Marijuana Information

RWU Statement on Marijuana

Rhode Island law currently permits with certain restrictions (e.g. prohibited on any school grounds) the use of marijuana for persons possessing a lawfully issued medical marijuana card. In addition, effective April 1, 2013, Rhode Island law was amended to decriminalize a limited amount (one ounce or less) of marijuana from a misdemeanor to a civil offense for the first and second violations in an 18 month period (the entire statute is available here)

It is important to note, however, that federal law still prohibits the use, possession, distribution, sale or cultivation of marijuana.

The use of marijuana can negatively impact learning, impair clear thinking and mental alertness, and conflicts with the educational mission of Roger Williams University. As an educational institution that receives federal funds, Roger Williams University must comply with federal law under the Drug- Free Schools and Communities Act Amendments of 1989 (20 U.S.C. Section 1011i). Accordingly, the use, possession, distribution, sale or cultivation of marijuana remains prohibited for all students on and off campus via the RWU Student Handbook and the Student Code of Conduct. However, students who possess a lawfully issued medical marijuana card and use marijuana for that purpose in private, off-campus residences will be exempt from University policy in that regard.

FAQs

What is Marijuana?

• Cannabis is derived from the cannabis plant (cannabis sativa).
•  The main active ingredient in cannabis is called delta-9 tetrahydro-cannabinol, commonly known as THC. This is the part of the plant that gives the "high." There is a wide range of THC potency between cannabis products.

Forms of Marijuana?

• Marijuana
  • Marijuana is made from dried flowers and leaves of the cannabis plant.
  • Least potent of all the cannabis products.
  • Usually smoked
• Hashish
  • Hashish is made from the resin (secreted gum) of the cannabis plant.
  • Hashish is dried and pressed into small blocks.
  • Usually smoked but can be eaten.
• Hash oil
  • Hash oil is the most potent.
  • Hash oil is a thick oil obtained from hashish.
  • Smoked

http://adai.uw.edu/marijuana/factsheets/whatiscannabis.htm

What is the difference between American style pot and European style hash?

• The difference between marijuana and hashish goes far beyond country of origin.
  • Marijuana is the most common and least powerful form of cannabis. It is made from dried plant leaves and flowers. Most of American cannabis is strictly the flower or bud of the plant and does not contain whole plants. THC  is the main active ingredient in marijuana that acts upon the nervous system.
  • Marijuana usually contains a maximum of 25% to 30% THC.
• Hashish, also known as hash, is made by eliminating plant material and collecting the trichomes from the flower tops of female cannabis plants. These flowers, or ‘heads’, are the most potent parts of the plant.
• As a result, the THC content of hashish typically varies from 20% to 60%.

http://goaskalice.columbia.edu/difference-between-pot-and-hash

Other names for cannabis?

• Marijuana
• Grass
• Pot
• Weed
• Mary Jane
• Ganga
• Green
• Heads
• Hydro
• Buddha

http://adai.uw.edu/marijuana/factsheets/whatiscannabis.htm

Will Marijuana soothe my feelings of depression and anxiety?

• It can be extremely difficult to feel anxious, depressed, and seemingly unable to make things better. Your desire to find a solution is a great first step, but instead of making you feel better, using pot has the potential to make things worse.  It is unclear as to whether or not pot can cause panic attacks; however, studies have shown that daily marijuana use is correlated with significantly higher levels of depression and anxiety, an increase in suicidal thoughts, and greater risk for schizophrenia later in life.
• Some studies have found that using pot even one time can elevate one's anxiety level, especially during the high.
  • One study found that 22% of marijuana users reported panic attacks. In the same study, women were twice as likely as men to report panic attacks.
• Even if you have a good experience with it, please keep in mind that it is not a long-term solution to your anxiety and could make it worse over time.  Try instead:
  • meditation
  • aerobic exercise
  • yoga/ tai-chi
  • counseling

How long does marijuana stay in the body?

