Difference between revisions of "Template:Past, Present, and Future of Cannabis Laboratory Testing and Regulation in the United States/Laboratory testing of cannabis/Analytical aspects of cannabis"

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===3.1 Analytical aspects of cannabis===
===3.1 Analytical aspects of cannabis===
====Cannabinoids====
====3.1.1 Cannabinoids====
As of mid-2015, researchers have identified 104 of the more than 750 constituents of ''[[Cannabis sativa]]'' as cannabinoids<ref name="RadwanIso15">{{cite journal |title=Isolation and pharmacological evaluation of minor cannabinoids from high-potency ''Cannabis sativa'' |journal=Journal of Natural Products |author=Radwan, M.M.; ElSohly, M.A.; El-Alfy, A.T. et al. |volume=78 |issue=6 |pages=1271-6 |year=2015 |doi=10.1021/acs.jnatprod.5b00065 |pmid=26000707 |pmc=PMC4880513}}</ref>, active chemical compounds that act in a similar way to compounds our body naturally produces, and new cannabinoids continue to be identified during cannabis research.<ref name="MudgeChemo18">{{cite journal |title=Chemometric Analysis of Cannabinoids: Chemotaxonomy and Domestication Syndrome |journal=Scientific Reports |author=Mudge, E.M.; Murch, S.J.; Brown, P.N. |volume=8 |page=13090 |year=2018 |doi=10.1038/s41598-018-31120-2}}</ref><ref name="CittiANovel19">{{cite journal |title=A novel phytocannabinoid isolated from Cannabis sativa L. with an in vivo cannabimimetic activity higher than Δ9-tetrahydrocannabinol: Δ9-Tetrahydrocannabiphorol |journal=Scientific Reports |author=Citti, C.; Linciano, P.; Russo, F. et al. |volume=9 |at=20335 |year=2019 |doi=10.1038/s41598-019-56785-1}}</ref> Many of our body's cells have cannabinoid receptors capable of modulating neurotransmitter release in the brain and other areas.<ref name="WHOTheHealth16">{{cite book |url=http://www.who.int/substance_abuse/publications/cannabis/en/ |title=The health and social effects of nonmedical cannabis use |author=World Health Organization |editor=Hall, W.; Renström, M.; Poznyak, V |publisher=World Health Organization |pages=95 |year=2016 |isbn=978921510240}}</ref> The plant's cannabinoids vary, with each bonding to specific receptors in our body, providing differing effects. From a theoretical and medical standpoint, crafting a strain of cannabis that has specific cannabinoids that can aid with a particular malady, while also carefully reproducing the grow conditions to consistently make that [[Cannabis strains|strain]] in the future, is a desirable but difficult goal to achieve.<ref name="RahnCannab14">{{cite web |url=https://www.leafly.com/news/cannabis-101/cannabinoids-101-what-makes-cannabis-medicine |title=Cannabinoids 101: What Makes Cannabis Medicine? |work=Leafly - Cannabis 101 |author=Rahn, B. |publisher=Leafly Holdings, Inc |date=22 January 2014 |accessdate=03 February 2017}}</ref> However, even as new strains are developed, identifying an existing strain effectively has its own set of challenges, as Mudge ''et al.'' point out: "the total &#91;[[tetrahydrocannabinol]]&#93; and &#91;[[cannabidiol]]&#93; content is not sufficient to distinguish strains &#91;though&#93; a combination of targeted and untargeted [[Chemometrics|chemometric]] approaches can be used to predict cannabinoid composition and to better understand the impact of informal breeding program and selection on the [[phytochemical]] diversity of cannabis."<ref name="MudgeChemo18" />
As of mid-2015, researchers have identified 104 of the more than 750 constituents of ''[[Cannabis sativa]]'' as cannabinoids<ref name="RadwanIso15">{{cite journal |title=Isolation and pharmacological evaluation of minor cannabinoids from high-potency ''Cannabis sativa'' |journal=Journal of Natural Products |author=Radwan, M.M.; ElSohly, M.A.; El-Alfy, A.T. et al. |volume=78 |issue=6 |pages=1271-6 |year=2015 |doi=10.1021/acs.jnatprod.5b00065 |pmid=26000707 |pmc=PMC4880513}}</ref>, active chemical compounds that act in a similar way to compounds our body naturally produces, and new cannabinoids continue to be identified during cannabis research.<ref name="MudgeChemo18">{{cite journal |title=Chemometric Analysis of Cannabinoids: Chemotaxonomy and Domestication Syndrome |journal=Scientific Reports |author=Mudge, E.M.; Murch, S.J.; Brown, P.N. |volume=8 |page=13090 |year=2018 |doi=10.1038/s41598-018-31120-2}}</ref><ref name="CittiANovel19">{{cite journal |title=A novel phytocannabinoid isolated from Cannabis sativa L. with an in vivo cannabimimetic activity higher than Δ9-tetrahydrocannabinol: Δ9-Tetrahydrocannabiphorol |journal=Scientific Reports |author=Citti, C.; Linciano, P.; Russo, F. et al. |volume=9 |at=20335 |year=2019 |doi=10.1038/s41598-019-56785-1}}</ref> Many of our body's cells have cannabinoid receptors capable of modulating neurotransmitter release in the brain and other areas.<ref name="WHOTheHealth16">{{cite book |url=http://www.who.int/substance_abuse/publications/cannabis/en/ |title=The health and social effects of nonmedical cannabis use |author=World Health Organization |editor=Hall, W.; Renström, M.; Poznyak, V |publisher=World Health Organization |pages=95 |year=2016 |isbn=978921510240}}</ref> The plant's cannabinoids vary, with each bonding to specific receptors in our body, providing differing effects. From a theoretical and medical standpoint, crafting a strain of cannabis that has specific cannabinoids that can aid with a particular malady, while also carefully reproducing the grow conditions to consistently make that [[Cannabis strains|strain]] in the future, is a desirable but difficult goal to achieve.<ref name="RahnCannab14">{{cite web |url=https://www.leafly.com/news/cannabis-101/cannabinoids-101-what-makes-cannabis-medicine |title=Cannabinoids 101: What Makes Cannabis Medicine? |work=Leafly - Cannabis 101 |author=Rahn, B. |publisher=Leafly Holdings, Inc |date=22 January 2014 |accessdate=03 February 2017}}</ref> However, even as new strains are developed, identifying an existing strain effectively has its own set of challenges, as Mudge ''et al.'' point out: "the total &#91;[[tetrahydrocannabinol]]&#93; and &#91;[[cannabidiol]]&#93; content is not sufficient to distinguish strains &#91;though&#93; a combination of targeted and untargeted [[Chemometrics|chemometric]] approaches can be used to predict cannabinoid composition and to better understand the impact of informal breeding program and selection on the [[phytochemical]] diversity of cannabis."<ref name="MudgeChemo18" />


