States where medical marijuana was illegal had higher proportions of non-Hispanic Whites and Blacks/ African-Americans and a slightly higher proportion of college graduates. In this analysis, 8.7% of the sample reported current marijuana use and 23.3% reported current cigarette use. As expected, there was a higher prevalence of current marijuana use in states that have legalized medical marijuana compared to those where medical marijuana was illegal , and this association was stable and significant across age categories, even after adjusting for covariates and applying a Bonferroni’s correction to account for multiple comparisons . Findings indicate an association between statewide legalization of medical marijuana and cigarette and marijuana co-use despite lower cigarette prevalence in states where medical marijuana was legal. Co-use was particularly robust among 18–34 year olds. Overall, cousers were more likely to be nicotine dependent compared to those who did not use marijuana, and 12–17 year old adolescent and 50–64 year old adult co-users were 3-times more likely to have nicotine dependence . These data suggest that medical marijuana legalization could inadvertently affect prevalence of co-use, which is linked to greater nicotine dependence, and the potential to create more barriers to smoking cessation . As more states pass marijuana laws, and the legal marijuana industry is poised to cultivate a landscape of greater access and exposure to marijuana , it is recommended that stakeholders in tobacco control prepare for any unintended effects on tobacco use including the possibility of tobacco initiation/ reinitiation among former smokers and greater nicotine dependence in current smokers . Longitudinal research is needed to evaluate the effect of state marijuana policy on tobacco use and marijuana and tobacco co-use.

Co-use was higher and cigarette prevalence was lower in states where medical marijuana was legal. Given the nationwide increase in co-use ,pipp racks there may be uptake of marijuana use among cigarette users as states, change their marijuana policies and cigarettes smokers gain greater exposure and access to legal marijuana. It is possible that medical marijuana may be providing cigarette smokers with an alternative to tobacco especially as the stigma associated with tobacco continues to rise and the perceived harmfulness of marijuana decreases with legalization . Further, it might be perceived that the effects of marijuana can curb nicotine cravings and withdrawal symptoms to aid in smoking cessation . Finally, alternative tobacco products such as electronic nicotine delivery systems, which are commonly promoted as cessation aids and “safe” alternatives to smoking cigarettes , might also promote use of marijuana and THC oil with vaporizers . Co-use should therefore be monitored over time and examined in response to changes in marijuana policies that will further propel industry promotion of co-use and vaping. As expected, the prevalence of cigarette and marijuana co-use differed according to age. The positive association between medical marijuana legalization and co-use was greatest among 18–34 year olds. Previous studies with adolescents have reported greater prevalence but no increase in marijuana use or changes in permissive attitudes in states where medical marijuana was legal , suggesting that greater marijuana use, and therefore greater co-use, preceded medical marijuana legalization. However, most published studies have focused only on adolescents under the age of 18 years and do not reflect the adult population to which medical marijuana policies apply . Therefore, long-term longitudinal studies are needed to monitor the effects of marijuana legalization, marijuana initiation/ re-initiation, cigarette initiation/ reinitiation, and patterns of co-use across all age categories.

Additionally, it is recommended that such studies take into account statewide variables including number of years since the policy went into effect to adequately capture any measurable changes. These data are needed to explore the growing evidence and public health concerns about the potential “gateway” effect of marijuana on cigarette initiation and nicotine dependence in adolescents and young adults in addition to the potential for re-initiation of cigarettes among former tobacco users. As more states pass marijuana policies, potential increases in co-use could have important treatment implications. Cigarette smokers who also reported current marijuana use were more likely to have nicotine dependence, which is a known predictor of smoking and quitting behavior . The positive link between co-use and nicotine dependence was observed across age categories but these associations differed across measures of dependence . We analyzed both NDSS and TTFC. NDSS scores might have been a better measure of nicotine dependence in our comparison across age groups since the scale addresses five aspects of dependence . In comparison, the TTFC single-item scores might not have captured dependency, particularly in adolescent and young adult populations, who have yet to become regular and established smokers. Other studies have shown problems in using TTFC as a measure of dependence in young adults . Since our analysis included both adolescents and adults, we report both NDSS and TTFC measures of nicotine dependence. In addition, in the present study, cigarette smokers who reported ever but not current marijuana use were at greater risk of having nicotine dependence compared to never marijuana users. This finding supports that the effect of THC exposure on nicotine receptors may be irreversible . Studies are needed to further examine both short term and possibly even the long-term effects of THC and nicotine exposure on nicotine dependence and tobacco cessation. In this analysis, 12–17 year old adolescent and 50–64 year old cigarette and marijuana cousers had the highest odds of having nicotine dependence.

