What the 2019 Vaping-Lung-Injury Outbreak Meant for Cannabis Vape Regulation

The 2019 vaping-lung-injury outbreak changed how regulators viewed cannabis vape products, particularly cartridges sold through illicit channels. In the United States, the outbreak ultimately involved 2,807 hospitalized cases or deaths and 68 confirmed deaths as of February 18, 2020, according to the Centers for Disease Control and Prevention’s final national update.

Investigators did not find that every vaping product posed the same risk. Instead, evidence increasingly pointed to tetrahydrocannabinol (THC) products obtained from informal or illegal sources. A CDC-led study published in the New England Journal of Medicine detected vitamin E acetate in lung-fluid samples from patients with e-cigarette or vaping product use-associated lung injury, or EVALI, but not in samples from a healthy comparison group. The findings strongly associated vitamin E acetate with the outbreak, although researchers noted that other chemicals could have contributed in some cases.

Vitamin E acetate is used in some products as a thickening or diluting agent. It may be safe in certain topical or ingestible applications, but inhaling it is a different exposure route. The outbreak highlighted the danger of using untested additives in products designed to deliver substances directly to the lungs.

Canada faced the same concerns as legal cannabis extracts and vape products began entering the market under the second phase of cannabis legalization. Amendments to the Canadian Cannabis Regulations took effect on October 17, 2019, allowing new classes of cannabis products, including extracts used in vape cartridges. Health Canada subsequently indicated that it was working to better understand the composition of cannabis vaping products and the substances produced when they are heated.

Canadian surveillance also showed why case counts required careful interpretation. A later analysis found that 20 vaping-associated lung-illness cases were reported in Canada between September 2019 and December 2020. Reports involved nicotine, cannabis and other vaping products, and the available information did not establish that every case had the same cause. In its 2020 cannabis adverse-reaction report, Health Canada recorded one suspected case involving a legal cannabis product and two involving undefined cannabis, but none met the agency’s confirmed or probable case definition.

In the United States, the Food and Drug Administration responded to a separate but related concern: youth use of flavored nicotine vaping products. Under its January 2020 enforcement policy, the FDA prioritized action against unauthorized, flavored, cartridge-based e-cigarettes other than tobacco- and menthol-flavored products. The policy focused on nicotine products and was not a blanket ban on cannabis vaping products.

Social-media companies also moved to close a marketing loophole. In December 2019, Instagram announced that branded content promoting vaping, tobacco products and weapons would no longer be permitted. The change was aimed at paid influencer promotions, which had allowed companies to reach audiences through personalities and lifestyle content even when conventional advertising was restricted.

These measures addressed different parts of the problem: contaminated illicit products, youth-oriented nicotine marketing and limited information about the emissions produced by heated cannabis extracts. None, by itself, could guarantee that a vape product was safe. Legal status can improve testing, labeling and accountability, but it does not eliminate the health risks associated with inhaling aerosols or guarantee that long-term effects are fully understood.

For consumers, the clearest lesson from the outbreak was to avoid modifying vape liquids and to be especially cautious with THC cartridges from informal sellers, online dealers or other sources that cannot verify ingredients and manufacturing practices. For regulators and manufacturers, the episode underscored the need for ingredient controls, batch testing, emissions research, transparent labeling and continued monitoring of adverse events.

Health Canada’s continuing work on cannabis product safety, together with the CDC’s findings on EVALI, reflects a broader principle: regulation should be based not only on what is present in a cartridge before use, but also on what the device produces when that material is heated and inhaled.