• Puff the magic dragon, Mary Jane, hash, pot, whatever you want to call it, marijuana itself doesn't actually stay in the body. However, some of the chemicals in the drug do, such as THC (delta-9-tetrahydrocannabinol), the substance in pot that's mainly responsible for people's high. Although THC loses its effect on the brain after a few hours, detectable traces may remain in the body for a while longer. THC bonds to fat cells and the stored THC slowly breaks down during metabolism and clears itself from the body. The amount of time this takes varies drastically from person to person and depends on:
  • How much pot is used
  • The method and frequency of use
  • The user's rate of metabolism
  • The concentration of THC in the marijuana plant
• In testing to see if someone has recently used pot, there are two important substances to keep in mind: THC and 9-carboxy-THC. 9-carboxy-THC is a product of the body's metabolism of THC and, more importantly, it's detectable for a longer period of time than THC is detectable. This is the reason that drug tests, namely urine tests, look for 9-carboxy-THC.
  • Typical Periods of Time that Marijuana Use May be Detected:
  • Frequent Users (Frequent users are defined as people who use marijuana several times per week, or more often.)
    • Blood Tests:
      • THC - 4 to 8 hours
      • 9-carboxy-THC - 2 or more weeks
    • Urine Tests:
      • 9-carboxy-THC - 10 to 21 days
      • (The detection period for 9-carboxy-THC in urine may be as long as three months in extremely heavy users.)
  • Infrequent Users (Infrequent users are those who use marijuana seldom enough that THC and/or 9-carboxy-THC are no longer detectable before their next use. In essence, these users do not use pot often enough to allow for the tested substances to build-up from one use to another.)
    • Blood Tests:
      • THC - 3 to 4 hours
      • 9-carboxy-THC - 2 or 3 days
    • Urine Tests:
      • 9-carboxy-THC - 3 to 7 days
  • Research on saliva tests indicated that they may be able to detect THC up to eight hours after ingestion but they aren't widely used. Additionally, exposure to second hand marijuana smoke may result in a positive urine test within one to two days although it's unlikely.

http://goaskalice.columbia.edu/marijuana-how-long-does-it-hang-out-body

Myths v. Facts of Marijuana Use

Myth: Marijuana is not as harmful to your health as tobacco.

• Fact: Although some people think of marijuana as a benign natural herb, the drug actually contains many of the same cancer causing chemicals found in tobacco. Puff for puff, the amount of tar inhaled and the level of carbon monoxide absorbed by those who smoke marijuana, regardless of THC content, are three to five times greater than among tobacco smokers.

https://www.ncjrs.gov/ondcppubs/publications/pdf/marijuana_myths_facts.pdf

Myth: Are vaporizers healthier than smoking marijuana from a pipe, bong, blunt or joint?

• Fact: Marijuana vaporizers work by heating the cannabis to a temperature where active ingredients evaporate into a thin mist. Specifically, the cannabis heats to a temperature of 356 - 392 degrees Fahrenheit, below the point of combustion where smoke is produced. Without combustion, the amount of carcinogens, or toxins, decreases. Depending on the design of the vaporizer, the vapor is then captured in a glass and inhaled via a tube.
• Similar to tobacco, marijuana smoke contains toxins harmful to the respiratory system. Research has shown that regular marijuana smokers have increased rates of respiratory infections. Marijuana vaporizers provide an alternate means of inhaling active cannabinoids, such as delta-9-tetrahydrocannabinol, or THC, while avoiding smoke toxins.
• It's important to know that reliable data to support this technique as less risky to health is limited.

http://goaskalice.columbia.edu/marijuana-certain-methods-smoking-healthier-others

Marijuana Use and Cancer:

• Despite the fact that humans have been growing the marijuana plant for thousands of years, and using it recreationally in the U.S. since the early twentieth century, its effects have not been as thoroughly studied as those of tobacco and cigarette smoking.
• From the studies which have been conducted, we know that incidents of cancer from cigarette smoking are far more numerous than cancers from smoking pot, at least in part because more people smoke cigarettes. Also, even frequent marijuana users tend to consume less than heavy cigarette smokers. One thing to keep in mind, though, is that marijuana smokers usually inhale more deeply and keep the smoke in their lungs for a longer period than tobacco smokers. It is possible that these behaviors increase the lung's exposure to the chemical by-products of smoking. Burning marijuana for smoking releases many substances other than THC, the ingredient which produces the drug's psychoactive effects. THC does not appear to be carcinogenic, but some of the other chemicals released by both marijuana and tobacco smoke are problematic. These include:
  • Tar
  • Carbon monoxide
  • Cyanide.
  • One known carcinogen, benzopyrene, though found in both types of smoke, seems to be greater in pot smoke.
• Another thing to remember, pot is usually not smoked with a filter.  Using one would cut down on the amount of "bad" chemicals entering the body. Some researchers also suggest that inhaling marijuana deep into the lungs and holding it there is something smokers should stop doing. Apparently, this ritualized practice does not significantly increase the drug's effect anyway.
• For now, it does appear that pot smokers may run an increased risk of cancer, as well as bronchial irritation and possibly other health problems. Some recent research found associations between pregnant marijuana smokers and the development of rare leukemias in their young children. However, there has not been enough investigation of this possibility for the link to be clear.

http://goaskalice.columbia.edu/marijuana-does-it-cause-cancer

Myth: Marijuana use is harmless?

