Leading Cannabis Testing Lab Says 86% of California’s Clones Are Contaminated With Pesticides
A research project funded by Steep Hill sought to find where pesticides were introduced in the supply chain, with all arrows pointing towards serious issues with the state’s commercial clones.
Published on September 25, 2017

After more than two decades of operating as the cannabis industry’s unregulated wild, wild west, California is finally getting a set of comprehensive medical and recreational legal weed regulations, but with improper pesticide use and uncertain testing procedures running rampant, is it already too late to start wrangling in the world’s biggest weed market?

According to New Cannabis Ventures, a new study from Steep Hill, one of California’s leading cannabis testing labs, reports that upwards of 85% of marijuana clones, plants harvested from larger “mothers” that are used in both commercial and home grows, were contaminated with pesticide residue.

Because pesticides may be used to preserve the mother plant, researchers found that clones that had never themselves been exposed to pesticides still showed trace amounts of the potentially dangerous chemicals. 

“Pesticide use occurs during clone production, and that use remains present through the growth cycle of the plant, and can be tracked through at least 1 generation of passage.” The study concludes. “Purchasers of the treated clones likely do not know that they can lead to contamination in the harvested product, even if the grower does not apply pesticides in their practice.”

In the study, Steep Hill’s researchers looked at 124 randomly selected clones and found only 14% were completely free from contamination. In the 86% that showed “low (a few to a few tens of ng/g or ppb)” levels of pesticide presence, Myclobutanil was the chemical most frequently detected.

“These results are in keeping with the general trend of Myclobutanil being by far the most often detected pesticide in market ready flower and extracts/concentrates.” The report says.

With a problem so pervasive, California regulators will have their hands full, with Steep Hill hoping to provide any scientific expertise they can to assure safety and consistency in legal cannabis products available to the public.

“When the ‘mothers’ of clones are contaminated with pesticides, particularly those that are systemic, so too are the clone offspring.” CEO Jmîchaeĺe Keller said. “We look forward to working with the California cannabis industry to establish best practices to substantially reduce the need for the use of pesticides as a whole, and to help set the standard for clean clone production in the future.”

Zach Harris
Zach Harris is a writer based in Philadelphia whose work has appeared on Noisey, First We Feast, and Jenkem Magazine. You can find him on Twitter @10000youtubes complaining about NBA referees.
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