| High THC potency and dose uncertainty | THC can impair attention, coordination, and reaction time. The amount delivered can vary with product concentration, device, and how a person uses it. Higher-potency products can make it easier to consume a large dose quickly. | Where THC vapes are legal, rules may require potency disclosure, serving or package limits, and product testing. Other jurisdictions prohibit or tightly control THC products altogether. | Controls aim to reduce accidental overconsumption and make product strength clearer to consumers. Cannabis laws and specific potency limits differ by jurisdiction. |
| Contamination and unregulated ingredients | During the 2019 U.S. EVALI outbreak, the CDC found vitamin E acetate in lung-fluid samples from patients investigated. THC vaping products—particularly those obtained from informal sources—were strongly associated with the outbreak. This finding does not mean that all THC vape products contain vitamin E acetate. | Regulated markets may require licensed production, ingredient restrictions, laboratory testing, and batch tracking. Products from informal or illegal supply chains may not receive these checks. | Controls are intended to reduce exposure to harmful additives and contaminants and to make products traceable if a safety problem arises. |
| Youth access and appeal | Public-health guidance identifies adolescence as a period of ongoing brain development and warns that cannabis use during this stage can affect health and development. Youth access can also be influenced by concealability, product design, and social sources. | Common measures include minimum-age sales rules, age verification, restrictions on marketing and packaging, and penalties for selling to underage people. Requirements vary by market. | These measures seek to limit youth access and reduce the likelihood that vaping products are promoted or sold to minors. |
| Different laws and inconsistent standards | THC is regulated differently across countries and within some countries. A product permitted in one jurisdiction may be prohibited in another, and testing or labeling requirements are not uniform worldwide. | Governments may prohibit THC vape products or permit them only through a licensed, regulated cannabis system with rules for manufacture, sale, labeling, and testing. | Restrictions reflect both public-health concerns and local controlled-substance laws. Legal status should be checked for the specific jurisdiction. |
| Useful public-health references | U.S. Centers for Disease Control and Prevention: E-cigarette, or Vaping, Product Use-Associated Lung Injury (EVALI); CDC: Cannabis and the Developing Brain; CDC: Cannabis and Driving. |