• Fact: Short term effects of marijuana use include memory loss, distorted perception, trouble with thinking and problem solving, and anxiety. Students who use marijuana may find it hard to learn, thus jeopardizing their ability to achieve their full potential.
• Study conducted by the National Institute on Drug Abuse (NIDA) found that college students who used marijuana regularly had impaired skills related to attention, memory and learning 24 hours after they last used the drug.
• Another study, conducted by the University of Iowa College of Medicine, found that people who used marijuana frequently (7 or more times weekly for an extended period) showed deficits in mathematical skills and verbal expression, as well as selective impairments in memory-retrieval processes.

https://www.ncjrs.gov/ondcppubs/publications/pdf/marijuana_myths_facts.pdf

Myth: Marijuana is not addictive.

• Fact: It was once believed that marijuana was not addictive; many people still believe this to be true.  Marijuana use, in fact, is often associated with behavior that meets the criteria for substance dependence established by the American Psychiatric Association in the Diagnostic and Statistical Manual of Mental Disorders (DSMIV). Many people use marijuana compulsively even though it interferes with family, school, work, and recreational activities. What makes this all the more disturbing is that marijuana use has been shown to be three times more likely to lead to dependence among adolescents than among adults.

https://www.ncjrs.gov/ondcppubs/publications/pdf/marijuana_myths_facts.pdf

Marijuana: Physical and Psychological Addiction?

• Marijuana is the most widely used illicit drug in the United States (cocaine is second), but scientific understanding about the nature of pot addiction lags far behind research about other drugs. For now, there is no clear-cut diagnosis for marijuana addiction, but mounting evidence from both animal and human studies points to physical and psychological dependence stemming from pot use.
• Smoking marijuana releases THC.  The cannabinoid receptors on nerve cells are concentrated in areas of the brain that influence:
  • pleasure
  • memory
  • concentration
  • sensory
  • time perception
  • coordinated movement
• Heavy pot smokers may quickly build a tolerance to marijuana, possibly needing up to eight times the dose to get the same high as infrequent users. Increased tolerance is a sign of physical dependence and changes in brain chemistry.  THC withdrawals in animals change the activity of nerve cells that house dopamine, a neurotransmitter involved in pleasure, motivation, and reward. Interestingly, all addictive drugs affect dopamine nerve cells in some way.
• OF COURSE, NOT ALL POT SMOKERS BECOME DEPENDENT OF MARIJUANA.
• A study published in the Journal of Psychiatric Research investigated the effects of marijuana use in over 2,000 teens and young adults over four years. Overall, 35 percent of pot smokers showed at least one symptom of dependency such as increased tolerance, withdrawal symptoms, cravings, and continued use despite health problems. Eighty-one percent of high frequency users (defined as using marijuana three or more times a week) had at least one sign of dependency compared to only 22 percent of low frequency users (less than three times a week). Among both groups, the most common sign of dependency was withdrawal.
• A review published in the American Journal of Psychiatry confirms that many (but not all) regular marijuana users experience negative effects when they stop using the drug. Since THC is fat-soluble and lingers in the body, withdrawal symptoms may not be felt immediately. Marijuana withdrawal may not be as severe as quitting alcohol or tobacco.
• Emotional and behavioral withdrawal symptoms may include:
  • irritability
  • restlessness or trouble sleeping
  • fatigue and yawning
  • depressed mood
  • anger and aggression
  • strange dreams
• Physical withdrawal symptoms may include:
  • appetite change
  • nausea or stomach pain
  • weight loss
  • shakiness
  • sweating

Marijuana may not be as addictive as tobacco, alcohol, or other drugs, but there's no question that puffing pot can become a habit. More research is needed to illuminate how and why some folks get high and others get hooked. Meanwhile, marijuana enthusiasts may want to take care not to underestimate the addictive power of pot.

http://goaskalice.columbia.edu/marijuana-addiction

Myth: It's not a big deal if I get caught with marijuana.

