As vaporizer cartridges containing cannabis extracts gain in popularity and availability, there are concerns about heavy metal exposure in their use.
A study recently published in Chemical Research in Toxicology has tested 13 American brands, as well as several standard cartridges filled with different extracts. Tests suggest that chromium, copper, nickel, as well as small amounts of manganese, lead and tin can leak over time from the vape material to the vape liquid and then to the aerosol. produced by the vape.
The researchers ultimately believe that the regulatory requirements for heavy metal testing must be reconsidered in order to properly reflect the real risks presented by cannabis vaping products.
Metals found in liquids of commercial vaping products
For this study, the researchers purchased a number of “standard” cartridges and filled them with virgin concentrate, virgin distillate, terpenized concentrate, or terpenized distillate. Thirteen different brands of commercially available THC vaporizers were also purchased. Several of them have been disassembled and crushed into small pieces, in order to be able to assess the elemental composition of typical vaping equipment.
Tests on cannabis extracts were carried out before use as a vaporizer and then again after two-thirds of the liquid had been consumed. In the pre-vaped samples, measurable levels of chromium, copper, and nickel were found, along with small amounts of manganese. However, the levels of the “big four” conventional heavy metals that are routinely tested – arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb) – were all well below regulatory limits.
These same metals were detected in sample extracts after vaping, but in average amounts generally higher than those recorded before vaping.
“The results suggest that the cartridges themselves leach [ndlr : émettent] metals, and potentially at higher rates when the components are heated, ”the scientists warned.
“Since most states and other regulatory bodies typically only require testing for As, Cd, Hg, and Pb, these potential exposure profiles would exceed current regulatory standards. “
Metals can pass from cartridge components to inhaled vapor
The aerosols produced by the commercial cartridges, as well as a model of terpenized distillate and a terpenized concentrate, were also analyzed for the presence of ten different heavy metals: arsenic, cadmium, cobalt, chromium, copper, mercury, manganese, nickel , lead and tin.
Although there is no single, accepted standard method for the analysis of cannabis aerosols, the team at Medicine Creek Analytics recently published an effective method of screening for heavy metals in aerosols, which was also used for this study.
Vaping devices have been roughly sorted into three groups – model systems, commercial vapes with a cartridge design similar to models (“group 1” cartridges), and a third group made up of various material designs (“group 1” cartridges). 2 ”) – and the cannabis extracts in each have been tested by the team.
“Copper, nickel and manganese were detected in all three groups,” the researchers reported. “Chromium was detected in all groups except terpene model systems, and lead was detected in both model systems and group 2 cartridges.”
“The Group 2 cartridges generally had higher concentrations overall, but it is not known whether this is due to the difference between the components of the cartridge, or the battery voltage / temperature inconsistencies. “
To confirm whether the source of this contamination was the leaching of heavy metals from the vape material into the oils and the resulting aerosol, the researchers conducted an additional experiment where six of the model cartridges were filled with non-terpenized model concentrate. Three of them were left in an oven at room temperature and the others in an oven at 42 degrees Celsius to simulate hot conditions, such as the interior of a car. The concentrate contained in these cartridges was removed and tested for heavy metals after three weeks and then after seven months.
Prior to being added to the cartridges, the levels of metals present in the concentrate were all below the limit of detection / limit of quantification values for each metal. After seven months at room temperature, significant amounts of copper and nickel were observed. Cartridges stored at 42 degrees Celsius exhibited even higher levels of these metals, as well as notable levels of lead, tin, chromium and manganese.