A study done by a group of doctors in Canada at Dalhousie University, concluded that more than 90% of the THC is absorbed into the lungs within the first seconds of inhalation. Another study confirms this, but they put their number at 95% absorption. The 5-15% of THC that isn't absorbed is due to THC loss in trace smoke, or smoke that never enters the lungs.

This doesn't sound right.
According to these reports 90-95% of the THC is absorbed within 3-5 seconds. Now if I were to vaporise a bud and hold the vapor in for 3-5 seconds and then exhale, I get a huge cloud of vapour ( THC, terpines, etc ) expelled from my lungs.
If I hold it for 50 seconds( with vapor you can do this), I get very little coming out when I exhale.
If all the THC is absorbed after 3-5 seconds, then what the hell am I exhaling?

Just because a doctor said it, it doesn't mean it's true.