Pubdate: Thu, 22 Jun 2000
Source: Albuquerque Tribune (NM)
Copyright: 2000 The Albuquerque Tribune.
Author: Andre Picard, Scripps Howard News Service


Smoking marijuana puts you at greater risk of lung cancer than smoking
tobacco, according to a California study.

That's because the same ingredient that makes marijuana smokers high breaks
down their body's ability to fight off tumors.

In the Journal of Immunology, researchers report that tetrahydrocannabinol
(THC), the major psychoactive component of marijuana, may even promote the
growth of tumors.

Steven Dubinett, head of Jonsson Cancer Center at the University of
California at Los Angeles, said that experiments on mice demonstrated that
THC reduces the body's ability to produce cytokines, powerful immune
suppressors that are known to limit tumor growth.

Previous research has shown that THC can also lower resistance to both
bacterial and viral infections.

The principal reason marijuana smoking raises the risk of lung cancer is
that marijuana smoke contains a lot more tar than does tobacco smoke.

A marijuana cigarette also contains higher concentrations of carcinogenic
hydrocarbons than a regular cigarette. And marijuana smoke deposits four
times as much tar in the respiratory tract as does a comparable amount of
tobacco, according to the research.

All told, smoking three marijuana cigarettes is equivalent to smoking a
pack of unfiltered cigarettes.

"What we already know about marijuana smoke, coupled with our new finding
that THC may encourage tumor growth, suggests that regular use of marijuana
may increase the risk of respiratory-tract cancer," Dubinett said.
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