Pubdate: Thu, 06 Aug 2009
Source: Victoria Times-Colonist (CN BC)
Copyright: 2009 Times Colonist
Author: Amy Minsky, Canwest News Service
Bookmark: (Cannabis)


Marijuana Use Has Been Increasing In Canada As Cigarette Sales Fall

(CNS) - Smoking pot can cause as much damage to cells and DNA as 
tobacco smoke, according to a group of Canadian researchers who are 
challenging the belief that marijuana is less harmful than cigarettes.

Rebecca Maertens, a researcher from Health Canada and co-author of 
the study, says many Canadians believe marijuana smoke is less toxic 
and causes less damage than tobacco because pot is "natural."

Despite several experiments that show marijuana use to have adverse 
health effects, the prevalence of marijuana use in Canada has 
increased over the past decade, while the incidence of tobacco use 
has decreased.

Nearly one quarter of Canadians between the ages of 15 and 24 
reported using marijuana in the previous 12 months according to 2006 
Statistics Canada report. More than 14 per cent of those said they 
used the drug on a daily basis.

The team behind this new study suggested that a lack of understanding 
about the dangers of marijuana plays a part in why youth are so 
cavalier about smoking it.

Neither marijuana nor the main psychoactive component of the plant, 
THC, has been shown to cause cancer.

There are, however, substances in marijuana that are very harmful, 
according to previous studies.

Negative health effects induced by smoking marijuana, such as chronic 
bronchitis, have been well documented, as have other negative health effects.

A 2007 study from New Zealand, for example, examined the effects of 
cannabis on lung capacity. The results suggested that marijuana smoke 
compromised lung efficiency between 2.5 and five times more than tobacco smoke.

Despite some knowledge surrounding marijuana's adverse effects on 
human lungs, researchers still have little knowledge about the 
plant's potential to cause lung cancer, Maertens said.

This is due in part to the difficulty researchers have had in 
identifying and following subjects who have smoked only marijuana.

In the latest study, scientists exposed animal cells and bacteria 
separately to smoke from marijuana and tobacco plants.

Although marijuana smoke caused significantly more damage to cells 
and DNA than tobacco, according to the researchers, only tobacco 
smoke caused chromosome damage.
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