Heavy metal contamination is a problem in all areas of the cannabis industry today. In cultivation, in manufacturing and concentrate production, the sector seems plagued with stories of lead contamination. With so many consumers choosing to vape above other methods of ingestion, it's a growing health concern. Despite the increased testing and regulatory oversight, it's still hard to pinpoint the root cause of heavy metals in vape cartridges.

The industry often advertises vaping as a healthier method of consumption. It is popular among younger consumers and patients using cannabis for therapeutic purposes. In many markets, concentrates (including those for vaping) are nearly as popular as flower products. Vaping technology, which was initially adopted from e-cigarette designs, is far from perfect. There are also issues on the cultivation and production side of cannabis. Heavy metals in vape cartridges, including lead, arsenic, and mercury are a growing concern for regulators and consumers.

Over the last year, the US cannabis industry has experienced a wave of contamination scandals, from California to Michigan. Dangerous heavy metals are making their way into concentrates, and eventually into consumers bodies. Even low-level exposure to lead can cause long term and irreversible brain damage, not to mention the carcinogenic or even deadly characteristics of the other heavy metals. The potential fallout from consumer exposure to these elements through vaping is no laughing matter. It's paramount to identify the root cause and control the risk of exposure.

The Spread of Lead in Vaporizers – A Growing Concern for Consumers

The Bureau of Marijuana Regulation (BMR) out of the Department of Licensing and Regulatory Affairs (LARA) in Michigan issued a public health bulletin on April 12, 2019. The announcement urged all state-licensed providers to test for heavy metals in vape cartridges. The notice came after the BMR discovered failed test results within the state's monitoring system. There is a concern that other contaminated products may have escaped notice, and are now in the hands of consumers.

California has also been grappling with lead contamination in cannabis vape cartridges. The most recent problems come from a flood of imported vape cartridges from China. Heavy metal contamination intensified in January 2019, after the Bureau of Cannabis Control (BCC) lowered the threshold to 0.5 micrograms per gram (ug/g). As a point of reference, Washington state has a lead threshold of 1.2 ug/g, and Michigan a limit of 2.0 ug/g in finished products. Suddenly, imported vape products were falling these newly instated limits.

Let's not forget other states who have dealt with their fair share of heavy metal contamination, including Colorado. After reports surfaced in 2014 about fungus, pesticides, and heavy metals contaminating the cannabis supply, the state required better testing protocols. Testing for potency and cannabinoid content was quickly adopted, yet the state has been slow to roll out other mandated testing. Lawmakers are set to look into heavy metals in cannabis this summer.

Each state has a patchwork of legislation concerning heavy metals in cannabis. Some, like Oregon, have no legislation at all. There is also not a standardized approach to testing for heavy metals in vape cartridges. One laboratory may find toxins in cannabis (or the device), while another does not. Without a standard set of protocols, there isn't a coordinated effort to get to the bottom of the issue.

Finding the Source of Heavy Metal Contaminants

Lead, and other heavy metals, are strictly controlled in consumer goods. The days of lead-based paint and household products are long gone. However, as we've seen in the recent wave of bad press, lead is still making its way into cannabis. With a diverse set of regulations across the country, it's hard to get an accurate understanding of where it's all coming from – is it from the soil, the production process, or the device itself?

Cannabis Sativa is a bioaccumulator (also called bioremediator). In the hemp industry, this process is often billed as a positive. Bioremediation is the ability of a plant to remove pollution from its environment. Hemp crops can help pull chemical and heavy metal contaminants from the soil, and it is currently under investigation for how to take advantage of this characteristic.

However, phytoremediation is only positive for products not destined for human consumption. As soon as hemp grown for industrial purposes makes its way into the food chain, there is a high possibility of seeing toxins in those hemp-based products, and THC-rich strains of cannabis as well.  If there is lead or other heavy metals within the environment, its safe to say you'll find it in the mature plant.

Earlier studies have shown that the cannabis plant stores the highest levels of heavy metals within its leaves, which are the parts of the plant used for consumer products. In 1988, a study found worryingly high levels of mercury contamination in cannabis grown in Hawaii's volcanic soil, which is naturally high in the compound. There have been similar findings with other metals.

Beyond soil pollutants, heavy metals may also come from fertilizers and pesticides used during cultivation. Although most regions have detailed regulations on what farmers can and cannot apply to cannabis, the industry is rife with indiscriminate fertilizer usage. Of particular are 'bud bloom' products (phosphate fertilizers) which can contain high levels of arsenic. Rockwool, a common hydroponic growing medium is also of concern. Organic producers should additionally be concerned about contamination coming from animal manure.  

But that's only the beginning. The newest culprit for heavy metal contamination is the vape cartridge. Most cartridges come from China, where lead is commonly mixed with other metals during the manufacturing process. While lead infused metals may not be a concern with most electronics – most electronics don't have a heat component and aren't destined for direct contact with cannabis. As regulators in Michigan and California have seen, somehow the lead is leeching from the vape components and into the concentrate.

Part of the problem is that cannabis is acidic, which means it may naturally pull heavy metals like lead from the surrounding container.  Another possibility exists if the concentrate comes into direct contact with the heating coils — an issue originally outlined by John Hopkins Bloomberg School of Public Health.

The Need for Direction on Heavy Metals

With no international or national rules about heavy metal contamination within the cannabis industry, cultivators, concentrate producers, and device manufacturers are left without clear direction. For example, while California producers prepared for the recent changes to heavy metals in cannabis, the vape cartridges they imported were not. Manufacturers in China were following an entirely different set of rules.

The toxins in cannabis from the cultivation side of the equation are also complicated. Cannabis isn't like other conventional crops. As a phytoremediator, it pulls chemicals from its environment in unique ways, which we are only starting to understand.

Manufacturers need to get a better understanding of how their designs, material, and cannabis concentrates interact over time. If cannabis oil is acidic, how can they redesign the cartridge to prevent heavy metal leaching into the inhaled product?

There also needs to be universal guidelines on testing. Testing an empty cartridge will produce very different results than testing the concentrate within the cartridge. Finally, instead of a patchwork of regulation (or no regulation at all) on heavy metals – the entire cannabis industry needs to follow the same set of laws. Cultivators, producers, manufacturers need to all be on the same page when it comes to heavy metals in vape cartridges.