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* '''CBN ([[Cannabinol]])''': CBN is mildly psychoactive at best and appears only in trace amounts in ''Cannabis sativa'' and ''[[Cannabis indica]]''. It occurs largely as a metabolite of THC and tends to have one of the strongest sedative effects among cannabinoids. It shows promise as a treatment for insomnia, glaucoma, and certain types of pain.
* '''CBN ([[Cannabinol]])''': CBN is mildly psychoactive at best and appears only in trace amounts in ''Cannabis sativa'' and ''[[Cannabis indica]]''. It occurs largely as a metabolite of THC and tends to have one of the strongest sedative effects among cannabinoids. It shows promise as a treatment for insomnia, glaucoma, and certain types of pain.


====Terpenes====
====3.1.2 Terpenes====
Mandated lab testing of terpenes—volatile organic compounds that distinctly affect cannabis aroma and taste—is done primarily as a way to ensure proper labeling of cannabis and related products, including extracts and concentrates, so buyers have confidence in what they are purchasing.<ref name="HabibTesting13">{{cite web |url=http://lcb.wa.gov/publications/Marijuana/BOTEC%20reports/1c-Testing-for-Psychoactive-Agents-Final.pdf |format=PDF |title=Testing for Psychoactive Agents |author=Habib, R.; Finighan, R.; Davenport, S. |publisher=BOTEC Analysis Corp |date=24 August 2013 |accessdate=08 February 2017}}</ref><ref name="CMTLabs">{{cite web |url=http://www.cmtlaboratory.com/test-services/tests-offered/ |title=Tests Offered |publisher=CMT Laboratories |accessdate=08 February 2017}}</ref><ref name="WercShop">{{cite web |url=http://thewercshop.com/services/terpene-profiling-services/ |title=Terpene Profiling Services |publisher=The Werc Shop |accessdate=08 February 2017}}</ref> However, additional lab research goes into terpenes as they also show potentially useful pharmacological properties<ref name="HabibTesting13" /><ref name="WercShop" /><ref name="AndreCannabis16">{{cite journal |title=''Cannabis sativa'': The plant of the thousand and one molecules |journal=Frontiers in Plant Medicine |author=Andre, C.M.; Hausman, J.-F.; Guerriero, G. |volume=7 |pages=19 |year=2016 |doi=10.3389/fpls.2016.00019 |pmid=26870049 |pmc=PMC4740396}}</ref>, and they demonstrate synergies (referred to at times as the "entourage effect") with cannabinoids that largely still require further exploration.<ref name="CassidayTheHighs16" /><ref name="AndreCannabis16" /><ref name="WercShop" /><ref name="WachsbergerTerpene16">{{cite web |url=http://www.bloomcityclub.com/terpine-testing-the-future-of-cannabis-is-here/ |title=Terpene Testing: The future of Cannabis is here |author=Wachsberger, K. |work=Bloom Blog |publisher=Bloom City Club |date=02 February 2016 |accessdate=08 February 2017}}</ref> Testing for specific terpenes (discussed later) is less of a standardized practice, though it's rapidly improving.<ref name="HabibTesting13" /> Commonly tested terpenes by third-party testing labs include<ref name="WercShop" /><ref name="CMTLabs" /><ref name="AndreCannabis16" /><ref name="CassidayTheHighs16" /><ref name="RahnUnder14" /><ref name="SCLabs">{{cite web |url=http://sclabs.com/terpene-analysis/ |title=Terpene Analysis |publisher=SC Labs, Inc |accessdate=08 February 2017}}</ref>:
Mandated lab testing of terpenes—volatile organic compounds that distinctly affect cannabis aroma and taste—is done primarily as a way to ensure proper labeling of cannabis and related products, including extracts and concentrates, so buyers have confidence in what they are purchasing.<ref name="HabibTesting13">{{cite web |url=http://lcb.wa.gov/publications/Marijuana/BOTEC%20reports/1c-Testing-for-Psychoactive-Agents-Final.pdf |format=PDF |title=Testing for Psychoactive Agents |author=Habib, R.; Finighan, R.; Davenport, S. |publisher=BOTEC Analysis Corp |date=24 August 2013 |accessdate=08 February 2017}}</ref><ref name="CMTLabs">{{cite web |url=http://www.cmtlaboratory.com/test-services/tests-offered/ |title=Tests Offered |publisher=CMT Laboratories |accessdate=08 February 2017}}</ref><ref name="WercShop">{{cite web |url=http://thewercshop.com/services/terpene-profiling-services/ |title=Terpene Profiling Services |publisher=The Werc Shop |accessdate=08 February 2017}}</ref> However, additional lab research goes into terpenes as they also show potentially useful pharmacological properties<ref name="HabibTesting13" /><ref name="WercShop" /><ref name="AndreCannabis16">{{cite journal |title=''Cannabis sativa'': The plant of the thousand and one molecules |journal=Frontiers in Plant Medicine |author=Andre, C.M.; Hausman, J.-F.; Guerriero, G. |volume=7 |pages=19 |year=2016 |doi=10.3389/fpls.2016.00019 |pmid=26870049 |pmc=PMC4740396}}</ref>, and they demonstrate synergies (referred to at times as the "entourage effect") with cannabinoids that largely still require further exploration.<ref name="CassidayTheHighs16" /><ref name="AndreCannabis16" /><ref name="WercShop" /><ref name="WachsbergerTerpene16">{{cite web |url=http://www.bloomcityclub.com/terpine-testing-the-future-of-cannabis-is-here/ |title=Terpene Testing: The future of Cannabis is here |author=Wachsberger, K. |work=Bloom Blog |publisher=Bloom City Club |date=02 February 2016 |accessdate=08 February 2017}}</ref> Testing for specific terpenes (discussed later) is less of a standardized practice, though it's rapidly improving.<ref name="HabibTesting13" /> Commonly tested terpenes by third-party testing labs include<ref name="WercShop" /><ref name="CMTLabs" /><ref name="AndreCannabis16" /><ref name="CassidayTheHighs16" /><ref name="RahnUnder14" /><ref name="SCLabs">{{cite web |url=http://sclabs.com/terpene-analysis/ |title=Terpene Analysis |publisher=SC Labs, Inc |accessdate=08 February 2017}}</ref>:


Line 44: Line 44:
* [[Terpinene|Terpinolene]]
* [[Terpinene|Terpinolene]]


====Contaminates====
====3.1.3 Contaminates====
Generally speaking, a [[Contamination|contaminate]] is an unwanted substance that may show up in the final product, be it recreational marijuana or a pharmaceutical company's therapeutic tincture. The following are examples of contaminates that laboratories may test for in cannabis products.  
Generally speaking, a [[Contamination|contaminate]] is an unwanted substance that may show up in the final product, be it recreational marijuana or a pharmaceutical company's therapeutic tincture. The following are examples of contaminates that laboratories may test for in cannabis products.  



