Text:  Scuba Doc



An article in ‘Alert Diver’ has brought some debate about the side bar containing information about not diving while using marijuana and is based on the following information and references:

To my knowledge, there are no studies on the use of marijuana and diving.

The assumptions that have been made are those that a reasonable person would have to take into consideration when deciding whether or not to dive while taking the drug or when deciding whether or not to allow a person to dive while one is knowingly taking the drug.

"The main active chemical in marijuana is THC (delta-9-tetrahydrocannabinol). In 1988, it was discovered that the membranes of certain nerve cells contain protein receptors that bind THC.

Once securely in place, THC kicks off a series of cellular reactions that ultimately lead to the high that users experience when they smoke marijuana. The short term effects of marijuana use include problems with memory and learning; distorted perception; difficulty in thinking and problem-solving; loss of coordination; and increased heart rate, anxiety, and panic attacks.

Effects of Marijuana on the Brain

Researchers have found that THC changes the way in which sensory information gets into and is processed by the hippocampus. The hippocampus is a component of the brain's limbic system that is crucial for learning, memory, and the integration of sensory experiences with emotions and motivations. Investigations have shown that neurons in the information processing system of the hippocampus and the activity of the nerve fibers in this region are suppressed by THC. In addition, researchers have discovered that learned behaviors, which depend on the hippocampus, also deteriorate via this mechanism.

Recent research findings also indicate that long-term use of marijuana produces changes in the brain similar to those seen after long-term use of other major drugs of abuse.

Effects on the Lungs

Someone who smokes marijuana regularly may have many of the same respiratory problems as tobacco smokers. These individuals may have daily cough and phlegm, symptoms of chronic bronchitis, and more frequent chest colds. Continuing to smoke marijuana can lead to abnormal functioning of lung tissue injured or destroyed by marijuana smoke.

Regardless of the THC content, the amount of tar inhaled by marijuana smokers and the level of carbon monoxide absorbed are three to five times greater than among tobacco smokers. This may be due to the marijuana users’ inhaling more deeply and holding the smoke in the lungs and because marijuana smoke is unfiltered.

Effects on Heart Rate and Blood Pressure

Recent findings indicate that smoking marijuana while shooting up cocaine has the potential to cause severe increases in heart rate and blood pressure. In one study, experienced marijuana and cocaine users were given marijuana alone, cocaine alone, and then a combination of both. Each drug alone produced cardiovascular effects; when they were combined, the effects were greater and lasted longer. The heart rate of the subjects in the study increased 29 beats per minute with marijuana alone and 32 beats per minute with cocaine alone. When the drugs were given together, the heart rate increased by 49 beats per minute, and the increased rate persisted for a longer time. The drugs were given with the subjects sitting quietly. In normal circumstances, an individual may smoke marijuana and inject cocaine and then do something physically stressful that may significantly increase the risk of overloading the cardiovascular system.

Effects of Heavy Marijuana Use on Learning and Social Behavior

A study of college students has shown that critical skills related to attention, memory, and learning are impaired among people who use marijuana heavily, even after discontinuing its use for at least 24 hours. Researchers compared 65 "heavy users," who had smoked marijuana a median of 29 of the past 30 days, and 64 "light users," who had smoked a median of 1 of the past 30 days. After a closely monitored 19- to 24-hour period of abstinence from marijuana and other illicit drugs and alcohol, the undergraduates were given several standard tests measuring aspects of attention, memory, and learning. Compared to the light users, heavy marijuana users made more errors and had more difficulty sustaining attention, shifting attention to meet the demands of changes in the environment, and in registering, processing, and using information. These findings suggest that the greater impairment among heavy users is likely due to an alteration of brain activity produced by marijuana.

Longitudinal research on marijuana use among young people below college age indicates those who used marijuana have lower achievement than the non-users, more acceptance of deviant behavior, more delinquent behavior and aggression, greater rebelliousness, poorer relationships with parents, and more associations with delinquent and drug-using friends.

Research also shows more anger and more regressive behavior (thumb sucking, temper tantrums) in toddlers whose parents use marijuana than among the toddlers of non-using parents."

http://www.nida.nih.gov/Infofax/marijuana.html

Here are some more references:

Babies born to mothers who use marijuana during pregnancy have an eleven-fold increase in nonlymphoblastic leukemia. (Robison LL et al. Cancer 63:1904-1919, 1989)

In males, marijuana diminishes testosterone production and lowers sperm counts. In females, marijuana disrupts hormone cycles. (Gold MS. Marijuana, NY:Plenum Medical Book Co., p. 69-71)

