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Heavy Metal Contaminants from Cannabis Vaporizer Cartridges: Valid Concern or Blowing Smoke?

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Abstract

Link to the full Emerald Conference 2020 Presentation: https://vimeo.com/442500870 The State of California’s roll out of heavy metal testing on January 1, 2019 sent cannabis vape cartridge manufacturers into a state of panic when many quickly realized that the hardware being used would not pass Phase III compliance testing. In the absence of rigorous study, this spurred a hailstorm of media stories that suggested heavy metal contamination of cannabis vaporizer cartridges poses serious health concerns for the general public. These media scares are potentially damaging for the reputation of cannabis vaporizer cartridges, especially when sample preparations currently being employed are not standardized to evaluate the contribution of the vaporizer cartridge to total metal exposure. In this pilot study, we demonstrate a robust sample analysis method for testing the contribution of a vaporizer cartridge to four toxicant metals (Pb, Hg, Cd, As) in the aerosol consumed by end-users. Three different brands of cartridge hardware using a standardized voltage setting were tested with varying formulations of realistic cannabis formulations to assess how much heavy metal exposure will occur during a cartridge’s lifetime. By testing the cannabis-based formulations in the cartridge, as well as using an air-sampling pump to create realistic cannabis aerosols, we assessed how much of these heavy metals would be aerosolized and thus consumed by an end-user during the normal lifecycle of the cartridge. Our preliminary data suggests that heavy metals do indeed leach from the hardware and a significant portion of these metals end up in the condensate captured.
Heavy Metal Contaminants from Cannabis Vaporizer
Cartridges: Valid Concern or Blowing Smoke?
Kyle Boyar, Vice Chair
Ini Afia, MS Scientific Director
Robert Weltman, MS
Disclaimers & Disclosures
One of the contributing authors is a principal at CannaSafe Analytics, a cannabis
compliance testing laboratory based in Los Angeles, CA.
This work is ongoing with limited sample sizes therefore no final conclusions on
the topic should be derived from the data generated in this pilot study.
Phase 3 Compliance Testing in CA
On January 1, 2019, CA began implementing Phase 3 testing which requires that all
cannabis products be tested for “The Big 4” heavy metals: Arsenic (As), Cadmium (Cd),
Lead (Pb), and Mercury (Hg).
Heavy Metal Action Level for
Medical Edible
Cannabis Products,
Suppositories,
Sublingual Products,
and Other
Manufactured
Products (μg/g)
Action Level for All
Inhaled Medical
Cannabis Goods
(μg/g)
Action Level for
Topical and
Transdermal Medical
Cannabis Goods
(μg/g)
Cadmium 0.5 0.2 5
Lead 0.5 0.5 10
Arsenic 1.5 0.2 3
Mercury 3 0.1 1
Media Field Day
‘Failure’ Results on Hardware:
Variance in Approaches to ‘Compliance’
Without reference methods we saw a wide variety of test results being produced
from different labs.
The Power of Social Media
What prompted our investigations was the sheer number of these articles and
posts from numerous cannabis manufacturers in various compliance and science
groups on platforms such as Facebook.
California – City & County Regulation Watch
Cannabis Science and Chemistry
Approaches for Electronic Nicotine Delivery Systems
Acetaldehyde
Glycerol
Acetyl propionyl (also known as 2,3
-
pentanedione)
Glycidol
Acrolein
Isoamyl acetate
Acrylonitrile
Isobutyl acetate
Benzene
Lead
Benzyl acetate
Menthol
Butyraldehyde
Methyl acetate
Cadmium
N
-butanol
Chromium
Nickel
Crotonaldehyde
Nicotine from any source, including total nicotine, unprotonated nicotine, and nicotine
Diacetyl
salts NNK (4
-(methylnitrosamino)-1-(3-pyridyl)-1-butanone)
Diethylene glycol
NNN (N
-nitrosonornicotine)
Ethyl acetate
Propionic acid
Ethyl acetoacetate
Propylene glycol
Ethylene glycol
Propylene oxide
Formaldehyde
Toluene
Furfural
Questions
1. Does storing cannabinoid-containing solutions in cartridges lead to
appreciable levels of the “The Big 4” heavy metals?
2. If these metals are indeed leaching into the extract, can we quantify the ratio
of ”The Big 4” heavy metals in the pre-vaped cartridge to the post-vape
cartridge and condensed material from vaporization?
3. How does the storage time affect the amount of leaching that occurs during
vaporization?