Revision as of 15:06, 27 March 2020

3. Laboratory testing of cannabis

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Analyzing the chemical constituents of marijuana is a difficult task due to its matrix, and the task becomes even more difficult when it's added to food and other matrix types, requiring established and consistent methods for testing.[1][2] As mentioned previously, regulators, users, and the testing industry are calling for improved standardization of both the production and testing of medical and recreational marijuana. Without proper testing, several issues are bound to arise[3][4][5][6][7][8]:

  • label claims may not match actual contents;
  • contaminants may linger, causing illness or even death;
  • chemical properties and medicinal benefits of specific strains and their unique cannabinoid-terpene profiles can't be isolated; and
  • research on potential therapeutic qualities can't be replicated, hindering scientific progress.

In 2011—a year before any U.S. state had enacted broad legalization of recreational marijuana—California NORML reported that its assessment of analytical cannabis testing laboratories' accuracy found that while California labs broadly reached +/- 20 percent consistency from a replicate sample, three out of 10 provided unfavorable results on at least half of their tests. Similar wide-ranging discrepancies were also found among edibles, extracts, and tinctures, and NORML found that none of the labs could reach two decimal points precision of cannabinoid results despite laboratory claims stating otherwise.[8] Another report out of the state of Washington in January 2015, not long after recreational marijuana sales to the public (requiring accredited lab testing prior) began[9], found blind tests of recreational marijuana at dispensaries could range as much as 7.5 percent in accuracy from its corresponding label.[4] Further issues in 2016 with alleged partiality by some Washington testing laboratories prompted emergency proficiency testing rules to be enacted.[10][11] ("Proficiency testing" essentially requires a laboratory in question to test a sample with known properties, and then those results are compared to those of a neutral third-party lab testing the same sample.) Additional testing problems in Alaska and Washington labs in late 2017 found high disparities between two different testing labs, as well as a laboratory that couldn't "properly perform a coliform test that looks for bacteria."[12]

These discrepancies and deficiencies highlight the growing need for homogenization of testing methods and procedures, if not nationally at least across an entire state. Such homogenization would, in theory, not only positively affect the quality of product but also provide greater consumer confidence that label and product match. As Marketing Director Scott Kuzdzal of Shimadzu pointed out during a January 2017 webinar on analytic testing of cannabis, poor sample preparation, lack of thorough testing, and the manual process itself—which can introduce user error, particularly when good laboratory practices aren’t used—all can contribute to discrepancies between label and product.[13] When dispensaries, edible manufacturers, and supplement companies perform insufficient lab testing or overstate claims on labels, it reduces consumer confidence, and both state and federal authorities—including the U.S. Food and Drug Administration (FDA)—have to interject.[10][11][14]

As was mentioned at the end of the previous section on state regulation, efforts to improve testing methods and procedures, with the goal of seeing the best of them become standards, are ongoing. Where are those efforts now, and where are they going? Before we can examine that, we first need to briefly look at what aspects of cannabis are actually being analyzed.


3.1 Analytical aspects of cannabis

3.1.1 Cannabinoids

As of mid-2015, researchers have identified 104 of the more than 750 constituents of Cannabis sativa as cannabinoids[15], active chemical compounds that act in a similar way to compounds our body naturally produces, and new cannabinoids continue to be identified during cannabis research.[16][17] Many of our body's cells have cannabinoid receptors capable of modulating neurotransmitter release in the brain and other areas.[18] The plant's cannabinoids vary, with each bonding to specific receptors in our body, providing differing effects. From a theoretical and medical standpoint, crafting a strain of cannabis that has specific cannabinoids that can aid with a particular malady, while also carefully reproducing the grow conditions to consistently make that strain in the future, is a desirable but difficult goal to achieve.[19] However, even as new strains are developed, identifying an existing strain effectively has its own set of challenges, as Mudge et al. point out: "the total [tetrahydrocannabinol] and [cannabidiol] content is not sufficient to distinguish strains [though] a combination of targeted and untargeted chemometric approaches can be used to predict cannabinoid composition and to better understand the impact of informal breeding program and selection on the phytochemical diversity of cannabis."[16]

