A committee of US experts estimated the likely reduction in tobacco-use initiation that would be achieved by raising the minimum age of legal access (MLA) to tobacco products to 19, 21 or 25 years old.
Researchers used two tobacco-use simulation models to quantify the accompanying public health outcomes.
Raising the MLA to age 21 likely will have a substantially greater impact on reducing the initiation of tobacco use - defined as having smoked 100 cigarettes - than raising it to 19, researchers said.
Underage users rely primarily on social sources - friends and relatives - to get tobacco, and there is little evidence that these individuals are obtaining tobacco from the illegal commercial market.
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Between ages 15 and 17, mobility increases with driving privileges, and social networks and potential sources of tobacco start to increase as some adolescents take on part-time jobs with co-workers who may be over the MLA.
Therefore, increasing the MLA to 19 may not change social sources substantially for this age group, but raising the MLA to 21 is likely to have a considerable impact on initiation, the study suggests.
The committee emphasised that policy decisions about the MLA should consider other factors in addition to projected health outcomes. One of those factors is the relative maturity of adolescents and young adults.
Of the people who have ever smoked daily, 90 per cent first tried a cigarette before 19 years of age, and nearly all others tried their first cigarette before the age of 26.
If the MLA were raised now, the report says that in 2100 there would be about a 3 per cent decrease in smoking prevalence for an MLA of 19, a 12 per cent decrease for an MLA of 21 and a 16 per cent decrease for an MLA of 25.
Given the likelihood that raising the MLA would decrease the rates of initiation of tobacco use, tobacco-related disease and death consequently also would decrease, researchers said.