Pubdate: Fri, 29 Aug 2014
Source: Tampa Bay Times (FL)
Copyright: 2014 St. Petersburg Times
Contact: http://www.sptimes.com/letters/
Website: http://www.tampabay.com/
Details: http://www.mapinc.org/media/419
Note: Named the St. Petersburg Times from 1884-2011.
Author: Stephen Nohlgren

POT NOT WITHOUT RISKS

Humans have cultivated marijuana for thousands of years - using fiber 
for cloth, oil for food, smoke for ceremonies and chemicals for medicine.

Scientists know that compounds found in pot can alter physical and 
mental functions, lending credence to sick people who say marijuana 
alleviates their symptoms.

But marijuana - especially in its smoked form - carries risk.

Some studies have linked heavy pot use to heart attacks, mental 
illness and breathing difficulties.

"Marijuana is not a completely benign substance. It is a powerful 
drug with a variety of effects," concluded the Institute of Medicine, 
a neutral research group charged by Congress to study medical marijuana

On Nov. 4, Floridians will vote on legalizing marijuana for medical 
use. Supporters point to sympathetic patients who say they need it.

Possible negative health effects are harder to decipher, because 
studies often conflict. But grounds for caution do exist.

Every medicine carries potentially harmful side effects - listen to 
the warnings at the end of any prescription drug ad on TV.

If marijuana were a prescription drug, it would have undergone the 
gold standard clinical trials that FDA approval requires. Doctors and 
patients could evaluate doses and consider benefit versus risk.

But marijuana is an unregulated herbal remedy. Different strains have 
different chemical content. People smoke it, eat it or take it in 
liquid form. Some users imbibe heavily for years, others just occasionally.

Plus, the federal government dampens research by labeling pot as an 
illegal substance with no medical value.

Still, hundreds of small studies have examined various forms of pot 
in limited fashion, some with potentially negative findings:

Cancer

The National Cancer Institute warns that a few studies suggest that 
marijuana might promote some cancers.

Of particular concern are the carcinogenic tars in smoked pot. They 
are stronger than those in cigarettes. Usage is hard to measure 
because pot smokers inhale less than cigarette users do but hold 
smoke down longer.

So far, few studies have shown elevated risk of lung cancer with pot 
use - once scientists separate out people who also smoke cigarettes.

Kaiser Permanente, a huge west coast HMO, followed 65,000 members for 
an average of eight years and found no increased cancer risk with pot 
use - with one exception: Prostate cancer rose among young pot users, 
though it remained very rare.

The Kaiser study, though reassuring, had its limits. It followed men 
between the ages of 15 and 49 - younger than the ages when many 
cancers typically appear. Many HMO members smoked marijuana only 
occasionally, which might have masked bad outcomes in those who 
smoked more intensely, the Institute of Medicine reported.

"Despite the large cohort size, there might not have been a 
sufficient number of heavy or long-term marijuana users to reveal an 
effect," the report said.

Vaporizing - which uses heat to release useful chemicals without 
burning the plant material - could reduce lung cancer risk, as could 
eating pot, Canada's health agency advised. But to put the lung 
cancer fear completely to rest, the agency said, "further 
well-controlled epidemiological studies are required."

One pot-related malignancy has shown up: The risk of testicular 
cancer in young pot users appears to double from about six cases in 
100,000 users to 12.

Complicating the cancer equation is the possible protective effect of 
cannabis. The National Cancer Institute cited rat and lab dish 
studies where tumors exposed to cannabinoid chemicals failed to 
spread as expected and even shrank. Pot also helped prescription 
drugs work their way into cancerous cells.

In one survey of nine epidemiological studies, the National Cancer 
Institute said, throat cancers seemed to increase among pot smokers 
while tongue cancers decreased.

"Cannabinoids could provide unquestionable advantages compared to 
current antitumoral therapies," the biotechnology branch of the 
National Institutes of Health reports.

Respiratory problems

People who smoke pot daily or almost daily are likely to have 
respiratory problems, similar to those experienced by cigarette 
smokers, the NIH's biotechnology division says.

In one study, heavy marijuana smokers were two to three times more 
likely to suffer from bronchitis than a non user, and five to seven 
times more likely to have a persistent cough.

Evidence is slim that marijuana use -by itself - contributes to 
chronic obstructive pulmonary disease. But a study reported by the 
NIH found that cigarette smokers increase their chances of COPD if 
they also smoke pot.

Heart attack

The heart beats faster during marijuana use and for at least 20 to 30 
minutes afterward.

Blood pressure may decrease at high doses, particularly when users 
stand up, the Institute of Medicine reported. But some studies show 
that pressure can increase when people lie down.

A 2001 study indicated that the chance of a heart attack increases 
300 to 500 percent for about an hour after smoking pot - somewhat 
akin to the stress of vigorous exercise. Other things being equal, 
people who smoke a joint every day will increase their chance of a 
heart attack over the course of a year by 1 to 3 percent, the study 
indicated. That compares to cigarette smoking, which cause up to 30 
percent of heart disease deaths in the United States.

Cardiovascular changes "have not posed a health problem for healthy, 
young users," the Institute of Medicine wrote. "However, such changes 
in heart rate and blood pressure could present a serious problem for 
older patients."

Mental health

Most strains of marijuana are psychoactive - capable of causing 
anxiety, hallucinations and even paranoia, particularly in novices. 
Short-term memory can suffer, as can coordination.

Such symptoms abate after use stops, but studies have raised concerns 
about mental health.

Some users report that pot calms them, yet regular use is associated 
with depression and anxiety in others. People with schizophrenia who 
smoke pot seem to have earlier onset and more frequent episodes.

Marijuana stimulates production of dopamine, a neurotransmitter that 
affects mood. PET scans show heavy use is associated with structural 
changes in the brain. What's less clear is causality. Maybe 
depression and anxiety lead to pot-smoking in some users, rather than 
the reverse.

English researchers recently discovered a gene that makes people more 
likely to have schizophrenia but also more likely to smoke pot - 
offering a new explanation for the link between higher pot use and 
troubling schizophrenia symptoms. Maybe the gene, not pot, is the main culprit.

The Institute of Medicine recommended clinical trials to sort out the 
mental health effects of cannabis -no easy task. Changes in the brain 
"are potentially undesirable in some patients and situations and 
beneficial in others," the institute concluded.

Teenagers

The strongest current evidence about physical, social and 
psychological dangers of marijuana relates to adolescents, whose 
brains are still developing. There is evidence that early pot use can 
alter the brain's pleasure and reward system, making young people 
more susceptible to abuse of opiate-based drugs.

But the relevance of adolescent drug use to a medical marijuana 
debate is unclear. In national surveys, teens report that illegal 
marijuana is easy to acquire, regardless of whether medical use is 
permitted. Several studies have indicated that medical marijuana laws 
do not lead to higher teen use. No significant studies have shown that they do.
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MAP posted-by: Jay Bergstrom