Tag Archives: vapes

From The Lab

What Cannabis Manufacturers Can Learn from the Pharmaceutical Industry About Trace Metal Impurities in Plastic Materials

By Robert (Rob) Thomas
No Comments

Plastics and polymers are widely used materials in the manufacture of cannabis and hemp consumer products, including vessels, containers, bottles, bags, transfer lines, carts, pods, and other components. However, they are not typically associated with metal contamination of the cannabinoids being produced. By far the most common source of trace-element contamination is heavy metals in the soil, growing medium, or fertilizer. These metals can be taken up through the plant’s root system and ultimately find their way into leaves, shoots and flowers and, finally, into extracted cannabinoids.

A secondary source of metal contamination has also been shown to be from stainless steel vessels, containers and equipment used in the production process. In addition, metal components such as coils, atomizers, tanks, and electrical/battery connections used in vaping cartridges are of particular concern nowadays, as they can leach metal particles into vaping liquids due to manufacturing defects and/or long-term storage of the devices. Some of the metals used include stainless steel, nichrome, brass, solder, and other alloys.

However, it is well documented in the pharmaceutical industry that plastic materials used in manufacturing equipment can potentially contribute to elemental contamination of drug products. The United States Pharmacopeia (USP) has devoted several chapters to this issue.

So, if metal impurities in plastic materials are something the pharmaceutical industry takes seriously, why isn’t this receiving the same attention in the manufacture of cannabis consumer products?

To investigate this question, it is useful to first look at how the pharmaceutical industry approaches the problem—and then examine what evidence exists in the public domain indicating that it could also be an issue for cannabis manufacturers.

 

What Can the Pharmaceutical Industry Teach Cannabis Manufacturers?

Drug products can chemically interact with their associated packaging systems and with the plastic materials and components used during manufacturing, storage, and administration. It is therefore logical that these interactions should not adversely affect either the suitability of the drug product or the packaging system. While suitability for use encompasses many quality attributes, the impact of plastic materials on patient and consumer safety is particularly important.

To address these issues, the United States Pharmacopeia (USP) has developed general chapters covering the quality and suitability of plastic materials used in pharmaceutical applications, including:

  • USP Chapter <661> — Plastic Packaging Systems and Their Materials of Construction Used in Pharmaceutical Manufacturing. [3]
  • USP Chapter <1661> — Evaluation of Plastic Packaging and Manufacturing Systems and Their Materials of Construction With Respect to Their Impact on User Safety.

 

The Potential for Contamination

Pharmaceutical manufacturing involves numerous steps required to convert raw materials into an active pharmaceutical ingredient (API) and ultimately into a drug product. Many of these steps use components that are wholly or partly constructed from plastics or polymers.

These materials can also contain additives such as:

  • antioxidants
  • stabilizers
  • lubricants
  • plasticizers
  • colorants

All of these materials have the potential to contain elemental impurities. It is therefore possible for raw materials, process streams, production intermediates, APIs, and finished drug products to come into contact with plastic components during manufacturing. These interactions can potentially introduce process-related impurities and alter the quality of the pharmaceutical product.

The issue becomes particularly important when plastic vessels are used in liquid storage systems, because the opportunity for interaction between the plastic and the liquid increases.

 

Manufacturers Have a Responsibility

The pharmaceutical industry places the responsibility on manufacturers to establish that plastic components and systems are suitable for their intended use.

This is accomplished through a comprehensive risk-assessment approach in which the materials are appropriately characterized, tested, and evaluated.

Among the criteria considered are:

  • The components should be constructed from well-characterized materials intentionally selected for their intended use.
  • Their general physicochemical properties should be established.
  • Their biological reactivity should be appropriately evaluated.
  • Their safety should be established through appropriate chemical testing, including extractables and leachables profiling, together with toxicological assessment of the results.

The question isn’t simply, “What plastic are we using?” The more important question is: “What can potentially come out of that plastic and enter the product?”

 

How Are Plastic Materials Tested?

Because pharmaceutical manufacturing uses a wide variety of plastic materials and exposes them to many different conditions, there is no single extraction procedure that perfectly represents every manufacturing situation. At the same time, it would be impractical to impose a substantial number of extraction conditions on every manufacturer. The pharmaceutical approach therefore uses a standardized set of extraction conditions designed to assess both organic and inorganic impurities.

USP Chapter <661.3> describes five model extraction methods shown in Table 1.

Table 1: Chemical extraction conditions used to evaluate the suitability of plastic components for the manufacture of drug products or substances.