4. How do the chemical constituents of the solutions affect leaching of heavy
metals?
Experimental Design To answer these questions we
sourced numerous cartridges some of
which were suspected to be
contaminated with heavy metals and
filled them with realistic extract
solutions consisting of THC/CBD
distillate, terpenes, and cutting
agents.
We then ran these cartridges through
a smoking machine and captured the
condensate to test the concentrations
of metals present that would carry
over into the end users lungs.
Diluents and Cutting Agents
TEC Temper by Abstrax Proprietary components
Medium Chain Triglyceride (MCT) Oil
Propylene Glycol (PG)
Vegetable Glycerin (VG)
Polyethylene Glycol (PEG)
Alpha-Tocopherol
Tocopherol Acetate
Viscosity by True Terpenes
Thickener by Floraplex
Terpene Blend Formulation
Terpene formulations with terpenes
sourced from True Terpenes and
Floraplex were utilized to create
cartridges similar to what would be
sourced on the market.
Pictured is a cart formulation
emulating what you would typically
find in a “Durban Poison” type cart.
The Smoking Machine
-Modified aquarium pump
-Arduino (Pump Programming)
-Y connector adaptor
-Aquarium Tubing
-HPLC Tubing
-Vape battery
-Eppendorf tubes
-Parafilm
Arduino Programming & Smoking Machine Protocol
Program the pump to automatically
“inhale” for 12 seconds with thirty
seconds of down time in between puffs.
The battery used had an automatic off
function after 10 seconds of use so
each puff was 10 seconds.
Recover and spin down any remaining
oil in cartridge and recover condensate.
Digest and analyze according to
CannaSafe’s SOP for Heavy Metals
Analysis.
Testing of All Materials Prior to Beginning Work
All test materials were tested according to CannaSafe’s SOP for
Heavy Metals analysis to establish a baseline level of heavy
metals for each formulation.
Sample Preparation & ICP-MS Method
LOD’s and LOQ’s for the analytes tested ranged between 2 – 30 ppb
Five point calibrations from 0–50 ppb were used for each analyte.
Pilot Data
We sourced a batch of cartridges from
a CA manufacturer loaded with oil that
was below action levels. The batch
was suspected to be contaminated by
the hardware used.
When we retested one cartridge from
the same batch six months later: Over
three times the action level for lead
was found.
One Month Post-Filling Data
Note that all carts contained
lead near the CA action levels
after vaping.
Unfortunately for our most
intriguing data point that
exceeded the CA action
limit by 13x there was not
enough condensate
recovered for analysis.
Statistical Analysis (1 Month)
75 As 111 Cd 202 Hg 208 Pb
T-test for pre-vapor to condensate: 0.086 0.635 0.004 0.003
T-test for pre-vapor to remainder no GEM1.2: 0.005 0.281 0.027 0.001
T-test for pre-vapor to post-vapor
(remainder + condensate) no GEM1.2: 0.003 0.468 0.001 0.005
Paired T-test for condensate vs remained: 0.185 0.198 0.217 0.021
Mean Values (1 Month)
