Originally published in O’Shaughnessy’s.
RING TEST: A standard procedure in the analytical testing industry for external quality-control assurance, in which identical samples are sent to a variety of testing facilities in order to compare results.
Want to know the potency of your medicine? How much, if any CBD, does it contain? Has it been sprayed with dangerous pesticides? Is it infested by molds or bacteria? The only way to answer these questions for sure is to have it tested by an analytical lab.
Many labs now offer testing services for the medical cannabis industry. How accurate are the results they provide?
Our investigation was launched in the winter of 2010/11. An identical set of samples was submitted to 10 labs. The labs were asked to measure THC, CBD, and CBN, the three major cannabinoids for which testing is generally available. To encourage participation, the identity of the labs was kept confidential; in this report they are identified by numbers only (Lab 1, 2 etc.).
In most cases, lab results were consistent to within 20% of each other. To some degree, the differences in results might be explained by natural variations in the consistency of the cannabis samples used; to some degree, by differences in lab procedures. In certain cases, there were glaring discrepancies suggesting laboratory error. Three of the 10 labs performed poorly on half the tests. Particularly in the case of liquid alcohol extracts, test results were troublingly inconsistent. Nevertheless, the general results showed good agreement between most lab results involving herbal samples. Lab performance can be expected to improve in the future as the industry responds with improved standards.
This piece was reprinted by Project CBD with permission. It may not be reproduced in any form without approval from the source.
| Attachment | Size |
|---|---|
 How Accurate is Potency Testing? | 634.95 KB |
Recommended reading
Lab testing, safety protocols, adverse events reporting, and regulatory standards for the cannabis industry.
Project CBD science advisor Jahan Marcu, PhD, reports on the hidden dangers of propylene glycol and vape pens that smolder.
Our organization outlines our concerns with the State of California’s proposed regulations for cannabis testing regarding pesticides, heavy metals, and solvents and our recommendations for amending them. We believe the following recommendations will benefit patients, recreational users, and people working in the industry.
A new article from the California Department of Pesticide Regulations (CDPR) warns of the dangers of cannabis because it may be contaminated with organophosphate pesticides (e.g. chlorpyrifos, glyphosate). The CDPR walks through what could happen if a pregnant woman uses chlorpyrifos-contaminated cannabis. Pesticide toxicity is important concern, but this is a bit ironic coming from the CDPR, which has consistently failed to provide sensible limits for pesticides on cannabis.