 

For the assessment of extractable metals, the plastic component is either filled with the test solution, or an appropriate amount of plastic is placed into a high-purity borosilicate flask containing the test solution.

The material is then heated to approximately 55 °C for 96 hours, cooled, and analyzed for relevant metals using ICP-OES or ICP-MS in accordance with USP Chapter <233>.

 

What Metals Are Important?

A well-characterized plastic or polymer should be tested for relevant metals that are known components of the material.

These metals can originate from:

  • starting materials used to manufacture the plastic
  • catalysts and other reagents
  • stabilizers
  • colorants
  • plasticizers
  • other additives

Relevant metals have been identified in compendial and regulatory documents, such as USP Chapter <232> [6] and ICH Q3D guidelines [7], which lists 24 elemental impurities and permitted daily exposure (PDE) limits in micrograms (µg) according to the route of administration and the toxicity of the element as shown in Table 2.

Table 2: USP Chapter 232 and ICH Q3D guidelines permitted daily exposure (PDE) limits for elemental impurities [6,7]. Note: These values are typically based on 10g maximum of the drug product per day, so they should be divided by 10 to calculate the allowable limit in µg/g in the drug product.

The potential significance of a metal depends not only on its concentration but also on how the final product is consumed. For example, the limits for some elements are considerably more restrictive for inhalation products than for orally administered products. [6,7] That distinction is highly relevant to cannabis products, particularly vaping products, where inhalation is the route of exposure.

It’s also important to emphasize that most state-based cannabis regulations in the US only require the monitoring of the  Class 1 “big four” heavy metals (Pb, Cd, As, Hg) to be compliant. This means that if any other metals were present in the cannabis products due to equipment contamination, they would escape scrutiny because there is no requirement to measure them. So, there is clearly a need to expand the elemental panel beyond the  “big four” to ensure consumer safety.

 

What Metal Impurities Are Actually Found in Plastics?

So what metals are actually present in plastics and polymers?

There have been numerous studies investigating toxic metals in plastic materials, although much of this work has focused on laboratory plastics such as flasks, beakers, and tubing. One landmark study was published in Analytical Chemistry in 1977 by John R. Moody and Richard M. Lindstrom.

The researchers evaluated common laboratory container materials and demonstrated that many were unsuitable for trace-metal analysis. For experienced ICP-MS practitioners working at the ultra-trace level, this is hardly surprising. Low-quality plastic laboratory ware can contribute significant contamination, which is why high-purity materials are routinely used when the lowest possible limits of quantitation are required.

Some polymers, including polypropylene and polyethylene, can contain significant concentrations of alkali metals, alkaline-earth elements, transition metals, and other elements, as exemplified in Table 3, which is taken from a study that provides an excellent illustration of the problem. In addition, additives, plasticizers, coloring agents and mold-release agents can introduce additional metals.

Table 3: Trace metals found in common plastic and polymer materials

Other Evidence in the Public Domain

Other studies have investigated toxic-metal concentrations in plastic materials used for food packaging.

Although the results do not necessarily establish that the metals actually leach into food, they provide compelling evidence that a broad range of metallic impurities can be present in plastic and polymer materials.

One particularly relevant study investigated heavy metals and metalloids in various types of plastic bags. The researchers examined polyethylene, HDPE, LDPE, and PVC materials and used closed-vessel microwave digestion followed by ICP-OES analysis.

The results demonstrated that many elemental impurities were present at concentrations in the tens of parts per million, while some elements—including copper, zinc and barium—were present at concentrations exceeding 100 ppm. A subset of this data is shown in Table 4.

The results were not isolated to a single material, as similar findings were obtained from other types of plastic bags.

Table 4: A panel of elemental impurities found in polythene bags (results in mg/kg)

These concentration levels are quite significant. But again, there is an important distinction. The presence of metals in a plastic material does not automatically mean that those metals will migrate into a cannabis product. Without an appropriate extractables study, we do not know the answer to that question.

 

What Does This Mean for the Cannabis and Hemp Industry?

This brings us to the key question. What are the implications for cannabis producers?

The pharmaceutical industry has spent decades developing a comprehensive approach to elemental impurities. The ICH Q3D risk-assessment framework considers potential sources throughout the manufacturing process, including:

  • raw materials
  • manufacturing equipment
  • water
  • container-closure systems
  • drug substances
  • excipients
  • packaging
  • processing steps

Plastic materials therefore become one component of a much larger risk-assessment strategy.

A classic way to visualize this is with a fishbone—or Ishikawa—diagram, designed to identify potential root causes of elemental contamination, as shown in Figure 1.