Lab testing of cannabinoids is done primarily as a measure of psychoactive "potency," though cannabinoids have many other potential therapeutic uses. Current laboratory testing looks at only a handful of cannabinoids; more research and development of analytical techniques that can quickly and accurately detect and separate the the rest is required.[20] Some of the major cannabinoids tested for include[16][20][21][22]:

  • THC (∆9-Tetrahydrocannabinol): This is the most commonly known cannabinoid found in cannabis, notable for its strong psychoactive effects and ability to aid with pain, sleep, and appetite issues. Included is its analogue ∆8-Tetrahydrocannabinol (which shows notably less strong psychoactive effects than ∆9[23]) and its homologue THCV (Tetrahydrocannabivarin), which tends to appear in trace amounts and has a more pronounced psychoactive effect, but for a shorter duration. THCV shows promise in fighting anxiety, tremors from neurological disorders, appetite issues, and special cases of bone loss. Also notable is Δ9-THCA (Δ9-Tetrahydrocannabinolic acid), a non-psychoactive biosynthetic precursor to THC.
  • CBC (Cannabichromene): This non-psychoactive cannabinoid is found in trace amounts; however, it tends to be markedly more effective at treating anxiety and stress than CBD (see next). It's also notable for its anti-inflamatory properties and potential use for bone deficiencies.
  • CBD (Cannabidiol): CBD is a non-psychoactive component of cannabis, typically accounting for up to 35 to 40 percent of cannabis extracts. It acts as a counter-balance to THC, regulating its psychoactivity. It's been researched as a treatment for anxiety, sleep loss, inflammation, stress, pain, and epilepsy, among other afflictions. Included is its homologue CBDV (Cannabidivarin), which is also non-psychoactive and demonstrates promise as a treatment for epileptic seizures. Also notable is CBDA (Cannabidiolic acid), a non-psychoactive biosynthetic precursor to CBD.
  • CBG (Cannabigerol): This cannabinoid is also non-psychoactive but only appears in trace amounts of cannabis. If has potential as a sleep aid, anti-bacterial, and cell growth stimulant. Also notable is CBGA (Cannabigerolic acid), a non-psychoactive biosynthetic precursor to CBG.
  • CBN (Cannabinol): CBN is mildly psychoactive at best and appears only in trace amounts in Cannabis sativa and Cannabis indica. It occurs largely as a metabolite of THC and tends to have one of the strongest sedative effects among cannabinoids. It shows promise as a treatment for insomnia, glaucoma, and certain types of pain.

3.1.2 Terpenes

Mandated lab testing of terpenes—volatile organic compounds that distinctly affect cannabis aroma and taste—is done primarily as a way to ensure proper labeling of cannabis and related products, including extracts and concentrates, so buyers have confidence in what they are purchasing.[24][25][26] However, additional lab research goes into terpenes as they also show potentially useful pharmacological properties[24][26][27], and they demonstrate synergies (referred to at times as the "entourage effect") with cannabinoids that largely still require further exploration.[7][27][26][28] Testing for specific terpenes (discussed later) is less of a standardized practice, though it's rapidly improving.[24] Commonly tested terpenes by third-party testing labs include[26][25][27][7][22][29]:

3.1.3 Contaminates

Generally speaking, a contaminate is an unwanted substance that may show up in the final product, be it recreational marijuana or a pharmaceutical company's therapeutic tincture. The following are examples of contaminates that laboratories may test for in cannabis products.

Pesticides: Pesticides represent the Wild West of not only growing cannabis but also performing analytical testing on it. One of the core issues, again, is the fact that on the federal level marijuana is illegal. Because it's illegal, government agencies such as the Environmental Protection Agency (EPA) don't test and create standards or guidelines for what's safe when it comes to residual pesticides, let alone how to best test for them.[30][31] Additionally, researchers face their fair share of difficulties obtaining product to test. The end result is we don't know much about how inhalation of pesticide-coated marijuana smoke affects long-term health[30][31], and we have few standard methods for pesticide application and testing.[7][32] With numerous pesticide products and little oversight on what growers apply to their plants, combined with the technical difficulty of testing for pesticides in the lab, pesticides remain one of the most difficult contaminates to test for.[7][32] That said, several classes of of pesticides are commonly applied during cannabis cultivation and can be tested for by labs[21][6][33]:

