Daily Pot Smokers Court Health Risks
Study Shows Regular Marijuana Users Have Risk of Respiratory Problems and Psychoses
WebMD News Archive
Oct. 15, 2009 -- Marijuana smokers who take up the habit in their teens, as
well as those who smoke daily or nearly every day, are at the greatest risk for
dependence and other ill health effects, according to a new review of marijuana
use worldwide by Australian researchers.
About 9% of those who ever use pot will become dependent, the researchers
But a U.S. expert on the health effects of marijuana says the public health
impact of pot is ''miniscule'' compared to the effects of alcohol. Likewise,
the Australian experts acknowledge that the public health burden of marijuana
is probably modest compared to that of alcohol, tobacco, and other illicit
About one in 25 people ages 15 to 64 have used marijuana worldwide,
according to Wayne Hall, PhD, professor of public health policy in the School
of Population Health, University of Queensland, Brisbane, Australia, and the
co-author of the review published in The Lancet.
''It is an update review [and] was motivated by the collection of better
epidemiological information over the past decade on the health risk of
cannabis," Hall says in an email interview with WebMD.
Hall searched the medical literature for the past 10 years, looking for
studies that focused on adverse health effects of marijuana.
In the U.S., marijuana use peaked in young adults in 1979, then decreased
until the early 1990s, when it again increased before leveling off toward the
end of the 1990s, Hall says.
But marijuana use varies globally, Hall found. ''Trends in use over the past
decade have varied between regions and countries," Hall says. Use has
stabilized or fallen in many developed countries while increasing in some
developing countries, he says.
''The main points of the paper are that evidence has strengthened for the
existence of a dependence syndrome, an increased risk of motor vehicle
accidents if users drive while intoxicated, impaired respiratory function in
daily smokers, psychoses in young people who begin in their mid-teens and use
daily or near daily, and poorer psychosocial outcomes in adolescents who
initiate early and become regular users," Hall tells WebMD.