For instance, a 0.45 gram joint of strong herbal cannabis might contain 12.78 standard THC units, while a weaker, seeded herbal cannabis can contain just 3.78 THC units, according to the new estimates.

The study's authors found that to reduce the risk of developing cannabis use disorder, adults should not exceed 8 THC units per week. Seventy percent of the adults who exceeded this limit in the CannTeen study reported cannabis use disorder.

So around the order of magnitude of a joint per week? Well..