• Fact: As a Schedule I controlled substance, marijuana is illegal in the United States.
  • Possession of marijuana or drug paraphernalia for marijuana is considered misdemeanors, and delivery of marijuana or intent to deliver within 1,000 feet of a school (including a university) is a class B felony.  Penalties for these crimes range from a $1,000 fine and 30-days imprisonment for a class B misdemeanor to a $10,000 fine and up to 10 years’ imprisonment for a class B felony.
  • Students caught with marijuana will also be required to go through the university judicial process and will face additional sanctions, which may include removal from on-campus housing. Furthermore, students who have been convicted of possession or sale of a controlled substance, such as marijuana, while receiving financial aid will become ineligible to receive financial aid for at least one year, and possibly indefinitely.

Myth: Marijuana makes you mellow.

• Fact: Research shows that kids who use marijuana weekly are nearly four times more likely than nonusers to report they engage in violent behavior.

https://www.ncjrs.gov/ondcppubs/publications/pdf/marijuana_myths_facts.pdf

Myth: There’s not much parents can do to stop their children from experimenting with marijuana?

• Fact: Many people are surprised to learn that parents are the most powerful influence on their children when it comes to drugs.  By staying involved, knowing what their kids are doing, and setting limits with clear rules and consequences, parents can increase the chances their kids will stay drug free.  The National Household Survey on Drug Abuse, showed that the rate of past-month marijuana use was lower among kids who believed their parents would disapprove.  Parents’ attitudes and actions have a profound influence on their children’s drug-use behavior.

https://www.ncjrs.gov/ondcppubs/publications/pdf/marijuana_myths_facts.pdf

Myth: Driving high is safer than driving drunk?

• Fact: Driving under the influence of marijuana is not safer than driving under the influence of any other intoxicating substance. Habitual marijuana use is strongly associated with car crash injury in general, and this is particularly true when marijuana is used prior to driving.
• Marijuana affects alertness, concentration, perception, coordination and reaction time – essential skills required for safe driving.  Even moderate doses of marijuana have been shown to reduce reaction time, requiring an additional 139 feet to stop a vehicle at highway speeds.

https://mcwell.nd.edu/your-well-being/physical-well-being/drugs/marijuana-or-cannabis-sativa/quitting-marijuana-a-30-day-self-help-guide/myths-and-current-research/ 

Behavioral Signs of Pot Use

• Lack of motivation or ambition for activities that once excited the user.
• In many cases, participation in sports, social groups, or other pursuits will wane or even cease entirely.
• Performance in school or in the workplace will begin to decline, coupled with a sense of apathy towards this decline.
• Withdrawal from the family system – This is most often the case with adolescents and young adults, but can be a warning sign for adults as well.
• Drastic change in peer group – An addict will often abandon peer groups in favor of those who share similar desires and behaviors, namely those engaging in drug use.
• Personal hygiene may begin to suffer as they are less concerned with their public appearance.
• Depressive style of mood. Marijuana addicts manifest many of the same characteristics as those suffering from depression. An addict will have a flat affect and mood; they will appear lazy and day-to-day functioning will start to deteriorate on every major life level.
• Aversive, avoidant behavior

http://www.narconon.org/drug-abuse/signs-symptoms-marijuana-use.html

Immediate Signs of Marijuana Use

The most immediate signs of smoking weed are...

• Dilation of the blood vessels in the eyes (making them bloodshot)
• Increased heart rate
• Increased appetite
• Memory impairment
• Difficulty paying attention or solving problems.

 But the real reason people abuse the drug is for the euphoria that may last three to six hours.

When monitoring for symptoms of weed use, there may be anxiety, fear or panic reactions, especially if they are new to the drug or taking it in an unsettling location. Hallucinations, paranoia and delusional behavior can be symptoms of weed use that is very potent, or consumption of a large amount.

http://www.narconon.org/drug-abuse/signs-symptoms-marijuana-use.html

Physical Signs of Pot Use

Marijuana is a drug of convenience; for a relatively small amount of money (sometimes as little as ten dollars), a person can buy enough that can be shared with several people but still transports easily in a pocket or bag. Furthermore, pot can be purchased in almost any neighborhood in any city or state in the country, thus contributing to the pervasive nature of the drug. It is also considered a drug of convenience because it is easily concealed, both for transport and use. This is why it has become widely popular with adolescents or young adults who have a lot of authority figures involved in their lives. Unlike alcohol, where the signs of use are often overt and overwhelming, a marijuana user can often conceal their use in the event that they are under scrutiny, often with such simple remedies as a quick shower or a few drops of Visine.

