Contaminants In Cannabis Concentrates: A Cause For Concern

Over 80 percent of the 57 concentrate samples tested in a recent study contained some amount of pesticides and or residual solvents

According to a recent study in the Journal of Toxicological Sciences, cannabis concentrates may contain pesticides and toxic solvents which remain as residue from the manufacturing process.
In order to address the scarcity of research on cannabis concentrates, The Werc Shop, a cannabis testing lab, collaborated with the University of South California to analyse cannabis concentrates for their cannabinoid, pesticide, and solvent content. They utilized 57 samples of cannabis concentrates from California medicinal cannabis users. Forty-eight of these being solvent-based concentrates while the remainder were dry or water-based hash samples.

The THC content of the 9 hash samples ranged from 50-65%, while the concentrates varied more widely. Most of the concentrates had THC content between 65-75%, while seven of them had less than 40% THC, including one sample with less than 5%. Five samples in the concentrate group had high CBD content, but otherwise the median was 1% CBD for both hash and concentrates.While the hash samples were “exceptionally clean” and did not contain any residual solvents or pesticides, the same could not be said for the concentrates. Over 80% of the concentrates were found to contain residual solvents, including isopentane, butane, heptane, propane, and other solvents. Additionally, nearly 40% of the concentrate samples contained pesticides. The most common was paclobutrazol, a plant growth regulator, and bifenthrin and myclobutanil were also detected.


A second experiment was conducted to evaluate how efficiently THC is transferred from a cannabis concentrate to the vapor stream inhaled by the user during dabbing, in which cannabis concentrates are applied to a hot platform and the resulting vapor inhaled through a bong or water pipe. Using a mechanical lung system, the researchers determined that approximately 40% of the available THC content was captured, though there are differences in transfer efficiency depending on the kind of concentrate that is used. Most importantly, transfer efficiency is extremely dependent on individual user variables such as lung surface area and how long the breath is held. Nonetheless, this result should be a useful benchmark for doctors and medical cannabis patients looking to determine how to dose when working with dabbing as a method of ingestion.



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