Other Health Effects
To ascertain the impacts of non-medicinal cannabis use on health, NASEM reviewed epidemiologic studies investigating the associations and risk factors of smoked cannabis and various health conditions. The table below features the key highlights regarding these health effects. Bolded findings had the most significant evidence base for harm.
There are important limitations to these findings. The conclusions are based on epidemiologic studies that show associations but cannot confirm causality. Moreover, these studies generally examined non-medicinal use, which may entail different patterns of use and different levels of THC and CBD compared with medicinal cannabis use. In addition, the findings may not be generalizable to cannabis available for legal purchase today. As smoked cannabis was the only delivery route examined in these studies, these effects may not apply to other forms of cannabis consumption. In addition, it is unknown if and to what degree contaminants contributed to the observed effects. Contaminants in cannabis are prevalent and have poorly understood health effects.32 To address this, for the first time since California legalized medical cannabis in 1996, standards are being implemented for the testing of bacteria, chemicals, pesticides, fertilizers, and heavy metals in cannabis products.33 In California, since January 1, 2018, only those cannabis products that pass testing may be legally sold.34