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Q: What are the long-term effects of marijuana?
A: Although all of the long-term effects of marijuana use are not yet known, there are studies showing serious health concerns. For example, a group of scientists in California examined the health status of 450 daily smokers of marijuana, but not tobacco. They found that the marijuana smokers had more sick days and more doctor visits for respiratory problems and other types of illness than did a similar group who did not smoke either substance.
Findings so far show that the regular use of marijuana may play a role in cancer and problems of the immune and respiratory systems.
Cancer
It is hard to find out whether marijuana alone causes cancer, because many people who smoke marijuana also smoke cigarettes and use other drugs. Marijuana smoke contains some of the same cancer-causing compounds as tobacco, sometimes in higher concentrations. Studies show that someone who smokes five joints per day may be taking in as many cancer-causing chemicals as someone who smokes a full pack of cigarettes every day.
Tobacco smoke and marijuana smoke may work together to change the tissues lining the respiratory tract. Marijuana smoking could contribute to early development of head and neck cancer in some people.
Immune system
Our immune system protects the body from many agents that cause disease. It is not certain whether marijuana damages the immune system of people. But both animal and human studies have shown that marijuana impairs the ability of T-cells in the lungs’ immune system to fight off some infections.
Lungs and airways
People who smoke marijuana regularly may develop many of the same breathing problems that tobacco smokers have, such as daily cough and phlegm production, more frequent chest colds, a heightened risk of lung infections, and a greater tendency toward obstructed airways. Marijuana smokers usually inhale more deeply and hold their breath longer, which increases the lungs’ exposure to toxic chemicals and irritants.
Q: What about pregnancy? Will smoking marijuana hurt the baby?
A: Doctors advise pregnant women not to use any drugs because they might harm the growing fetus. Although one animal study has linked marijuana use to loss of the fetus very early in pregnancy, two studies in humans found no association between marijuana use and early pregnancy loss. More research is necessary to fully understand the effects of marijuana use on pregnancy outcomes.
Some scientific studies have found that babies born to women who used marijuana during their pregnancy display altered responses to visual stimulation, increased tremors, and a high-pitched cry, which may indicate problems with nervous system development. During preschool and early school years, marijuana-exposed children have been reported to have more behavioral problems and difficulties with sustained attention and memory than nonexposed children.
Researchers are not certain whether any effects of maternal marijuana use during pregnancy persist as the child grows up; however, because some parts of the brain continue to develop into adolescence, it is also possible that certain kinds of problems will become more evident as the child matures.
Q: What happens if a nursing mother uses marijuana?
A: When a nursing mother uses marijuana, some of the THC is passed to the baby through breast milk. This is a matter for concern, because the THC in the mother’s milk is much more concentrated than that in the mother’s blood. One study has shown that the use of marijuana by a mother during the first month of breastfeeding can impair the infant’s motor development (control of muscle movement). This work has not been replicated, although similar anecdotal reports exist. Further research is needed to determine whether THC transmitted in breast milk has harmful effects on development.
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Marijuana: Facts for Teens (Revised)
La marihuana - Información para los adolescentes (Versión
Revisada)
Marijuana: Facts Parents Need to Know (Revised)
La marihuana: Lo que los padres deben saber (Versión
Revisada)
These publications may be reprinted without permission.
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