Study examines smoking behavior after the implementation of California law

Reviewed by Emily Henderson, B.Sc.Apr 26 2021

Smoking is the leading cause of preventable death in America and causes about 30% of all cancer deaths. That's why researchers with the UC Davis Comprehensive Cancer Center wanted to study the impact of a California law passed in 2016 that raised the tobacco sales age from 18 to 21.

Their new study published in Preventive Medicine examines smoking behavior after the state implemented one of the first tobacco 21 (T21) policies.

The study, conducted by UC Davis researchers Melanie Dove, Susan Stewart and Elisa Tong, looked at smoking patterns before and after the law passed and compared California and other states without a T21 policy. The data was from the 2012-2019 Behavioral Risk Factor Surveillance System.

Most adult tobacco users start smoking cigarettes before the age of 18, when the brain is still developing and is especially susceptible to nicotine and addiction. The new T21 law has the potential, over time, of dramatically reducing the number of youth who begin smoking regularly and that's why it is important to track the impact."

Melanie Dove, Study Lead Author and Assistant Professor, Department of Public Health Sciences, Division of Health Policy and Management, University of California - Davis Health

The study showed that the new T21 law was associated with a greater decrease in smoking, at least when it came to daily smoking, in 18-20-year-olds compared to 21-23-year-olds in California.

"The great news is that the prevalence of 'daily' smoking among 18-20-year-olds went from 2.2% in 2016 to nearly zero in 2019," said Stewart, professor with UC Davis Department of Public Health Sciences, Division of Biostatistics. "A possible reason that we may have seen a decrease in 'daily' smoking, but not 'non-daily' smoking, is that 'daily' smokers are more likely to buy their own cigarettes--so they are more likely to be impacted by sales restrictions."

There was no decrease found in 'non-daily' smoking and that's likely because these users don't smoke regularly and often get cigarettes from a friend or family member. Additionally, there was no associated decrease in 'ever' or 'current' smoking patterns with California's T21 law, at least three years post-implementation.

While it may be surprising that the new T21 law didn't reduce cigarette smoking across all types of smoking behavior, explanations include pre-existing declines in smoking nationwide, enforcement challenges at the state level, increased use of other products (e-cigarettes and marijuana), definitions of smokers in the study, sales outside of retail stores and other tobacco control policies.

"Future studies should examine the role of e-cigarette use, policy enforcement as well as online sales," said Tong, an internist and associate professor who directs tobacco cessation initiatives at the UC Davis Comprehensive Cancer Center.

"These are important public health issues that deserve examination and, potentially, new policy solutions in order to protect our youth in California from the deadly diseases that often result from addiction to tobacco products."