Updated: Oct 9
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A September 2022 research study conducted at Arizona State University entitled "Comparison of State-level Regulations for Cannabis Contaminants & Implications for Public Health" that was published in the journal Environmental Health Perspectives investigated the potential threat of contamination of cannabis products and how it may negatively impact consumers and patients.
"To inform further research and provide solutions to the public health risk of cannabis contaminants at a national level, we examined the current landscape of state-level contaminant regulations and cannabis contaminants of concern, as well as patient populations susceptible to contaminants," proclaimed the study.
About half of all adults in the U.S. "have reported that they have used cannabis at least once in their lives, with nearly 55 million reporting using cannabis within the past year."
The research noted that state-level legalization of marijuana in the United States has "gained significant public interest and support in recent years." It reported that about half of all adults in the U.S. "have reported that they have used cannabis at least once in their lives, with nearly 55 million reporting using cannabis within the past year."
The study's authors explained that cannabis, similar to other agricultural commodities, "is prone to contamination by pesticides, metals, microbes, and mycotoxins. In addition, solvent residues are an increasing concern for cannabis extracts."
The scientists reported that the presence of such contaminants "presents a potential health hazard not only to regular cannabis users and the general public, but also to people with specific health conditions that make them susceptible to harmful contaminants."
The researchers "examined the regulatory documents for medical and recreational cannabis in all legalized U.S. jurisdictions and compiled a complete list of regulated contaminants" that included pesticides, inorganics, solvents, microbes, and mycotoxins.
More specifically, the study data mined "the compliance testing records of 5,654 cured flower and 3,760 extract samples that accounted for approximately six percent of California's legal cannabis production in 2020–2021."
The cannabis samples were obtained from CannaSafe, a "state-licensed cannabis testing laboratory in the Los Angeles area." The samples were submitted by more than 300 cannabis producers and manufacturers in California "for compliance testing between June 2020 and October 2021."
The study surveyed the "contaminant regulation of drug-type Cannabis sativa L. in 50 states and Washington, D.C." and noted that, "as of 18 May 2022, 36 states and Washington, D.C. had legalized medical cannabis and 17 states and Washington, D.C. had legalized both medical and recreational cannabis."
The study's investigation and analysis provides valuable insight into market conditions and potential threats to consumer and patient safety. It reported that California is currently the largest marijuana market in the United States and that "all cannabis and cannabis products in...California are required to be tested for 68 pesticides, four inorganics, 20 solvents, six microbes, and five mycotoxins."
California is currently the largest cannabis market in the United States and that "all cannabis and cannabis products in...California are required to be tested for 68 pesticides, four inorganics, 20 solvents, six microbes, and five mycotoxins."
The research revealed much information of interest to cannabis and hemp industry professionals and entrepreneurs, including the fact that most state medical cannabis programs are run by state-level public health agencies (27 states manage their programs this way). The other 10 programs "were run by departments of commerce, public safety, and others."
The scientists could identify "no apparent difference in regulatory stringency between the medical cannabis programs that were run by public health agencies and those that were not." All 37 jurisdictions published their cannabis regulations on their websites.
"Twenty-three jurisdictions listed specific contaminants in all four categories (i.e., pesticides, inorganics, solvents, and microbes/mycotoxins) in their regulations," noted the study. It also reported that "five jurisdictions did not mention any specific contaminants and one...provided no action levels for its list of contaminants," revealing that regulations regarding cannabis contamination are extremely varied across the country.
The study reported that the naming of chemicals varied considerably from one state to another and that, of the 37 states, "only 16 provided Chemical Abstracts Service Registry Numbers (CASRNs) in their regulatory documents as chemical identifiers" as a means of standardizing their regulatory oversight and enabling comparisons between states.
Large Variability in Regulated Contaminants
The number of regulated contaminants listed by the 36 states and Washington, D.C. was highly variable, reported the research. "Eight jurisdictions provided action levels for only one, two, or three categories of contaminants," noted the scientists. "Most jurisdictions regulated <150 contaminants, whereas a few had significantly longer lists (as a result of the adopted regulations for non-cannabis agricultural products)," they added.
"Most jurisdictions regulated <150 contaminants, whereas a few had significantly longer lists."
Only four states featured more than 400 regulated pesticides, all of which had adopted the full list of U.S. EPA tolerances and exemptions "for pesticide chemical residues in food for their cannabis regulations."
The study reported that 26 jurisdictions featured "curated lists" of contaminants that averaged 81 across all categories. "The miticides bifenazate and etoxazole, the fungicide myclobutanil, and the insecticide imidacloprid were regulated by the highest number of jurisdictions," reported the research.