75 As [ Conc. Ppb ]
111 Cd [ Conc. Ppb ]
202 Hg [ Conc. Ppb ]
208 Pb [ Conc.
Ppm
]
Pre
-Vapor
4.3
0.6
3.9
0.1
Post
-Vapor
28.0
1.4
10.6
1.1
Post
-Vapor w/o GEM1.2 Cart
24.5
0.8
9.2
0.3
Post
-Vapor Recovered
24.6
0.6
7.9
0.2
Post
-Vapor Remainder
31.4
2.3
13.4
2.0
Post
-Vapor Remainder w/o GEM1.2 Cart
24.3
1.1
11.0
0.454
Ratio of Pre
-Vapor to:
75 As
111 Cd
202 Hg
208 Pb
Post
-Vapor
6.4
2.2
2.7
13.0
Post
-Vapor w/o GEM1.2 Cart
5.6
1.3
2.4
3.7
Post
-Vapor Recovered
5.7
0.9
2.0
2.4
Post
-Vapor Remainder
7.2
3.5
3.5
23.6
Post
-Vapor Remainder w/o GEM1.2 Cart
5.6
1.7
2.9
5.4
75 As
111 Cd
202 Hg
208 Pb
Ratio of Remained to Recovered
1.4
2.0
1.4
2.3
Two Month Post Filling Data
End product data – no vaping performed
All products contained a 2-8 fold increase in lead after two months
75 As [ He ] 111 Cd [ He ] 202 Hg [ He ] 208 Pb [ He ]
Sample Name Vial Number Total Dil. Conc. [ ppb ] Conc. [ ppb ] Conc. [ ppb ] Conc. [ ppb ]
THC Mix 1 (Vaped) 1101 83.3 23.10 5.53 20.98 545.52
THC Mix 1 (Condensate) 1102 100 15.40 5.53 20.57 458.93
CBD Isolate (Vaped) 1103 302.1 61.77 14.20 60.36 727.71
CBD Isolate (Condensate) 1104 194.9 36.79 9.91 36.56 522.04
THC + TEC (Remainder) *1105 72.2 10.23 2.88 10.05 189.61
THC + TEC squared cart (Condensate) 1106 226.2 52.07 15.76 29.27 1887.35
THC + TEC squared cart (Remainder) 1107 38.3 8.91 4.26 1.59 1113.83
75 As [ He ] 111 Cd [ He ] 202 Hg [ He ] 208 Pb [ He ]
Sample Name Vial Number Total Dil. Conc. [ ppb ] Conc. [ ppb ] Conc. [ ppb ] Conc. [ ppb ]
THC + TEC squared cart END Product 1201 59.52 7.99 2.33 2.85 216.74
THC + TEC Gem 1.2 End Product 1202 47.84 9.30 3.32 2.95 831.52
THC Mix 1 C520 End Product 1203 58.48 9.48 2.90 7.39 263.78
CBD Dist + TEC 80/20 Gem 1.2 End Product 1204 67.43 15.99 5.83 8.84 755.04
* = not enough condensate recovered for analysis
Contextualizing the Data
Scenario
Exposure
(
µg/m3
)
Time
Exposed
(Hours/Day)
g) at Mean
Exposure
Amount to Vape (g) at 0.5
PPM To Get Same Exposure
Worker at OSHA Permissible Exposure Limit 50 8266.7 533.3333333
Worker at OSHA Permissible Exposure Limit Action Level 30 8160.0 320
Person who vapes 1 gram a day at 0.5 PPM (0.5 ug / gram) N/A N/A 0.5 1
Person who vapes 10 grams a day at 0.5 PPM (0.5 ug / gram) N/A N/A 5.0 10
Person who vapes 100 grams a day at 0.5 PPM (0.5 ug / gram) N/A N/A 50.0 100
2008 National Ambient Air Quality Standards for Lead 0.15 24 2.4 4.8
Assumptions:
1) From EPA handbook mean inhalation rates are 16.3 to 12.9 m3
per day for adults. 16 m3was taken as a point estimate
2) Breathing rates are constant throughout day
3) "OSHA mandates periodic determination of BLL for those
exposed to air concentrations at or above the action level of 30
µg/m3 for more than 30 days per year."
At our current ambient air quality standards an adult would inhale 4.8 times
as much lead through breathing ambient air than via a 1-gram daily dose
of 0.5 ppm cannabis.
If your job was to smoke cannabis cartridges all day you would need to
vape over 300 cartridges daily to surpass OSHA guidelines that trigger
blood lead testing and would need to vape over 500 cartridges in your 8-
hour shift to surpass the permissible exposure limits.
Study Limitations
1. Potential for intralot variability between the cartridges that were tested
2. Variability between different terpene formulations and cutting agent dilution
ratios in real life scenarios
3. Lack of replicate samples
4. “Realistic vaping”
5. Differences in vaporizer battery settings compared to the ones used in the
study. Our study used an power adjustable E-cigarette battery that was
consistently set to 7.4 W – resistance and voltage were automatically sensed
on the battery and varied from cart to cart.
Future Research and Additional Questions
1. Speciation of heavy metals - organic vs. inorganic
2. Larger sample sizes, intralot variation testing, testing additional terpene
formulations, multifactorial statistical analysis
3. Do other heavy metals leach aside from the Big Four?
4. Testing more cartridges and formulations after variable lengths of time
Conclusions
1. A low cost modified air sampling pump was able to produce condensate
collected in an Eppendorf tube for analysis of heavy metals from cannabinoid-
containing vape cartridge solutions.
2. Recovered and remaining solutions were found to contain elevated
concentrations of heavy metals compared to the starting materials.
3. Even without vaping, cartridges leached more heavy metals with increased
cartridge residence time – some even above CA action levels.
Thank you!
Questions?
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