  • avermectins: functions as an insecticide that is useful against mites, which are a common problem for cultivators
  • carbamates: functions as an insecticide, similar to organophosphates, but with decreased dermal toxicity and higher degradation
  • organophosphates: functions as the base of many insecticides and herbicides, valued for its easy organic bonding
  • pyrethroids: functions as the base of most household insecticides and exhibits insect repellent properties


Solvents: In 2003, Canadian Rick Simpson published a recipe of sorts for preparing cannabis extract via the use of solvents such as naphtha or petroleum ether. Claiming the resulting oil helped cure his skin cancer, others hoping for a cure tried it, and the solvent method of preparation grew in popularity. Dubious healing claims aside, the solvent extraction method remains viable, though it has evolved over the years to include less harmful solvents such as supercritical carbon dioxide, which has low toxicity, low environmental impact, and beneficial extraction properties.[7][34][35] However, chemical solvents are still used, and if not evaporated out properly, the remaining solvents can be particularly harmful to sick patients using the extract. As for what solvents should be tested for, it gets a bit trickier, though Chapter 467 of United States Pharmacopeia and The National Formulary, the Oregon Health Authority's December 2015 technical report on contaminant testing of cannabis, and the Massachusetts Department of Public Health's response to public comments on cannabis testing provide helpful guidance. Listed solvents include benzene, butane, cumene, dimethoxyethane, hexane, and pentane, among others.[6][21][7][33][36][37]


Heavy metals: 2013 research on contaminant testing on the behalf of Washington State provides insights into heavy metals and why they're looked for in cannabis testing. That research, as well as other sources, tell us[6][21][7][38]:

  • Heavy metals contribute to several health problems, including those of a neurological nature.
  • Cannabis can "hyperaccumulate metals from contaminated soils."
  • Research parallels can be found in tobacco research and how the FDA regulates heavy metal content in foods.
  • The most prominently tested heavy metals include arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), mercury (Hg), and nickel (Ni).


Mycotoxins and microorganisms: "The ideal conditions for cannabis growth are also ideal for the growth of potentially harmful bacteria and fungi, including yeast and molds," say Shimadzu's Scott Kuzdzal and William Lipps, "therefore microbial contamination poses health risks to consumers and immunocompromised individuals."[20] In truth, these concerns have already borne out. In fact, the University of California, Davis reported in February 2017 one of its patients had contracted an incurable fungal infection from inhaling aerosolized marijuana. They later tested 20 marijuana samples from Northern California dispensaries—using specialized techniques—and found a wide variety of potentially hazardous microorganisms.[39]

The degree to which such contaminates commonly appear in grown and stored cannabis material and to which microbiological contaminates should be tested is not clear, however. As mentioned previously, neither the U.S. EPA or neighboring Health Canada provide any significant guidance on cannabis testing, including microbiological contaminates.[40] Like heavy metal testing, parallels are drawn from microbial testing guidelines and standards relating to tobacco and food, where they exist.[40] As warm, moist environments are conducive to microorganism growth, maintaining stable moisture levels during cultivation and storage is essential. Regularly measuring water activity—how moist something is—is particularly useful as a front-line preventative tool to better ensure microbial growth is limited.[33] Regardless, testing of some kind is still required by many U.S. states, including for organisms such as[20][21][7][33][39][40][41][42]:

