This study evaluated human toxicological and subjective effects after passive (second-hand) exposure to cannabis smoke and concluded
In extreme cases, the effects of passive exposure mimicked active smoking effects though to a lesser extent than in active smokers.
The rapid absorption of THC into blood led to functional pharmacologic effects in nonsmokers as a result of second-hand exposure.
Extreme exposure of nonsmokers could lead to positive drug tests and drug-induced behavioral changes not unlike those produced by active cannabis smoking.
Extreme exposure to second-hand cannabis smoke by nonsmokers led to presence of THC in oral ﬂuid for up to 3 hours after end of exposure.
Indication was found of rapid absorption and metabolism of THC having occurred as a result of second-hand exposure.
Evidence suggests that respiratory and transmucosal absorption were key in linking THC concentration in oral ﬂuid to blood as seen in both nonsmokers and smokers.
Data from the study suggest that second-hand exposure to cannabis smoke should be avoided by nonsmokers and may have implications for those who undergo drug testing and who are engaged in “safety-sensitive activities” (e.g., driving).
Authors: Edward J. Cone, George E. Bigelow, Evan S. Herrmann, John M. Mitchell, Charles LoDico, Ronald Flegel, and Ryan Vandrey