What Can Research Tell Us About Today's Cannabis?
Cannabis sold today is far stronger than the cannabis most health studies examined, and the WHO's cancer agency is now evaluating cannabis smoking. What can the evidence actually tell us?
Cannabis has become considerably stronger. In cannabis seized in the United States, average THC content rose from about 4% in 1995 to about 16% in 2022 (NIDA). In the European Union, the average THC content of cannabis resin rose by two thirds between 2014 and 2024 (EUDA). Concentrates sold in legal markets often exceed 60%.
Until 2021, a single licensed grower supplied cannabis for US federal research. When tested in 2017, its cannabis averaged about 5% THC, against about 19% in dispensaries (Vergara et al. 2017). Most population studies record how often people use cannabis, but not how strong it is or how much they take.
In November 2026, a working group convened by the WHO's International Agency for Research on Cancer (IARC) is evaluating whether "cannabis smoking" can cause cancer (IARC). IARC evaluations identify whether something can cause cancer, not how large the risk is at a given level of use. Many people who smoke cannabis also smoke tobacco, which makes the effects of the two hard to separate in studies. Cannabis is also eaten and vaped, and no IARC evaluation of those routes is scheduled.
This SciPoll asks the SciPinion expert community how research on cannabis should be gathered, read and applied as the products themselves have changed. You do not need to specialise in cannabis to answer. The questions are about evidence, and your judgement on evidence is what we are asking for.
All responses are anonymous. Results may be published in aggregate form. No individual responses or identifying information will be included.