Cannabis Packaging Can Introduce Heavy Metals Into Vape Products
Testing cannabis only before it is packaged may not reveal every contamination risk. Metals can enter a product from the plant itself, processing equipment, or packaging and vape hardware that remain in contact with the finished material during storage and use.
That concern became more visible after investigations into the 2019 outbreak of e-cigarette, or vaping, product use–associated lung injury. The outbreak was strongly linked to vitamin E acetate in illicit THC-containing products—not established as a heavy-metals event—but it highlighted the need to evaluate the full product, including its container and delivery device. The CDC’s outbreak investigation identified vitamin E acetate as the primary chemical of concern while noting that other toxicants could not initially be ruled out.
Cannabis can take up metals from contaminated soil, water, or growing media. Arsenic, cadmium, lead, and mercury are among the elements commonly monitored because repeated exposure can harm the nervous, kidney, cardiovascular, and respiratory systems. Vape products also raise a separate concern: metal components in cartridges—including heating elements, connector pins, and other hardware—may contribute metals to the oil or aerosol.
In a 2021 in-house packaging leachability study, Modern Canna examined arsenic, cadmium, lead, and mercury in several types of cannabis packaging. The laboratory used MCT oil to simulate cannabis extract in vape cartridges, subjected the cartridges to shaking and repeated heating, and then analyzed the oil with inductively coupled plasma mass spectrometry. The laboratory reported detectable leachable metals in 30% of cartridges supplied by clients and 60% of independently purchased cartridges. It also reported that all pre-roll papers tested contained measurable metals, with an average lead concentration of 527 parts per billion.
Those findings are best treated as an indication of potential risk rather than a population-wide estimate. The evaluation was not a peer-reviewed study, its sample sizes and product selection were limited, and a laboratory leachability protocol does not by itself establish how much metal a consumer would absorb. Still, independent research has provided additional evidence that cartridge hardware can be a source of contamination. A peer-reviewed analysis of cannabis vape liquids found metal particles in unused legal and illicit cartridges, including particles containing copper, zinc, lead, and manganese. The researchers also observed substantial variation between cartridges from the same product lot, which complicates testing and risk assessment.
For laboratories, elemental analysis commonly combines sample preparation with instrumental measurement. EPA Method 3051A describes microwave-assisted acid digestion for materials such as oils and other complex matrices, while EPA Method 6020B describes ICP-MS measurement of multiple elements at very low concentrations. These methods are important technical references, but state and national cannabis programs may specify different analytes, limits, sampling procedures, or validated laboratory methods.
Reliable results also depend on quality control. Laboratories should demonstrate that blanks, calibration checks, reference materials, duplicates, and recovery measurements meet documented acceptance criteria. Results should be reproducible, traceable, and appropriate for the product matrix being tested.
Most importantly, testing should occur after the last step that could introduce or concentrate contaminants. For vape products, that may mean evaluating the filled cartridge—not just the cannabis extract before filling—and considering how the product changes during storage and heating. Packaging suppliers and manufacturers can reduce uncertainty by qualifying cartridge materials, conducting extractables and leachables studies, and screening finished products under realistic storage and use conditions.
Heavy-metal testing cannot eliminate every risk associated with cannabis products, but it can help distinguish contamination originating in the plant from contamination introduced later in manufacturing or packaging. A finished-product approach, supported by validated methods and rigorous quality control, provides a more meaningful assessment of consumer safety than testing the raw cannabis alone.
