Vape cartridges, often called “carts,” are pre-filled containers for vaporizing liquids containing active compounds such as nicotine, THC, or CBD. These liquids are mixtures of organic and inorganic compounds that are aerosolized for inhalation. Understanding the specific chemical makeup is important because many substances safe for ingestion can become hazardous when heated and inhaled. This article explores the chemicals found in these products, including their intended base components, additives, contaminants, and thermal byproducts.
Core Ingredients and Base Substances
The foundation of any vape liquid is the active compound dissolved in a carrier or diluent substance. Nicotine products commonly use a base mixture of Propylene Glycol (PG) and Vegetable Glycerin (VG). PG is a thin, colorless liquid that efficiently carries flavor and creates a “throat hit,” while VG is thicker, slightly sweet, and produces dense vapor clouds.
Cannabis vape cartridges typically utilize highly concentrated extracts like THC or CBD distillate, which are naturally very viscous. To ensure proper wicking, manufacturers sometimes add thinning agents to these thick oils, though many quality brands now avoid them. Older formulations sometimes used Medium-Chain Triglycerides (MCT) oil or base components like PG and VG to reduce the oil’s thickness. Full-spectrum oils, which contain a wider range of the plant’s compounds, may not require these additional carrier oils.
Intentional Additives for Flavor and Consistency
Manufacturers frequently introduce chemicals to manipulate the liquid’s properties or enhance the user experience. One substance is Vitamin E Acetate, a thickening agent illicitly used as a cutting agent to dilute expensive THC oil and give it a deceptive appearance of high potency. This oil-based substance was strongly linked to the 2019 outbreak of EVALI because it is toxic to the lungs when heated and inhaled.
Flavoring chemicals are another major category of intentional additives, used extensively in both nicotine and cannabis products. In nicotine vapes, compounds like Diacetyl, which provides a buttery flavor, have been historically used. Although Diacetyl is safe to consume, repeated inhalation links it to ‘popcorn lung,’ a severe, irreversible lung disease called bronchiolitis obliterans. Terpenes are volatile organic compounds often added to cannabis oils to restore flavor lost during extraction or to mimic specific strain profiles, but their safety profile for chronic inhalation remains a concern.
Unintended Contaminants and Hardware Leaching
Beyond the intended ingredients, vape liquids can contain chemicals that are not supposed to be present in the final product. Residual solvents, such as butane, propane, or ethanol, may remain in the oil if they are not fully purged during the cannabis extraction process. The presence of these solvents indicates poor manufacturing practices and inadequate quality control.
Another serious concern is the presence of heavy metals, which can leach into the oil from the heating coil and other cartridge components. These metals can be introduced from low-quality hardware, especially when the device is heated or the liquid is stored for long periods. Examples of heavy metals include:
- Lead.
- Cadmium.
- Arsenic.
- Nickel.
Pesticides used during cultivation can also become highly concentrated in the final oil product. A common fungicide, myclobutanil, is particularly dangerous as it can decompose into hydrogen cyanide, a highly toxic gas, when heated.
Thermal Degradation and New Chemical Formation
The act of vaporization itself, which involves heating the liquid, can create entirely new and hazardous chemical compounds through a process called thermal degradation or pyrolysis. Even the common base substances, Propylene Glycol and Vegetable Glycerin, are subject to this chemical breakdown when heated to high temperatures.
When the heating coil temperature exceeds a certain threshold, the chemical bonds in PG and VG can break down, forming toxic carbonyl compounds. These include formaldehyde, acetaldehyde, and acrolein. Formaldehyde is a known carcinogen, while acrolein is a strong respiratory irritant that can cause irreversible lung damage. The amount of these degradation products varies depending on the device’s wattage, the composition of the e-liquid, and the ratio of PG to VG.
Consumer Safety and Regulatory Testing
To mitigate the risks associated with the complex chemical composition of vape carts, consumers should prioritize products from regulated markets that mandate rigorous third-party testing. Reputable manufacturers provide a Certificate of Analysis (COA) for their products, which details the results of mandatory testing. This documentation confirms the potency of the active ingredients and screens for harmful contaminants.
The COA should specifically confirm the absence of:
- Vitamin E Acetate.
- Residual solvents.
- Pesticides.
- Heavy metals.
Since regulatory oversight varies widely between the nicotine and cannabis markets, consumers should look for transparency regarding the materials used in the cartridge hardware itself. Avoiding black-market or unregulated products is the most effective step to reduce exposure to undisclosed and potentially dangerous chemicals.