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Many Cannabis Users Substitute Booze For Pot After Age 21, Study Says

Thursday, 15 March 2012

Many Cannabis Users Substitute Booze For Pot After Age 21Denver, CO: Many adolescent consumers of cannabis increase their use of alcohol and decrease their use of marijuana shortly after turning 21 years of age, according to data published in the Journal of Health Economics.

A team of international investigators from the United States and Mexico estimated the causal effect of legal access to alcohol on marijuana consumption.

They reported: "Our results show that alcohol and marijuana are substitutes. At age 21, we observe a sharp increase in alcohol consumption but a decrease in marijuana consumption. ... Our estimates suggest that the MLDA (minimum legal drinking age) at age 21 decreases the probability of having consumed alcohol in the past 30 days by 16 percent and increases the probability of having consumed marijuana by 10 percent. ... This suggests that policies that restrict access to alcohol cause an increase in marijuana consumption."

Authors stated that this purported substitution effect "is substantially stronger for women than men."

They concluded, "Our results show that legal access to alcohol causes a significant decrease in marijuana use among young adults close to the age of 21."

Separate studies of older cannabis consumers in states with limited legal access to both marijuana and alcohol yield a less consistent trend, with data indicating that many subjects that consume cannabis use reduced levels of alcohol or other intoxicating substances. For example, a 2011 study of qualified medicinal cannabis consumers in California found that respondents' "prevalence of alcohol use was significantly lower" than that of the general population.

Most recently, authors of November 2011 Institute for the Study of Labor paper, "Medical Marijuana Laws, Traffic Fatalities, and Alcohol Consumption," determined: "[The] legalization [of cannabis] is associated with a nearly nine percent decrease in traffic fatalities, most likely due to its impact on [reduced] alcohol consumption."

For more information, please contact Paul Armentano, NORML Deputy Director, at: paul@norml.org. Full text of the study, "The effect of alcohol availability on marijuana use: Evidence from the minimum legal drinking age," appears online in the Journal of Health Economics.