Figure 1: Classic fishbone diagram of the pharmaceutical manufacturing process to identify the root cause of a problem to better understand elemental impurities in drug products.

 

A Cannabis Elemental-Impurity Risk Assessment

So, the question is, could this approach be adopted by the cannabis industry?  Every stage of the cannabis production process, including cultivation, extraction processing, manufacturing, packaging, and delivery, could potentially contribute elemental contaminants.  And in particular, what plastic components and materials are most likely to be leaching metals when in contact with the multitude of chemicals and solvents used in the extraction process, as well as cannabinoids, terpenes, and diluents used in the formulation of the cannabis consumer products? A proposed fishbone diagram for the cannabis manufacturing process is represented in Figure 2.

Figure 2: Proposed classic risk assessment fishbone diagram for cannabis consumer products

The objective would be to determine which metals could enter the final product at each stage. This approach was proposed in a recent Journal of Testing and Evaluation (JTE) publication that examined the use of a risk-assessment strategy to identify sources of heavy metals in cannabis and hemp products.

The key question is:

Where can the metals come from—and can we demonstrate that each potential source is under control? We know from the published studies that plastic materials can contain measurable concentrations of metals. But what would happen if those same plastic materials were subjected to an extractable metals procedure similar to that used by pharmaceutical manufacturers?

Would the metals actually be released?

 

What Should Cannabis Manufacturers Do?

In today’s disjointed regulatory environment, there is no clear guidance for cannabis producers. However, if a similar situation occurred in a pharmaceutical manufacturing plant, the plant would be expected to investigate the potential source of elemental contamination due to the industry’s regulatory framework and FDA oversight. For cannabis manufacturers, however, there is currently no comparable requirement to conduct such a systematic evaluation.

As a result, a potentially important source of contamination could be escaping scrutiny.

The pharmaceutical approach provides a useful model. Cannabis manufacturers could develop their own risk-based extractables and leachables testing program for plastic components that come into contact with cannabis extracts and finished products.

For example, instead of using extraction conditions developed for pharmaceutical manufacturing, cannabis-specific studies could investigate commonly used cannabis formulations, diluents, solvents, and carriers, including:

  • MCT (medium-chain triglycerides) oil
  • glycerin
  • propylene glycol
  • ethanol
  • terpenes
  • hemp seed oil
  • vegetable oil

Plastic components could be exposed to these materials under controlled conditions and subsequently analyzed for relevant elemental impurities using ICP-MS or ICP-OES. The results could then be incorporated into a broader elemental-impurity risk assessment.

This would allow manufacturers to move from simply asking: “Is this plastic food grade?”….to asking a much more scientifically meaningful question: “Have we demonstrated that this plastic is suitable for its intended use with our cannabis product?”

 

Final Thoughts

With the current state-driven regulatory system, there is very little incentive to fully understand the sources of heavy metals throughout the cannabis production process—or in the final consumer products. And in particular, there is no reason to look beyond the “big four” if state regulators don’t require it. However, there is compelling evidence in the public domain that additional metals could be leaching from plastic materials, particularly when cannabinoid extracts and oils are stored in them for extended periods.

But there has not yet been enough testing to definitively establish the extent of the problem. A suitable leaching procedure could be developed based on approaches already used by pharmaceutical manufacturers. But instead of extraction protocols described in USP Chapter <661>, cannabis-specific protocols could use common diluents used in cannabis formulations to investigate extractable metals from plastic components.

At present, there are no comprehensive state regulations requiring cannabis producers to address this issue. So, until the industry adopts a meaningful risk-assessment approach, we simply don’t know whether plastic materials are a significant source of elemental contamination in cannabis products.

We can only hope that when the industry eventually comes under the scrutiny of federal regulators, we might find out the answer. But until then, we can only keep on asking the questions….and maybe someone is listening!

The Overlooked Risks of Hardware in Pipes, Vapes and Dab Rigs

By Dusty McLean
No Comments

For years, much of the conversation around cannabis quality has focused on what goes into the product: potency, pesticides, solvents, microbial contamination, terpene profiles, and certificates of analysis.

That scrutiny is necessary, but it stops one step too soon.

Cannabis is burned in a pipe, heated inside a vaporizer cartridge, exposed to a high-temperature surface in a dab rig, or otherwise passed through hardware before it reaches the user. That means the materials, manufacturing quality, temperature tolerance, and cleanability of the device also deserve consideration.

