Drug Policy Letter August / September 1993, p. 26

A recent study concluded that frequent marijuana smokers are
subject to mildly increased health risks. Regular marijuana smokers in the
study visited hospitals slightly more often than non-smokers for
respiratory difficulties, injuries and other reasons. However, the study
failed to prove any correlation between marijuana smoking and significantly
increased health risks.

The study, funded by the Kaiser Foundation Research Institute and
by the National Institute on Drug Abuse, attempted to measure the adverse
health effects of frequent marijuana smoking. It is the first of its kind
to compare the medical histories of a large number of frequent marijuana
smokers who do not smoke tobacco with a demographically similar group of
subjects who do not smoke tobacco or marijuana.

Subjects were selected from patients of the Kaiser Permanente
Medical Care Program in San Francisco and Oakland, Calif., between July
1979 and December 1985. There were 452 self-reported marijuana smokers,
and 450 self-reported non-smokers. Their health was evaluated by hospital
visits classified into three categories: respiratory difficulty, injury
and other. The study found that respiratory visits were significantly
increased for persons who had smoked marijuana for less than ten years, but
not for persons who had smoked longer. The reverse was true for injury
visits among the marijuana smokers. Those people who had smoked marijuana
for longer had an increased number of injury visits. The study concluded
that "the relative risk for the marijuana smoking group compared with the
non-smoking group was elevated but not statistically significant."

Copies of the study are available by contacting Michael R. Pohlen,
Kaiser Permanente Center for Health Research, 3800 N. Kaiser Center Dr.,
Portland, OR, 97227, (503) 335-2400