What Do We Know Now About the Impact of the Laws Related to Marijuana?

Objectives: This study presents information on the status and impact of medical and legalized marijuana, and the latest data on attitudes and prevalence of use since implementation of these laws. Recent reports from epidemiologists in Denver and Seattle are summarized to give the readers a sense of the changes as these laws have taken effect in their communities.

Methods: The status of these laws is reviewed and the results of surveys taken before and after the laws were enacted are presented, along with data on changing potency and driving under the influence of marijuana.

Summary: Prevalence of use by youths has not increased, but their negative attitudes towards the risk of using marijuana have decreased, and use by adults has increased. Potency continues to increase, as has the proportion of drivers testing positive for use of the drug. Data from Denver show increases in hospital admissions, emergency department visits, and calls to poison centers, with decreasing arrests and admissions to substance abuse treatment programs. Data from the Seattle area show similar decreases in treatment admissions and police involvement, but also increased prevalence of more frequent use.

Conclusions: Current data suggest that increases in marijuana use preceded legalization in 2012. Treatment admissions were declining before these laws, but some indicators of morbidity seem to be increasing subsequent to legalization, with modest increases in poison center calls in both states and increases in acute medical visits in Denver. Data are needed to understand the relationship between the patterns and amounts of use in terms of consequences, and data on the health conditions of those receiving medical marijuana and the impact of higher potency.