Marijuana Use and Safe Diving.

[Roger Hobden]

As the use of all forms of recreational marijuana will become legal in Canada two days from now (Wednesday 17 of October 2018), responsible Canadian divers who use this substance will want to know what should be the recommended minimal interval between absorbing this drug and entering the water.

I did a quick search on PubMed today and was quite surprised by the lack of studies that have been published on marijuana usage and scuba diving. Actually, there is virtually nothing out there. So it appears that, for quite a while, health professionals will have to rely on research in other areas and extrapolate to the practice of diving to the best of their knowledge.

One study that just came out today is on the impact of marijuana and driving a motor vehicle. According to that study, one joint will significantly impair driving for at least five hours.

Cannabis use and driving-related performance in young recreational users: a within-subject randomized clinical trial

Given the fact that the drug is absorbed in the fatty tissues of the body and released in the blood stream over a long period, it would make sense to err towards caution.

Based on what is currently known about the underlying physiology, a delay of 24 hours or more might possibly be a prudent course of action. More research will be needed in the future to set firm recommandations, however.

 

[Diving Dubai]

Treat it as you treat alcohol. Neither mix with diving. If you stink of either on my boat you're off, end of converstation and no refund

 

[johndiver999]

Driving is a poor analog because of the impact of nitrogen narcosis. There is an awful lot of diving and smoking dope information out there, but it hasn’t been published.

I would assume that narcosis and thc work synergistically.

 

[JBFG]

I don’t k ow why would you want to take any substance that will impair your judgment as you put yourself in a place where you need all of your judgment.
Terrible idea to me.

 

[scubadada]

Acute use and diving would seem incompatible. I know of no data.

 

[Diver0001]

One study that just came out today is on the impact of marijuana and driving a motor vehicle. According to that study, one joint will significantly impair driving for at least five hours.

I was never a regular user and I don't blow at all anymore but 4-5 hours corresponds to my experience.

Given the fact that the drug is absorbed in the fatty tissues of the body and released in the blood stream over a long period, it would make sense to err towards caution.

This is always a good idea

Based on what is currently known about the underlying physiology, a delay of 24 hours or more might possibly be a prudent course of action. More research will be needed in the future to set firm recommandations, however.

My personal feeling about it is that using any kind of drug or alcohol, if you must do so, should be done after the diving is over and not a moment sooner. If you smoke a joint in the morning, don't dive that day. That's what I would do. YYMV

R..

 

[Doc]

Alcohol has a quantitative measurement, BAC, an accepted, established benchmark. (I.e.: the .08 bogey and it's latest revisionist tightening)

Levels of THC and its relative effect, it's half life, and what effects individual physiology has directly upon duration of such effect- that is comparatively unavailable. This is due in no small part to governmental criminalization limiting funding for studies.

Everything boils down to money.

If there is an insurance claim, the obvious specter of contributory negligence comes into tort liability that will in no small way affect the settlement if a blood or urine test shows presence of alcohol.

This will somehow magically be ignored by insurance companies if someone tests positive for THC?

It's going take a few test cases and some negotiated settlements, but money will, as always, dictate how this is going to end. Insurance companies main objectives: find a reason to disallow coverage, for the claimant and the insured.

Mixing marijuana and any activity besides boinking or eating pizza is demonstrably stupid.

 

[drbill]

I haven't smoked in many years, but there is no way I would and then dive the same day. Likewise for alcohol.

 

[kelemvor]

It's nice that the Canadians are doing the science here since apparently scientists south of the border still can't. I'm sure diving studies will be way way down on the list of things to do when studying the effects of "smoking dope and doing activity x". Extrapolating from studies like the one linked by the OP is far better than options that were available in the recent past.

Since you can detect dope in the urine for like a month (I think?) studies about how long it actually impairs you will likely be critical in combating insurance company copouts. Otherwise, they'll be refusing to pay on their policies if someone smoked 3 weeks ago and then got hurt.

 

[rjack321]

I would assume that narcosis and thc work synergistically.

Based on what? N2 and THC are not acting in even remotely the same way on neural tissues.

Yup, that’s what our police force is saying - 28 days. Police officers are not allowed to work within 28 days after using cannabis. That’s what the initial rule is going to be.

This would be the CYA approach which seems a bit much when you are only talking about personal risk taking not community outrage and litigation.

Those of us in WA and and Oregon have had legal medical and now recreational dope for quite a few years now. At least in the Seattle area there have been no known fatalities associated with pot or edibles and diving. Also very few automobile injuries compared to alcohol. If you are trying to decide personally when to dive after smoking I would suggest 24 to 48 hours based on the half life of THC.​