We have developed remarkably sophisticated ways to characterize the plant while often overlooking the engineering of the device that heats, holds, or delivers it. That “hardware-blind” approach creates a gap between the chemistry we measure in the laboratory and the actual experience at the point of inhalation.

This is especially relevant as cannabis increasingly moves toward a more sophisticated medical and wellness marketplace. A carefully cultivated and thoroughly tested product can still be undermined by poorly designed or poorly documented hardware. The device affects how heat is applied, how efficiently material is vaporized or combusted, and what additional compounds may enter the inhaled stream. Conversely, appropriate hardware can make the use of a well-characterized product more consistent and controllable. The point is not that technology can rescue unsafe or poor-quality cannabis—it cannot—but that the quality of the plant and the quality of the delivery system are inseparable parts of the same consumer experience.

Consumers therefore need to ask two separate questions:

What is in the cannabis?

And:

What is the cannabis touching before I inhale it?

The answer varies by consumption format.

Pipes and Water Pipes: Material Integrity and Cleanability

Traditional pipes and water pipes are mechanically simple compared with electronic vaporizers, but simple does not mean irrelevant.

Here, the concerns begin with four phases: material composition, heat resistance, surface quality, and sanitation.

A well-made glass device should tolerate the normal temperature changes associated with use without cracking, deforming, or shedding coatings. Consumers should be particularly cautious about mystery materials, painted surfaces in high-heat or smoke-contact areas, poorly finished components, and products for which the manufacturer cannot explain what materials were used.

The issue is not that every inexpensive pipe is inherently dangerous or that every expensive one is inherently safe. Price alone is not a materials specification.

The more useful questions are:

What type of glass or other material is being used? Is decorative material isolated from the smoke path and heated surfaces? Can the product be inspected for damage? Can it be thoroughly cleaned? Are replacement parts appropriately fitted? Does the manufacturer provide meaningful product information?

Water filtration also should not be mistaken for purification.

Research on waterpipe smoking in other inhaled-product categories has demonstrated that passing smoke through water does not eliminate many important smoke toxicants. In one controlled waterpipe study, the bubbler did not significantly reduce carbon monoxide, nitric oxide, polycyclic aromatic hydrocarbons, or dry particulate matter, although it reduced some other constituents. The research involved tobacco rather than cannabis, so it should not be treated as a direct cannabis-risk calculation; instead, it illustrates a broader engineering principle: water filtration is not synonymous with purification.

For reusable cannabis hardware, sanitation creates another practical consideration. Water, resin, and residue accumulate in places consumers may not routinely inspect. A device with complicated internal spaces that cannot be effectively cleaned may be a poor long-term choice regardless of how attractive it looks.

A medical-minded purchasing standard therefore favors known materials, sound construction, inspectability, and cleanability over aesthetics alone.

Vape Hardware: The Device Becomes Part of the Chemistry

Vape cartridges present an entirely different problem.

A cartridge is not merely a container. It is a miniature heating system containing components such as metal alloys, ceramics, seals, electrical contacts, and a heating element, all of which are in close proximity to cannabis oil.

That hardware can matter.

A 2021 study published in Chemical Research in Toxicology analyzed cannabis vaporizer cartridges and their aerosols. Researchers reported that metals, including chromium, copper, and nickel—and smaller amounts of lead, manganese, and tin—could migrate into cannabis oil and the inhaled vapor phase. The researchers concluded that the heating device itself could be a source of metal contamination.

More recent research has reinforced that concern. A 2025 study examining legal Canadian cannabis vape products detected particles containing several metals in vape liquids and found cobalt, chromium, nickel, lead, tin and zinc in aerosols produced from the tested products. Examination of cartridge components provided evidence that device hardware was a source of at least some contamination.

That makes hardware compatibility, component quality, storage stability, and traceable manufacturing especially important in vaping.

Temperature matters as well. Heating conditions influence aerosol chemistry, and higher power is not automatically better simply because it produces more vapor.

There is also an important historical lesson to be learned from the 2019 EVALI outbreak. CDC investigations found vitamin E acetate strongly linked to the outbreak, particularly in THC-containing products obtained through informal sources, while noting that other contributing chemicals could not be completely ruled out. The broader lesson remains relevant: inhalation formulations and hardware should not be treated like ordinary consumer products, and uncertain ingredients or supply chains deserve particular scrutiny.

For patients and other consumers, a professionally manufactured vape product should therefore inspire questions well beyond cannabinoid percentage:

Who manufactured the cartridge?

What materials contact the oil?

Does the hardware supplier document those materials?

Was the final filled product evaluated appropriately?

Are the oil formulation and hardware designed to work together?

