In a recent study published in Preventive Medicine, researchers evaluated the impact of cannabis legalization on pediatric asthma in the United States (US).
Asthma is the most prevalent chronic condition affecting the pediatric population in the US. It is more frequently observed in Hispanic and Black youth, who also disproportionately experience more consequences of related morbidity than White individuals. Cannabis use has been increasing among adults, particularly in states that legalized cannabis.
Recently, a study reported that cannabis use was 11.9% among US parents having minor children in states with recreational cannabis laws (RCL), followed by states with medical cannabis laws (MCL), and the lowest (6.1%) in states without cannabis laws. With the legalization, commercialization, and use of cannabis, exposure to secondhand cannabis smoke (SCS) is likely increasing. Moreover, increased cannabis use by adults may impact pediatric asthma.
About the study
In the present study, researchers analyzed the relationship between cannabis legalization and the prevalence of asthma in US children. Data from the National Survey on Children’s Health (NSCH) were used to estimate the state-level prevalence of pediatric asthma for the 2011-12, 2016-17, and 2018-19 periods.
MCL/RCL adoption was defined as the year when medical/recreational marijuana laws became effective in a state. RCL states were those with MCL and adopted RCL during 2011-18. Established MCL states were those passing MCL before 2011 and had not adopted RCL by 2018, whereas recent MCL states were those that adopted MCL during 2011-18 but lacked RCL by 2018. States without legalization were those lacking RCL/MCL by 2018.
First, the researchers computed weighted estimates by MCL/RCL status. Next, they compared trends in the prevalence of pediatric asthma within MCL/RCL status using paired t-tests. Finally, they applied the difference-in-differences technique to compare the magnitude of change in childhood asthma in RCL/MCL states to those without cannabis legalization.
The sample comprised 227,451 children under 17, with a mean age of 8.56. Nearly 51% were males, 59.6% were non-Hispanic White, 16.7% were Hispanic, 12.3% were non-Hispanic Black, and 11.3% were from other minoritized racial/ethnic groups. Approximately a fifth of children lived in households with income below 100% federal poverty level (FPL) and 7.3% without insurance coverage.
Pediatric asthma prevalence was estimated at 8.9% in 2011-12, 8% in 2016-17, and 7.8% in 2018-19. It declined between 2011-12 and 2016-17 but was stable thereafter. The prevalence of pediatric asthma declined significantly in recent MCL states and those without cannabis legalization relative to 2011-12, with a marginal decrease in established MCL and RCL states.
Notably, asthma prevalence in children increased in RCL states from 2016-17 to 2018-19. Although reductions in asthma prevalence were generally larger in recent MCL states and those without cannabis legalization, the reduction rates did not differ statistically by RCL/MCL status. In RCL, recent MCL, and states without legalization, pediatric asthma prevalence reduced in children aged 0 – 5 compared to 2011-12.
Similarly, significant reductions were noted in recent MCL states and those without legalization among children aged 6 – 11. Of note, asthma prevalence increased in states that legalized cannabis, particularly those with RCL, and this increase was significantly larger in RCL states than in those without legalization.
The decrease in asthma prevalence relative to 2011-12 was significant among males and females in recent and established MCL states and those without legalization. The reductions were marginal in RCL states, but the prevalence of asthma increased in females from 2016-17 to 2018-19. Asthma prevalence decreased significantly among non-Hispanic White children relative to 2011-12 in recent MCL states and those without legalization.
Likewise, reductions were significant among non-Hispanic Black children in states that did not legalize cannabis. Asthma prevalence was slightly higher than during 2011-12 in Hispanic children, regardless of cannabis legalization. In RCL states, asthma prevalence increased in children of all ethnic/racial groups relative to 2016-17.
The authors observed that the overall prevalence of asthma in the pediatric population was no longer declining in recent years (relative to 2016-17). Reductions in asthma prevalence in states without legalization or a post-2011 MCL were evident and more rapid than in RCL states and those with MCL pre-2011, albeit the differences were statistically insignificant by RCL/MCL status.
Notably, asthma prevalence increased in states where cannabis was legalized for recreational use in recent years. Further, asthma prevalence increased in RCL states among children aged 12 – 17 compared to states that have not legalized cannabis. Together, these findings suggested that the legalization of cannabis use might be related to the growing prevalence of asthma, especially in older children and those from minoritized races/ethnicities.