MARIJUANA STUDY FLAWED

The headlines streaming from the recent Journal of the American
Medical Association study on marijuana use and pulmonary function all
suggest that marijuana is safe ("Marijuana doesn't harm lung
function," Web, Jan. 10). Omitted from the calculation is the large
number of marijuana users who believed that they would always be
occasional users but progressed to heavy use.

If the researchers included chronic, heavy marijuana users as part of
the cost of occasional marijuana use, the risks of occasional
marijuana use would have been more complete and served as compelling
evidence for not using marijuana. Consider the estimated 9 percent of
marijuana users who become addicted. That number goes up to 17
percent for users who start at young ages.

This study is comparable to a study on drivers who occasionally speed
and who, over the past 20 years, have had no crashes and no arrests.
The conclusion of such findings would have been that the study found
no evidence that speeding leads to arrest or crashes. This doesn't
make any sense.

Let us not forget the large body of evidence of serious negative
effects of marijuana use, including those related to cognitive and
physical impairment, psychosis and motor vehicle crashes.

ROBERT L. DUPONT

President, Institute for Behavior and Health Inc.

Founding director, National Institute on Drug Abuse

Rockville