>participants inhaled vaporised cannabis containing 10 mg THC and either

10 milligrams of THC is a relatively low dose, at which few adverse side effects (particularly anxiety/fear) would normally be present.

It's also noticeable in the appendix that the drop-out rate was noticeably higher in the 3:1 (highest CBD level) group. 10 participants in this group left the study, while no more than 3 left from any other group. Four of those were due to "unpleasant drug experience", two to "overintoxication".

I've taken more than 30 milligrams of CBD at a single time and it isn't that strong. Studies trialling CBD for schizophrenia or cancer have pushed the dose to hundreds of milligrams, which starts to show adverse effects but is apparently bearable. The authors don't comment on this peculiarity.