However, there are still some physical characteristics that can be used to identify if a loved one is using marijuana, available below:

• Bloodshot eyes
• Slowed speech
• Averting eye contact or an unsteady gaze.

Finally, many people ask about the smell of marijuana and whether or not that can be used as a distinguishing factor. The sense of smell is very personal; one person’s perception of a smell could be dramatically different from a friend or colleague even if they are investigating the same smell. It is recommended that you concentrate on physical symptoms to identify marijuana use than speculating on the fickle nature of smells.

http://www.narconon.org/drug-abuse/signs-symptoms-marijuana-use.html

Identifying Marijuana or Weed Consumption

Marijuana or weed can be consumed as a shredded, dry leafy product or as marijuana oil and resin. These last two are sold under the names "hash" or "hashish." Hash may be found in flat cakes or calls. Hash oil will be amber or brown and may be sold in small glass bottles. When you're looking for signs of weed use, you would be looking for small bags of brownish-green leaves that look like herbs, small chunks of powdery brown substance or very small bottles of brown liquid.

Other signs of weed use are paraphernalia left in a person's room or vehicle. Small pipes, larger complicated water pipes referred to as "bongs," cigarette rolling papers or small ends of smoked hand-rolled cigarettes constitute this sign of weed use.

http://www.narconon.org/drug-abuse/signs-symptoms-marijuana-use.html

Ways to tell if your Child or Someone you know is Using Marijuana:

If you think that your child has been smoking pot, they probably have. These are the big signs:

• Decline in grades
• New friend group
• Stop playing sport/ participating in extracurricular activities
• Change in personality/ disposition (more negative, less approachable).

Don’t ignore these changes, because they are like signs on a very dangerous path.  Grades drop, their ambitions disappear, and their friends change. There are emotional changes too – anger and irritability increase and they often become more paranoid. Depression and suicidal thoughts can also be a by-product of smoking marijuana

http://www.empoweringparents.com/marijuana-drug-addiction-and-teens.php#ixzz2M2JPFzOp

The law is going to change as of April 1, 2013 (S 2253/H 7092 )

Changes to the Penalty for Possession of Marijuana:

• Individuals over the age of 18:
  • Possession of up to an ounce of marijuana for individuals 18 and older will be penalized with a $150 civil offense and forfeiture of the marijuana for the first and secondoffenses within 18 months.
• Individuals under the age of 18:
  • Possession of up to an ounce of marijuana by individuals under 18 will subject these minors to the same civil violation as adults for a first or second offense within 18 months.
  • The minor offender will also be required to attend a drug education course as well as perform community service.
• Failure to provide identification or to honestly give name:
  • Law enforcement may arrest an individual found in possession of up to an ounce of marijuana if they fail to produce picture identification when requested or they fail to honestly provide their name.
• Failure to pay fines:
  • The civil fine will double to $300 if not paid within 30 days of issuance and double again to $600 if it has not been paid within 90 days.
  • Civil violations for marijuana possession will not be grounds for revocation of parole or probation.
• Subsequent offenses:
  •  For all individuals found in possession of up to an ounce of marijuana, a third offense within 18 months could result in a misdemeanor conviction punishable by up to 30 days in jail and/or a fine of up to $500.

https://www.mpp.org/states/rhode-island/ 

Marijuana versus Alcohol: Which is, overall, safer for your body?

Marijuana and alcohol each possesses the potential for unique risks or benefits, so comparing them directly is difficult. 

Alcohol is known to contribute to liver disease, but studies also suggest that a glass of red wine a couple of times per week can help keep your heart healthy. Similarly, marijuana is known to cause short-term cognitive impairment (trouble thinking clearly), but for certain medical conditions, such as glaucoma, marijuana possesses therapeutic properties. However, people using marijuana or alcohol to get high or drunk are more likely to experience the better-known negative consequences of these drugs.

Alcohol use contributes to....