Marijuana contains some of the highest cancer causing substances known. Marijuana contains carbon monoxide, carbon dioxide, acetone, benzene, toluene, vinyl chloride, dimethylnitrosamine, methylethylnitrosamine, benz(a)anthracene, benz(a)pyrene, ammonia, hydrogen cyanide, and many more. (Huber, Gary: Pharm.Biochem.Behavior Vol.40. P.630, 1991. National Academy of Sciences, Institute of Medicine report, Washington DC 1982, Marijuana & Health 1982)

Marijuana smoke produces airway injury, acute and chronic bronchitis, lung inflammation, and decreased pulmonary defences against infection. Smoking one marijuana cigarette leads to airway deposition of four times as much cancer-causing tar as does tobacco smoke. (Tashkin DP. West J Med 158:635-637, 1993)

Cases of cancer, including cancer of the mouth, tongue, larynx, jaw, head, neck, and lungs have been reported in young marijuana smokers. (Donald PJ Otolaryn Head & Neck Surg 94:517-521, 1986. Ferguson RP et al. JAMA 261:41-42, 1989. Taylor FM. South Med J 81:1213-1216, 1988, Donald PJ Adv Exp Med Bio 288:33-46, 1991)

Marijuana causes decreased resistance to diseases such as herpes. (Cabral GA et al. Proc Soc Exp Bio Med 182:181-186, 1986)

In a recent study of blood samples taken from 1441 impaired or dead drivers across Canada, marijuana was found in 38% of the samples. The study underestimates the drug use because in a number of cases, if alcohol were found, drug analyses may not have been done. (K. Wayne Hindmarsh, Dean, Faculty of Pharmacy, University of Manitoba, Wayne K. Jeffery, R.C.M.P. Police Forensic Lab)

Marijuana causes many mental disorders, including acute toxic psychosis, panic attacks, flashbacks, delusions, depersonalization, hallucinations, paranoia, depression and "uncontrollable hostility". (Jenike MA. Drug Abuse. In:Rubinstein E, Federman DD, eds, Scientific American Medicine, NY:Scientific American, Inc., 1993)

A roadside study of reckless drivers not believed to be impaired by alcohol found that 45% tested positive for marijuana. (Brookoff D et al. New Eng J Med 331:518-522, 1994)

Marijuana has long been known to trigger attacks of mental illness, such as bipolar (manic-depressive) psychosis and schizophrenia. It has been shown that marijuana users are six times more likely to develop schizophrenia than are non-users. (Andreasson S et al. Lancet 2:1483-1485, 1987)

Marijuana is a "gateway drug". Children who smoke pot are 85 times more likely to use cocaine than non marijuana users. (Joseph A. Califano, Jr., President of The Centre on Addiction and Substance Abuse)

Marijuana and tobacco comparison. Marijuana and tobacco cause at least the same amount of injury to the airways, pulmonary function, and lung immunity.

US Drug Enforcement Administration

Marijuana

Marijuana Effects on Divers

Some general effects of smoking marijuana:

· The more marijuana is used, the shorter its effects last.

· Tolerance to the psychoactive effects develops with continued use.

· Psychological and mild physical dependence gradually occurs with regular use.

The cannabinoid effect may be additive to nitrogen narcosis.

Carbon monoxide retention leads to high partial pressures of CO at depth - severely reducing oxygenation of red blood cells and tending toward hypoxia on ascent.

Withdrawal symptoms include:

Restlessness, insomnia, nausea, irritability, loss of appetite, sweating.

· Risk of adverse reactions is greater for persons who have had schizophrenia or other psychotic disorder, depression, dysthymia, and bipolar disorder (manic-depression).

· Tar content of marijuana is significantly greater than cigarettes, with more carcinogens.

Risks to diver of cascading events leading to near-drowning or arterial gas embolism.

Potentially harmful effects to divers include:

· Accidents and deaths caused by distortions in perception of time, body image, and distance.

· Impairment of recent memory, confusion, decreased concentration.

· Decreased muscle strength and balance.

· Decreased blood flow in brain.

· Impaired ability to perform complex motor tasks.

· Poor memory.

· Amotivational syndrome.

· Depression, especially in new users.

· 50% of users will have a "bad trip" - severe panic reaction with fear of dying or losing one's mind.

· Fast heart rate and lower exercise tolerance.

· Dry mouth and throat.

High doses may cause:

· Hallucinations

· Depersonalization

· Paranoia

· Agitation

· Extreme panic

Risks to divers -- cascading events leading to drowning and death. Possible injury to buddy and others in dive party.

Chronic use may cause:

· Bronchitis, Sinusitis, Pharyngitis, Chronic cough, Emphysema, Lung cancer. Pulmonary blebs (with barotrauma)

Risk to divers --pulmonary barotrauma, overexpansion injury, arterial gas embolism.

· Poor immune system functioning;

Risk to divers -- severe marine infections.

Poor motivation, depressed mental functioning.

Risk to divers -- errors of omission, commission with cascading events leading to drowning.