These findings support previous studies linking co-use and nicotine dependence in adolescents and young adults and add to preliminary data that this association was also stable in adults and, surprisingly, particularly robust in 50–64 year old adults. These findings reflect evidence of a U-shaped effect between age and nicotine dependence which peaks at age 50 years due to changes in nicotinic receptors and nicotine-associated metabolism with age , and suggest that this relationship was stable among co-users. Studies are needed to determine the extent to which THC exposure and/or current marijuana use add to this effect . Additionally, 50–64 year olds may represent a unique birth cohort who spent their formative years during the 1960’s and 1970’s with minimal tobacco regulations coupled with a counterculture that promoted marijuana use among a large population . More studies on the Baby Boomer generation, specifically, their perceptions about marijuana, current marijuana use including purpose of use , modality, cigarette co-use, and health outcomes could provide a glimpse into the future as continued legalization will likely influence social norms across the general population . As more states adopt liberal marijuana policies, more studies are needed to understand co-use including the relationship between THC and nicotine in addition to other individual-level factors such as genetics and personality traits that might influence dependence and cessation . We found higher percentages of non-Hispanic Whites and Blacks/ African-Americans in states where medical marijuana was illegal. In this study, these results may be attenuated since our analysis comparing nicotine dependence depended on exclusion of blunt use. The American Civil Liberties Union report data from the NSDUH and Uniform Crime Reporting Data showing that Black males were no more likely to report marijuana use, but 4-times more likely to be incarcerated for marijuana possession compared to their non-Hispanic White male counterparts . Epidemiologic data have shown a linear increase in cigarette and marijuana co-use in Whites, Blacks/ African-Americans, and Hispanics with the fastest rate of increase among Blacks/ African-Americans . Among Blacks/ African-Americans,pipp rack it is possible that statewide legalization of medical marijuana could help to reduce marijuana-related incarcerations, and at the same time, influence the rate of couse. We are cognizant of the many layers that add to the complexities around the issue of marijuana legalization that are well beyond the scope of our study. We recommend future research will assess potential and actual benefits/ costs of marijuana legalization to society at large, and in states where marijuana is legal, identify issues that can be addressed with specific regulatory measures . Study limitations include the cross sectional nature of these analyses which limits our ability to infer causality. Interpretation of our findings is limited to cigarette smokers which is distinct from those who reported other tobacco products . We were unable to examine statewide legalization of medical marijuana by the number of years the policy went into effect using the NSDUH to account for time lags from adoption to full implementation. The NSDUH public dataset only provides a binary categorization of states that were legal vs. illegal that lumps states that just passed the law with long-term legalization states limits our ability to detect long-term effects and may have attenuated our findings. Further study is needed to examine the effect of combusted vs. non-combusted marijuana use on nicotine given increasing prevalence of edible and aerosolized delivery of marijuana with vaporizers . At present, the NSDUH does not ask respondents to indicate whether use was combusted and/ or non-combusted and we recommend that future surveys collect information on marijuana modality to elucidate the relationship between various forms of marijuana intake and nicotine and/ or THC dependence. Data on combusted vs. non-combusted THC intake can also help to identify if there might be differences in health effects across marijuana use modality. In addition, the present study did not examine population density which might be a potential covariate for marijuana use.

Strengths of the study were use of a large national dataset representative of the U.S. population and internal validity of nicotine dependence comparisons across age categories using the same dataset, which eliminates methodological variations from one study to another. Medical marijuana legalization was positively associated with cigarette and marijuana couse and co-users were at greater risk for nicotine dependence. Long-term longitudinal data across age groups are needed to elucidate these results. In the meantime, it is recommended that stakeholders in tobacco control participate in policy discussions involving marijuana legalization including regulatory measures to prevent further co-use and develop novel cessation treatments to help co-users who may have a harder time with quitting.Cannabis is an adaptive and highly successful annual with the ability to grow in most climates across the globe. Cannabis belongs to the Cannabaceae family, “has a life cycle of only three to five months and germinates within six days.”Cannabis can occur in a wild, reproducing state throughout the California floristic provinces, and is cultivated even outside of areas where it may naturally reproduce. Cannabis planting, growing, and harvesting seasons are similar throughout California and typically take place April through October. “Exposed river banks, meadows, and agricultural lands are ideal habitats for Cannabis” since these ecosystems provide “an open sunny environment, light well-drained composted soil, and ample irrigation.” The Cannabis plant has been utilized to produce a diverse set of products with various applications. Today, Cannabis is most commonly produced for its psychoactive properties, though historically it has been used for agricultural production, nutritional value, and industrial purposes. The two species of Cannabis cultivated for psychoactive and physiological effects are Cannabis sativa and Cannabis indica. Marijuana is the most common name referring to varieties of Cannabis produced for mind altering affects. Marijuana contains high levels of chemical cannabinoid compounds including delta-9 tetrahydracannabinol, or THC, the primary psychoactive component of Cannabis. Cannabis has a long history of use in the United States. During the 17th century, the government encouraged hemp production, a fibrous form of Cannabis, for use as rope, clothing, and sails. In the early 20th century after the Mexican Revolution, the recreational use of marijuana was introduced by Mexican immigrants. In 1937, the Marijuana Tax Act was enacted to effectively criminalize marijuana consumption as a result of an anti-marijuana propaganda campaign led by the commissioner of the Federal Bureau of Narcotics, Harry J. Anslinger. During World War II the U.S. Department of Agriculture provided incentives, including draft deferment, for farmers to grow hemp to meet wartime fiber needs. In the 1950s, a series of federal laws were enacted to create mandatory sentencing for people convicted of using drugs classified as illegal, including marijuana. Despite stricter regulation, marijuana was embraced by popular counter-culture movements in the 1960s. This act classified marijuana as a Schedule I controlled substance, the most restrictive schedule of illegal drugs “found by the government to have a high abuse potential, a lack of accepted safety under medical supervision, and no currently accepted medical use.” In fact, the whole Cannabis plant was classified as Schedule I, which means that possession of any portion of the Cannabis plant became illegal under federal law.