POT SMOKE AS DANGEROUS AS TOBACCO: RESEARCHERS

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.