The cannabis plant produces cannabinoids in the form of acids, like delta-9-tetrahydrocannabinolic acid (∆9-THC-A). It does not enzymatically produce a single molecule of delta-9-tetrahydrocannabinol (∆9-THC). That does not mean, that there is no ∆9-THC in the flowering tops; ∆9-THC-A and other acidic cannabinoids get converted into their neutral forms via heat, light or exposure to oxygen.
The presence and ratio of acid: neutral cannabinoids can also be an indicator of storage and age of the analysed cannabis. Improper storage can decrease the level of acidic cannabinoids, which in turn increases the level of neutral cannabinoids. Other volatile compounds, such as monoterpenes, are also susceptible to improper storage.
By doing a quick search and calculation from 15 analysed samples of type 1 (high THC) from Analytical 360’s archive website , the average ∆9-THC (compared to ∆9-THC-A) was 7,1% (2,4 – 12,4, n=15). From 5-10% of the total THC is usually in the neutral form, in properly stored cannabis.
If we compare this data to a study by Wang et al. , where they analysed DEA confiscated samples and samples from the University of Mississippi, the average % of ∆9-THC was 33,2% (19,2 – 54,7, n=11) in the DEA samples and 28,5% (10,5 – 41, n=6) in the Mississippi samples. While the number of samples analysed is relatively small, it can still give us an indication of the storage and handling of the plant materials.
Even worse results can be seen in a recently published study by Souleman et al. , where they analysed confiscated cannabis flowers and hashish. In the flower samples, 80% of the total THC was in the form of ∆9-THC and only 20% of ∆9-THC-A.
Another usually used indicator of cannabis poor storage is cannabinol (CBN), the oxidative product of ∆9-THC (or CBN-A). The samples form 360 analytical had no detectable CBN, while all the DEA samples had CBN present, on average 0,79 % (0,18 – 1,44, n=11). Only 2 of the 6 Mississippi samples had detectable CBN and no information on CBN levels was included in the Egyptian study.
In the discussion section of the same study they also commented that “marijuana, has shown a higher THC content than we expected based on the world drug reports.” If we compare the 11% total THC that hey reported, to the other newer published studies 12%  13.9%  [ 14.88% , we can see, that it was in the lower end of potency for today’s standards.
A more indicative report, of the potency of the cannabis present on the market, can be gathered form analytical reports from laboratories. As an example, in the 15 samples analysed by 360, the average of total THC was 18% (13,25 – 23,22, n=15).
1. Analytical 360 https://cbd.analytical360.com/
2. Wang YH, Avula B, ElSohly MA, Radwan MM, Wang M, Wanas AS, Mehmedic Z, Khan IA. Quantitative Determination of Δ9-THC, CBG, CBD, Their Acid Precursors and Five Other Neutral Cannabinoids by UHPLC-UV-MS. Planta Med. 2017 Dec 20.
3. Ahmed M.A. Souleman, Alaa El-Din M. Gaafar, Omar M. Abdel-Salam, Shaimaa A. El Shebiney. Determination of delta-9-tetrahydrocannabinol content of cannabis seizures in Egypt. Asian Pacific Journal of Tropical Medicine, Volume 10, Issue 3, March 2017, Pages 311-314
4. Mahmoud A.El Sohlya, Zlatko Mehmedica, Susan Fostera, Chandrani Gona, Suman Chandraa, James C.Churchb. Changes in Cannabis Potency Over the Last 2 Decades (1995–2014): Analysis of Current Data in the United States. Biological Psychiatry, Volume 79, Issue 7, 1 April 2016, Pages 613-619
5. D.J. Potter, P. Clark, M.B. Brown. Potency of delta 9-THC and other cannabinoids in cannabis in England in 2005: implications for psychoactivity and pharmacology. J Forensic Sci, 53 (1) (2008), pp. 90-94
6. W. Swift, A. Wong, K.M. Li, J.C. Arnold, I.S. McGregor. Analysis of cannabis seizures in NSW, Australia: cannabis potency and cannabinoid profile. PLoS One, 8 (7) (2013), p. e70052
7. Lewis, Melissa & Yang, Yi & Wasilewski, Ewa & A. Clarke, Hance & P. Kotra, Lakshmi. (2017). Chemical Profiling of Medical Cannabis Extracts. ACS Omega. 2. 6091-6103.