• Memory loss
• Impaired judgment
• Academic, relationship, or work problems
  • Marijuana Use and Academics:
    • Adolescent marijuana users are more likely than non-users to dropout of high school, engage in human immunodeficiency virus risk behaviors and exhibit other forms of delinquency [8–10]. They are also more likely to be arrested [11] and use other illegal drugs such as cocaine, crack and heroine [10, 12, 13]. Adolescent marijuana use also threatens health. The Drug Abuse Warning Network reports that marijuana use was a contributing factor in 110 000 emergency department visits in the United States during 2001 [14]. Approximately 15% of those visits involved adolescents between the ages of 12 and 17 years. In addition, Tashkin [15] reports evidence that long-term abuse of marijuana may have harmful effects on the immune and pulmonary systems and may increase a user's risk of cancer of the head, neck and lungs.
    • Low academic achievers are more likely to be drug users
    • If they receive grades of D or below are more likely than those in good academic standing to have recently used cigarettes, alcohol and/or other illicit drugs.
    • http://her.oxfordjournals.org/content/22/3/372.full
• Long-term impacts:
  • liver disease, heart disease, peptic ulcers, and physical dependency

Marijuana use contributes to...

• Problems thinking clearly
• Memory loss
• Cognitive deficiencies
• Dependency
• If smoked, throat and lung cancer and respiratory problems

Both alcohol and marijuana use are thought to contribute to mental health problems, such as depression and anxiety.  One major difference between marijuana use and alcohol use is that it isn’t possible to ingest a fatal dose of THC, however alcohol poisoning can be fatal.  When comparing safety of alcohol use or marijuana use, these substances may have positive health effects, but heavy use can lead to heavy health risks.

http://goaskalice.columbia.edu/alcohol-vs-marijuana-which-safer

Risky Actions/Decisions: High or Drunk

Getting behind the wheel while drunk or high poses significant risks to you and others. Marijuana and alcohol have both been shown to significantly reduce reaction ability, focus, and motor coordination; skills that are essential to safely operate a motor vehicle. In fact, many activities, such as playing a sport or even riding the subway, become dangerous when drunk or high. In general, being drunk or high compromises sound judgment and may lead to unhealthy or risky decisions that you wouldn't make when sober (like unprotected sex).

• Does the use of marijuana affect a person’s sexual performance?
  • Pot is neither considered a stimulant, nor a depressant, because its effects are in large part determined by the expectations of its users. If you anticipate or hope for a mellow, ride-with-the-tide, go-with-the-flow result from lighting up, that is probably what you will get. If a giggle-fest is your goal, then your tokes may well tickle your fancy. By the same token, marijuana, alcohol, and other drugs can also amplify one's pre-existing personality traits:
    • paranoia
    • fearfulness
    • gregariousness
    • anxiety
    • aggressiveness

            And, these factors don't jump out the window when you jump into bed.

• Making safe and comfortable decisions about sexual behavior might be difficult, and interactions might be filled with a lot of fumbling when using marijuana.  There is no way to predict how pot might influence your sexual relations, or those of anyone else, because of the interplay of individual expectations and differences. However, you and your partner can probably get more specific answers for yourselves by discussing and examining marijuana's role in your sex life. Is smoking pot an innocuous side-bar, used every now and then (legal considerations aside), or is it a third participant on which you depend? For some, sex itself is an anxiety-producing proposition, so they use pot to relax. Others might use weed with the mission of heightening sensitivity. Keeping in mind the powerful role that your mind plays in the action of pot and other drugs, relaxing and getting turned on can happen without bringing drugs into the bedroom. It is possible for a drug to become a crutch for behaviors, sex included. For some, these crutches can turn into necessary aides, resulting in unhealthy use and abuse.
• On a side note....
  • long term use of marijuana does seem to affect reproductive health! Marijuana can impact testosterone production and other hormones.  This can in turn affect fertility, erectile dysfunction, menstruation, and other areas. Also, heavy, long-term marijuana use can either cause or contribute to low motivation and sex drive.

http://goaskalice.columbia.edu/marijuana-and-sex

Marijuana and Driving:

•  Because marijuana impairs one’s ability and slows reaction time, motor skills and visual tracking ability are diminished. Studies have shown that smoking just one marijuana joint reduces reaction time by 41 percent, while two joints reduces it by 63 percent.
•  In 2001, almost 40,000 high school seniors in the United States reported that they got into car accidents while driving high.
• In another study, 33 percent of people pulled over for reckless driving tested positive for marijuana use.
• 18 percent of deaths caused by motor vehicle accidents are due to drug use (which does not include alcohol).
• Driving while high may also not be safe because users usually feel tired and have difficulty concentrating after smoking. Sometimes people experience anxiety and/or visual, perception, and time distortions, none of which would help with navigating a vehicle on a road, or even in the driveway. Also, pot impairs memory formation, so if someone is given directions of where to drive while high, there's a chance that s/he won't quite remember how to get from point A to point B once the trip has begun.

http://goaskalice.columbia.edu/marijuana-and-driving