  1. DePalma, A. (10 September 2018). "Challenges of Cannabis Contaminant Testing". Lab Manager. LabX Media Group. https://www.labmanager.com/insights/2018/09/challenges-of-cannabis-contaminant-testing. Retrieved 08 January 2020. 
  2. Cummings, J., "Gurus of Pesticide Residue Analysis [The Cannabis Scientist"] (PDF), The Analytical Scientist (Texere Logo Texere Publishing Ltd) (0218), https://theanalyticalscientist.com/fileadmin/tas/pdf-versions/TCS_Issue4.pdf 
  3. Hazekamp, A.; Fischedick, J.T. (2012). "Cannabis - from cultivar to chemovar". Drug Testing and Analysis 4 (7–8): 660–7. doi:10.1002/dta.407. PMID 22362625. 
  4. 4.0 4.1 Bush, E. (18 February 2015). "World’s strongest weed? Potency testing challenged". The Seattle Times. The Seattle Times Company. http://www.seattletimes.com/seattle-news/worldrsquos-strongest-weed-potency-testing-challenged/. Retrieved 08 January 2020. 
  5. Rutsch, P. (24 March 2015). "Quality-Testing Legal Marijuana: Strong But Not Always Clean". Shots. National Public Radio. http://www.npr.org/sections/health-shots/2015/03/24/395065699/quality-testing-legal-marijuana-strong-but-not-always-clean. Retrieved 08 January 2020. 
  6. 6.0 6.1 6.2 6.3 Kuzdzal, S.; Clifford, R.; Winkler, P.; Bankert, W. (December 2017). "A Closer Look at Cannabis Testing" (PDF). Shimadzu Corporation. https://www.ssi.shimadzu.com/sites/ssi.shimadzu.com/files/Industry/Literature/Shimadzu_Whitepaper_Emerging_Cannabis_Industry.pdf. Retrieved 08 January 2020. 
  7. 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 Cassiday, L. (October 2016). "The Highs and Lows of Cannabis Testing". INFORM. American Oil Chemists' Society. https://www.aocs.org/stay-informed/read-inform/featured-articles/the-highs-and-lows-of-cannabis-testing-october-2016. Retrieved 08 January 2020. 
  8. 8.0 8.1 "How Accurate Is Cannabis Potency Testing?". California NORML. 21 September 2011. https://www.canorml.org/business-resources-for-cannabis-brands/how-accurate-is-cannabis-potency-testing/. Retrieved 08 January 2020. 
  9. "FAQs on I-502". Washington State Liquor and Cannabis Board. http://lcb.wa.gov/mj2015/faqs_i-502. Retrieved 03 February 2017. 
  10. 10.0 10.1 Young, B. (5 January 2016). "Some pot labs in state failed no pot at all, says scientist". The Seattle Times. The Seattle Times Company. http://www.seattletimes.com/seattle-news/marijuana/some-pot-labs-in-state-failed-no-pot-at-all-says-scientist/. Retrieved 03 February 2017. 
  11. 11.0 11.1 Coughlin-Bogue, T. (11 March 2016). "To Combat Inconsistency, Washington Testing Labs Turn to Self-Policing". Leafly - Politics. Leafly Holdings, Inc. https://www.leafly.com/news/politics/to-combat-claims-of-inconsistency-washington-testing-labs-turn-to. Retrieved 03 February 2017. 
  12. Ritchie, H. (29 April 2018). "Inconsistency in Cannabis Lab Testing". Terpenes and Testing Magazine. https://terpenesandtesting.com/category/testing/cannabis-testing-lab-test-inconsistencies/. Retrieved 15 November 2018. 
  13. Kuzdzal, S.A. (19 January 2017). "Webinar: Opportunities & Challenges in Cannabis Analytical Testing". Shimadzu Corporation. Archived from the original on 19 January 2017. http://web.archive.org/web/20170119200158/http://www.shimadzu.com.cn/an/news-events/news/2017/4381.html. Retrieved 03 February 2017. "Source is actual webinar." 
  14. "2016 Warning Letters and Test Results for Cannabidiol-Related Products". Public Health Focus. U.S. Food and Drug Administration. 31 August 2016. http://www.fda.gov/newsevents/publichealthfocus/ucm484109.htm. Retrieved 03 February 2017. 
  15. Radwan, M.M.; ElSohly, M.A.; El-Alfy, A.T. et al. (2015). "Isolation and pharmacological evaluation of minor cannabinoids from high-potency Cannabis sativa". Journal of Natural Products 78 (6): 1271-6. doi:10.1021/acs.jnatprod.5b00065. PMC PMC4880513. PMID 26000707. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=PMC4880513. 
  16. 16.0 16.1 16.2 Mudge, E.M.; Murch, S.J.; Brown, P.N. (2018). "Chemometric Analysis of Cannabinoids: Chemotaxonomy and Domestication Syndrome". Scientific Reports 8: 13090. doi:10.1038/s41598-018-31120-2. 
  17. Citti, C.; Linciano, P.; Russo, F. et al. (2019). "A novel phytocannabinoid isolated from Cannabis sativa L. with an in vivo cannabimimetic activity higher than Δ9-tetrahydrocannabinol: Δ9-Tetrahydrocannabiphorol". Scientific Reports 9: 20335. doi:10.1038/s41598-019-56785-1. 
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