Concentrates & Solvent Contamination
The study noted that cannabis concentrates "can be contaminated with solvent residues during the manufacturing process" and that the most common regulated solvents found by its investigation were "hexane (25 jurisdictions), heptane (25 jurisdictions), butane (24 jurisdictions), toluene (24 jurisdictions), and benzene (23 jurisdictions)."
"We data mined the compliance testing records of 5,654 flower and 3,760 extract samples in California and identified 141 flower and 423 extract samples containing a detectable level of regulated contaminants," reported the scientists.
"Of the contaminated samples that failed to comply with the state's contamination regulations, 132 were loose-leaf flower and 347 were extracts."
Of the contaminated samples that failed to comply with the state's contamination regulations, 132 were loose-leaf flower and 347 were extracts. "The flower samples contained 39 of the 103 regulated contaminants in California and the extract samples contained 61 of the regulated contaminants," noted the study.
Overall Failure Rates
The study identified an overall failure rate of 5.1 percent for all cannabis samples, "including a 2.3 percent failure rate for flowers and a 9.2 percent failure rate for extracts." It noted that its results were "consistent with the cumulative failure rate of 4.2 percent in all certified cannabis analyses in California's legal market since the inception of the California Department of Cannabis Control (CDCC) in 2017."
The study's authors noted that this failure rate was "consistent with the reported rates from other legal markets in the United States," including Colorado and Oregon.
Interestingly, the study found that microbes, which accounted for under three percent of "all regulated contaminants in the United States," contributed to "most of the reported cannabis contamination outbreaks."
Because 25 of the 34 "legalized jurisdictions" released cannabis use reports between 2016 and 2021, the study was able to include some insightful usage statistics for more than two dozen states for a fairly recent time period.
Patients most commonly consumed cannabis for treatment of pain, followed by Post-traumatic Stress Disorder, "spasticity associated with multiple sclerosis or spinal cord injury, cancer, and epilepsy."
It found that most patient participants in these state programs consumed medical cannabis for treatment and reduction of pain (a total of 799,808 patients), followed by Post-traumatic Stress Disorder (PTSD; 164,383 patients), "spasticity associated with multiple sclerosis or spinal cord injury (78,145 patients), cancer (44,318 patients), and epilepsy (21,195 patients)."
The research also reported that "anorexia, weight loss, and amyotrophic lateral sclerosis had relatively few patients (8,016 and 432 patients, respectively)" and that this result was unexpected "given that both conditions were listed by a large number of jurisdictions as qualifying conditions (25 and 19 jurisdictions, respectively)."
The study observed that 29 percent of the testing samples (nearly one out of three) "were contaminated with ethanol or isopropanol above the acceptable limits."
The researchers concluded that, while marijuana can be and is often employed as a therapeutic agent, "it is not regulated as one in the United States." Their results indicated that slightly more than five percent of cannabis samples that underwent compliance testing "exceeded California's regulatory action levels of contaminants."
While cannabis can be and is often employed as a therapeutic agent, "it is not regulated as one in the United States."
Of equal consequence, the scientists noted that, although batches that fail compliance testing are required, by law, to be removed from the legal market and disposed of, "they are sometimes sold on the underground [legacy] market, which is still thriving in California and the other parts of the United States."
Cannabis Consumption Methods Matter
The study also concluded that its data and analysis reveal "a critical knowledge gap regarding cannabis-borne contaminant exposure with different consumption methods" and noted that combustion and pyrolysis* "of the contaminants may change the associated risk of contamination." Thus, consumers who engage in inhalation via smoking or vaporization may be at higher risk than those using cannabis and hemp products such as edibles, sublingual (under tongue) tinctures, and topicals (creams and lotions).
*According to Merriam-Webster, pyrolysis is a "chemical change brought about by the action of heat."
Contaminants May Worsen Epilepsy
The study summarized that marijuana loose-leaf and other products that contain contaminants may worsen "the progression and prognosis of many qualifying conditions." It found that 73 of the 141 contaminated samples contained insecticides, including chlorpyrifos" and that these insecticides "could target neurotransmitter signaling pathways associated with seizures and epilepsy."
Unified National Regulations Recommended
The study's authors stated that their results demonstrate "an urgent need for a unified regulatory approach to mitigate the public health risk of cannabis contamination at a national level." They said that their opinion is that such guidelines should be based on human health risk assessment methodologies that are "consistent with other agricultural and food commodities."
The study also recommended a "more stringent approach" to contamination regulation due to the additional vulnerabilities of "susceptible patient populations with medical conditions." It said that this should manifest as a "science-based solution to mitigate the health hazards of cannabis contaminants in an expanding U.S. cannabis market."
View the original study.
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