Denver: pesticides found in marijuana products

6 months ago, the city of Denver in the U.S. Colorado, where cannabis is legal, began restricting the pesticides permitted in marijuana products. A Denver Post survey reveals that chemicals are still present in some products sold in dispensaries.

The Denver Post commissioned 8 tests from a private laboratory. Of the products purchased from two different stores, most did not contain pesticides banned by the Colorado Department of Agriculture. But two tests on marijuana concentrates were positive.

The company behind these products, Mahatma Concentrates, acknowledged using one of the banned pesticides, at very low doses. But the levels found were 6 times higher than the level allowed federally on any food, and 1800 times higher than the limit set by Colorado 6 months earlier. The pesticides in question were myclobutanil, imidacloprid and avermectin.

Mahatma Concentrates immediately stopped using the offending pesticide. But some of its products, such as concentrates, are made from grass, in particular pruning waste, which it buys on the secondary market. As for’use of pesticides in its plantations, Mahatma's founder blames a former employee.

A feverish line of defense when some of its stores had already had their plants confiscated when Denver carried out its first tests in March 2015. Over 100,000 plants had been set aside across Denver while pesticide levels in the potting soil fell back to legal levels.

This information highlights a significant public health problem. Products containing high levels of pesticides pose potential health risks for consumers. In fact, this is the biggest long-term risk to these products. The Denver Post's initiative is a brave one, but it's a subject that Colorado authorities need to get to grips with.

The City of Denver has already issued an alert to all cannabis stores. Some have destroyed potentially looted stock, a simple gesture that communicates the cannabis industry's and the city's concern for the health of its customers.