The Globe and Mail reported today that myclobutanil, a banned pesticide, has been found in medical cannabis grown by Toronto-based licensed producer Mettrum Ltd. but neither the company or Health Canada informed the public.

Myclobutanil, a chemical that emits poisonous hydrogen cyanide (also known as prussic acid) when heated, is also prohibited for use on legal cannabis in Colorado, Washington and Oregon.

On Nov. 1, Mettrum announced a voluntary recall of their product after a review by Health Canada found it contained pyrethrin, which is used as an insecticide on crops but is not approved for use on medical cannabis. Mettrum said the chemical was used by mistake because it was not listed on the ingredients of a foliar spray the LP purchased from a third party.

“Quality, purity and transparency are Mettrum’s top priorities, which is why we have initiated a voluntary recall of the exposed product and are reaching out directly to all impacted clients,” said Mettrum CEO Michael Haines at the time. “While the ingredient is not harmful and there is no negative effect on product quality and safety, we are doing everything possible to ensure client satisfaction and confidence is upheld.”

But after samples underwent further testing, Health Canada researchers discovered cannabis samples also contained myclobutanil, which is a widely known banned substance.

It was only after the LP sent automated phone messages to customers mentioning myclobutanil that a reporter was tipped off.

Read the full story by Grant Robertson at the Globe & Mail.