Is the product traceable to an accountable manufacturer?

In a mature cannabis market, the cartridge should be considered part of the finished inhalation product—not disposable packaging that escapes scrutiny.

Dab Rigs: Temperature Is the Critical Variable

Dabbing creates yet another risk profile because concentrates are applied directly to a surface that may reach very high temperatures.

Here, the primary engineering issue shifts from cartridge construction toward thermal behavior.

Quartz, ceramic, and titanium components do not behave identically under heat. Their heating and cooling characteristics differ, as do durability, maintenance requirements, and responses to repeated thermal cycling.

But the surface material is only part of the story.

The temperature at which a concentrate is heated can change the chemistry of what is inhaled.

Researchers at Portland State University studying terpene degradation under simulated dabbing conditions identified several thermal degradation products, including methacrolein and benzene. Subsequent research examining gas-phase components from cannabis vaporization and dabbing likewise identified concerning thermal degradation products.

In plain English, heat does more than turn a concentrate into vapor. At sufficiently high temperatures, some naturally occurring compounds in cannabis extracts can chemically break down, forming new compounds. In the laboratory conditions used in this research, those degradation products included methacrolein and benzene. That does not mean every dab produces identical levels of those compounds, but it demonstrates why temperature is not merely a matter of flavor or preference: it can change the chemistry of what is inhaled.

This makes the familiar debate over “hot” versus “low-temperature” dabs more than a matter of flavor preference.

From a product-quality standpoint, a better-designed system is one that gives the consumer predictable, controllable heat rather than simply achieving the highest possible temperature.

That creates another set of questions:

Is the heated component actually made from the material it claims to be?

Is the manufacturer identifiable?

Can the component tolerate repeated heating and cooling?

Is temperature measurable or controllable?

Are consumers given appropriate instructions rather than being encouraged to simply heat the surface as aggressively as possible?

For this category, “medical-grade” should mean more than premium branding. It should suggest known composition, consistency, and an understanding of how the product behaves at its actual operating temperature.

“Medical-Grade” Should Be a Standard of Evidence, Not a Sticker

The cannabis-accessory market has a terminology problem.

There is no universal regulatory certification that makes the phrase “medical-grade” a guarantee of cannabis-hardware quality. Depending on the manufacturer, the term may refer to a particular material specification, an internal quality standard, or little more than marketing language. That is precisely why consumers and retailers should ask what evidence sits behind the label.

Words such as medical-grade, surgical-grade, premium and laboratory-grade can sound reassuring, but a label by itself does not establish safety.

Consumers should ask what the claim actually means.

A meaningful higher-quality standard should include as many of the following as are relevant to the device:

  • clearly identified materials;
  • traceable manufacturing;
  • quality-control documentation;
  • appropriate temperature resistance;
  • product-specific testing;
  • disclosed coatings or finishes;
  • appropriate electrical and battery protections for powered devices;
  • replacement-component compatibility;
  • cleaning and maintenance instructions;
  • accountable manufacturers or distributors;
  • and transparent specifications that can be checked rather than simply advertised.

Responsible retailers have a role here too, and that role begins with educating themselves before attempting to educate the public. We should be able to explain why one device costs more than another without resorting to vague terms like “premium” or simply repeating a manufacturer’s suggested retail price. If the meaningful differences are borosilicate glass, documented materials, improved temperature control, replaceable components, stronger quality assurance, or a legitimate warranty, say so. Those differences matter, and retailers should be able to translate them into plain language for patients and customers.

That does not mean every retailer needs to know everything. Nobody does. Sometimes the honest answer will be, “I don’t know yet.” In a market built on trust, admitting that and finding the answer is more valuable than pretending to have expertise.

Cannabis Product Safety Cannot Stop at the COA

The industry has made enormous progress in teaching consumers to ask for laboratory testing of cannabis itself.

The next step is teaching them to look at the entire delivery system.

A pipe presents questions about material integrity and sanitation.

A vape cartridge introduces a complex interaction between oil, metals, heating elements, storage, and aerosol formation.

A dab rig adds the chemistry of extreme heat and thermal degradation.

These are not interchangeable concerns, and none can be solved by placing the words “medical-grade” on a product page.

The better standard is transparency.

Consumers do not need every retailer to become a materials scientist or toxicologist. They do, however, deserve products whose manufacturers can answer basic questions about what they are made of, how they are intended to be used, and what quality controls are in place behind them.

For an industry working to be taken seriously as both a medical and mainstream consumer market, that should not be an extraordinary expectation.

It should be the baseline.