Recreational marijuana legalization and marijuana and alcohol co-use among adolescents: Differential associations among racial and ethnic groups.

We examined associations of the 2016 legalization of recreational marijuana (RML) in California with marijuana and alcohol co-use among race/ethnic groups using successive cross-sections from 7^th, 9^th, and 11^th graders (N = 3,319,329) in the 2010-11 to 2018-19 California Healthy Kids Surveys. Multilevel logistic regressions indicated a stronger positive association between RML and co-use among non-Hispanic/Latine White youth (OR = 1.21) relative to Hispanic/Latine (OR = 1.02) or Black youth (OR = 0.85). Among drinkers who had not consumed five or more drinks on any occasion in the past 30-days (non-heavy drinkers), the positive association between RML and co-use was stronger among American Indian/Alaska Native youth (OR = 2.19) compared to non-Hispanic/Latine Whites (OR = 1.56). For heavier drinkers it was stronger for Native Hawaiian/Pacific Islanders (OR = 1.47). Among marijuana users, there was a stronger inverse association between RML and co-use among Black youth (OR = 0.72) compared to non-Hispanic/Latine White youth (OR = 0.84). RML may increase the risk of co-use to a greater extent among non-Hispanic/Latine White youth than other race/ethnic groups in California, but broadly increases the risk among youth who engage in alcohol use or heavy drinking.