XPost: alt.politics, alt.politics.republican, alt.politics.democrats   
   From: monkeyhawk@cox.net   
      
   Study Finds No Cancer-Marijuana Connection   
      
   By Marc Kaufman   
   Washington Post Staff Writer   
   Friday, May 26, 2006; A03   
      
      
      
   The largest study of its kind has unexpectedly concluded that smoking   
   marijuana, even regularly and heavily, does not lead to lung cancer.   
      
   The new findings "were against our expectations," said Donald Tashkin of the   
   University of California at Los Angeles, a pulmonologist who has studied   
   marijuana for 30 years.   
      
   "We hypothesized that there would be a positive association between   
   marijuana use and lung cancer, and that the association would be more   
   positive with heavier use," he said. "What we found instead was no   
   association at all, and even a suggestion of some protective effect."   
      
   Federal health and drug enforcement officials have widely used Tashkin's   
   previous work on marijuana to make the case that the drug is dangerous.   
   Tashkin said that while he still believes marijuana is potentially harmful,   
   its cancer-causing effects appear to be of less concern than previously   
   thought.   
      
   Earlier work established that marijuana does contain cancer-causing   
   chemicals as potentially harmful as those in tobacco, he said. However,   
   marijuana also contains the chemical THC, which he said may kill aging cells   
   and keep them from becoming cancerous.   
      
   Tashkin's study, funded by the National Institutes of Health's National   
   Institute on Drug Abuse, involved 1,200 people in Los Angeles who had lung,   
   neck or head cancer and an additional 1,040 people without cancer matched by   
   age, sex and neighborhood.   
      
   They were all asked about their lifetime use of marijuana, tobacco and   
   alcohol. The heaviest marijuana smokers had lighted up more than 22,000   
   times, while moderately heavy usage was defined as smoking 11,000 to 22,000   
   marijuana cigarettes. Tashkin found that even the very heavy marijuana   
   smokers showed no increased incidence of the three cancers studied.   
      
   "This is the largest case-control study ever done, and everyone had to fill   
   out a very extensive questionnaire about marijuana use," he said. "Bias can   
   creep into any research, but we controlled for as many confounding factors   
   as we could, and so I believe these results have real meaning."   
      
   Tashkin's group at the David Geffen School of Medicine at UCLA had   
   hypothesized that marijuana would raise the risk of cancer on the basis of   
   earlier small human studies, lab studies of animals, and the fact that   
   marijuana users inhale more deeply and generally hold smoke in their lungs   
   longer than tobacco smokers -- exposing them to the dangerous chemicals for   
   a longer time. In addition, Tashkin said, previous studies found that   
   marijuana tar has 50 percent higher concentrations of chemicals linked to   
   cancer than tobacco cigarette tar.   
      
   While no association between marijuana smoking and cancer was found, the   
   study findings, presented to the American Thoracic Society International   
   Conference this week, did find a 20-fold increase in lung cancer among   
   people who smoked two or more packs of cigarettes a day.   
      
   The study was limited to people younger than 60 because those older than   
   that were generally not exposed to marijuana in their youth, when it is most   
   often tried.   
      
   --- SoupGate-Win32 v1.05   
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