Traversing the triangulum: the intersection of tobacco, legalised marijuana and electronic vaporisers in Denver, Colorado.

OBJECTIVE: To explore the intersection of tobacco, legalised marijuana and electronic vaporiser use among young adults in the 'natural laboratory' of Colorado, the first state with legalised retail marijuana.

METHODS: We conducted semistructured interviews with 32 young adults (18-26 years old) in Denver, Colorado, in 2015 to understand the beliefs and practices related to the use of tobacco, marijuana and vaporisers.

RESULTS: We found ambiguity about whether the phrase 'to smoke' refers to the use of tobacco or marijuana products. Smoking marijuana blunts (emptied cigarillo or tobacco wrap filled with marijuana) was common, but few interpreted this as tobacco use. Marijuana vaporisers were used to circumvent public consumption laws (eg, while at work or when driving). Young adults considered secondhand tobacco smoke dangerous, but perceived secondhand marijuana smoke as benign.

DISCUSSION: Using tobacco products as a delivery method for marijuana (eg, blunts) might be increasing and normalising tobacco use among young adults. Surveillance should explicitly ask about use of tobacco products for marijuana. Marijuana vaporisers, often indistinguishable from nicotine vaporisers, may be used to circumvent public consumption laws; communities concerned about use of marijuana in public spaces should include vaporisers (for nicotine or marijuana) in smoke-free regulations. Tobacco, marijuana and electronic vaporisers should be studied together, rather than separately. This approach is essential in informing research and policy as more US states and countries worldwide move to legalise marijuana.