Understanding Causes of Cannabis Toxicity
Cannabis plant breeding and cultivation has changed in recent decades. Many plants now contain higher amounts of THC, leading to stronger effects on the brain.1,2,3 Newer methods of consuming cannabis, such as dabbing, vaping, and consuming edibles, may also lead to consumption of higher THC doses.
Among cannabis products, edibles are a common cause of cannabis poisoning, particularly for children and youth who may confuse them for regular food or candy. After legalization, poison control centers experienced an increase in cannabis-related calls (with a high percentage of cannabis exposures being via edibles), particularly involving children ages 0 through 9 years of age.4,5
California regulations limit the amount of THC contained in edible products sold by licensed dispensaries. Edibles products may not exceed 10 mg of THC per serving and may not exceed 100 mg of THC per package.6 However, homemade and black-market edibles may still contain multiple servings of THC. In addition, the physiologic effects from oral consumption are slower in onset and longer in duration compared to inhalation.7 As a result, patients might ingest more cannabis and be affected more strongly and for longer than intended.
Other cannabis products may also increase the risk for toxicity. For example, tinctures, capsules, and topicals are limited by California regulations to a maximum of 1,000 mg of THC per package for non-medicinal use and 2,000 mg per package for medicinal use.6 As a result of these higher THC doses, toxicity with these cannabis products has become a greater concern.
Chemicals and adulterants, particularly in black-market cannabis products, may also be toxic.8 Cannabis users are often unaware of the presence of these chemicals, which may only be identified if the user has a toxicological evaluation as part of a forensic investigation, such as after being arrested for driving while under the influence.9