pesticides change flavour

Over the past three to four years, Health Canada has refused one question. The department would not explain why they authorized licensed producers to spray sulphur on flowering cannabis intended for smoking. Finally, following the third attempt, Health Canada admits that pesticides change the flavour.

Shortly after legalization, rules on ACMPR licensed patients sharing seeds was passed back and forth like a ping-pong ball between Health and Justice Canada. Eventually, Health Canada gave a reply. Health Canada’s media department even followed up when asked if they considered the possibility of strange quantum structures (hopfions) in liquid crystals regarding Covid vaccines. The response was admittedly generic. But their media department still replied to the question. In fact, considerations for approving sulphur on cannabis is the only question Health Canada refused to answer — and they did so twice.

Pesticides after combustion

What considerations did the Pest Management Regulatory Agency (PMRA) take when authorizing vaporizable and wettable sulphur-based pesticides for flowering cannabis intended for inhalation (i.e. cannabis in a pre-rolled ‘joint’)?

Before a pesticide product is approved for use in Canada, Health Canada’s PMRA must determine that it has value (for example, that it works as claimed by the manufacturer). And that there are no health and environmental risks of concern. This is the process used for approving all pesticides in Canada, including those registered for use on cannabis.

Specifically, PMRA’s assessment of pesticides considers the toxicity and the level of exposure, which includes the rate, timing and frequency of applications, to characterize risk. When Agrotek Vaporizable Sulphur and NM Bartlett, Wettable Sulphur are used according to label directions, there are no health concerns.:

Tammy  Jarbeau | Senior Media Relations Advisor |Communications and Public Affairs Branch | Health Canada and the Public Health Agency of Canada

Interestingly, the combustion of sulphur produces toxic and deadly gasses known as sulphur dioxide and hydrogen sulphide (H2S). One sulphur product authorized for use in commercial cannabis production gives this warning in the MSDS. Health Canada’s confidence should assume that no residues of environmental sulphur remain on the flowering plants if a producer follows the label.

pesticides change flavour
Diagram of a sulphur burner courtesy of Zhang et Al. 2020.

Sulphur is an oxidizer

Did Health Canada (or the PMRA) consider acceptable limits of sulphur dioxide and hydrogen sulphide when authorizing Vaporizable Sulphur and Wettable Sulphur as IPM strategies on flowering cannabis crops?

Good Production Practices for Cannabis are such that it is best to achieve pest control prior to flower. Application of a pesticide such as sulphur on leaves can leave residues that change the desired flavour profile of the harvested cannabis.

Tammy  Jarbeau

Sulphur and oxygen have similar actions on molecules within cannabis. The former, however, is more dynamic and causes a complex array of chemical reactions. A straightforward explanation is that sulphur impacts the chemical composition of the flower, shifting or degrading terpenes.

Self-regulated solutions

Health Canada is re-evaluating numerous pesticides, including sulphur. Potassium salts and potassium bicarbonate are approved for use on cannabis but currently undergoing the information gathering phase for re-evaluation this year. At the same time, diatomaceous earth finished a consultation for re-evaluation last month. Scheduled the following years is mineral oil as well as Bacillus thuringiensis Berliner ssp. kurstaki (used in AEF Global’s Bioprotec.)

Self-regulation before government oversight is critical. To accomplish this, a producer can strictly use a crop for edible and topical products if they adamantly want to spray sulphur-based pesticides during a late flowering stage. Keep in mind that sulphur turns into sulphides in the gut but only causes gastrointestinal issues after large doses.

Producers should work hard to keep sulphur residues and powdery mildew out of joints, bongs, and those pesky vape pens that combust concentrates. A successful crop requires beneficial insects, better-growing practices, and good genetics. Section 81 of the Cannabis Regulations, however, allows producers to treat Edible Cannabis with products not authorized under the Pest Control Products Act (PCPA).

Let us know in the comments if you think pesticides change more than cannabis’s flavour.


  1. Zhang, Feichi & Heidarifatasmi, Hosein & Harth, Stefan & Zirwes, Thorsten & Wang, Robert & Fedoryk, Michal & Sebbar, Nadia & Habisreuther, Peter & Trimis, Dimosthenis & Bockhorn, Henning. (2020). Numerical evaluation of a novel double-concentric swirl burner for sulfur combustion. Renewable and Sustainable Energy Reviews. 133. 110257. 10.1016/j.rser.2020.110257.