92% of illegal cannabis in Canada contains pesticides

A recent study published in the Journal of Cannabis Research revealed the extent of pesticides in cannabis illegal and legal in Canada.

In « High levels of pesticides found in illicit cannabis inflorescence compared to licensed samples in Canadian study using expanded 327 pesticides multiresidue method« the researchers compared 36 samples of cannabis from licensed dispensaries and 24 from an illegal trade (which was seized by law enforcement and submitted to Health Canada for laboratory testing in 2021).

The researchers looked for traces of 327 different pesticides in the samples and found that a large number of illegal cannabis samples contained harmful chemicals.

«Pesticides were detected in 92% of Canadian illicit cannabis inflorescence samples, with 23 unique pesticide active ingredients quantified,» the study explains. «Four pesticides and synergists: myclobutanil, paclobutrazol, piperonyl butoxide and pyrethrins, were detected at high sampling frequencies, ranging from eight to 17 times in a total of 24 illicit samples.»

They also noted that one illegal sample contained nine pesticide ingredients, but that on average, illegal samples contained 3.7 different pesticides, with 87% of them containing more than one pesticide.

The researchers provided a table showing which pesticides were found in the legal and illegal samples. Only 6 % of the legal samples tested positive for pesticides, including only dichlobenil and myclobutanil.

Finally, they note that studies of this nature are not yet common. «To the authors» knowledge, this study is the only in-depth multi-residue analysis of pesticides that compares pesticides in legal and illegal cannabis markets in a national jurisdiction where cannabis has been legalized," the study concludes.

«Although this is a small study, our results support the Government of Canada's message that consumption of illegal products could lead to adverse effects and other serious harms. Tests conducted on illegal cannabis revealed the presence of contaminants such as pesticides and unacceptable levels of bacteria, lead and arsenic.».