed California’s pesticide requirements for cannabis. “This is a significant number of failures, at the clone level,” the scientists reported (http://landing.steephill.com/cleanclones). “This data was the first revelation that there would be serious problems in the California Cannabis supply chain if the very starting material from which the Cannabis was being sourced for large scale production was already contaminated with pesticides that would fail current regulations.” The results turned up a variety of pesticides, and the one found the most was Myclobutanil, which is used to treat mold infections.

Beyond the supply-chain problems that these results suggest, even more concerns arise from this work. Low levels—the kind found in these samples—might dissipate from environmental conditions before the plants were even harvested, which could lead to acceptable products. However,  according to the Steep Hill scientists, “many pesticides are systemic or exist in the soil/growth media, away from many of the very environmental influences that would degrade/inactivate the pesticides and persist far longer than published dissipation rates.” Unfortunately, the team reported that this means “there is not a very high probability that the levels seen in some of the clones tested would be remediated by any natural/environmental exposure means.”

The take-home message is that growing from seed might be the only way to ensure starting with clean cannabis, but if a vendor must start with clones, they should be tested before growing. “Finding clean clones may be difficult given the data that we have seen,” says Gaudino. “ The chemicals are already in the environment due to other agricultural crops where these pesticides are approved for use, and they remain in the soil, the rockwool and other agricultural environs.”

Consequently, the only way to ensure being a ‘green grower’ is to test cannabis clones.