College Students' Underestimation of Blood Alcohol Concentration from Hypothetical Consumption of Supersized Alcopops: Results from a Cluster-Randomized Classroom Study.

Background: Supersized alcopops are a class of single-serving beverages popular among underage drinkers. These products contain large quantities of alcohol. This study examines the extent to which young adults recognize how intoxicated they would become from consuming these products.

Methods: The study sample included 309 undergraduates who had consumed alcohol within the past year. Thirty-two sections of a college English course were randomized to 1 of 2 survey conditions, based on hypothetical consumption of supersized alcopops or beer of comparable liquid volume. Students were provided an empty can of 1 of the 2 beverages to help them answer the survey questions. Equation-calculated blood alcohol concentrations (BACs)-based on body weight and sex-were compared to the students' self-estimated BACs for consuming 1, 2, and 3 cans of the beverage provided to them.

Results: In adjusted regression models, students randomized to the supersized alcopop group greatly underestimated their BAC, whereas students randomized to the beer group overestimated it. The supersized alcopop group underestimated their BAC by 0.04 (95% confidence interval [CI]: 0.034, 0.053), 0.09 (95% CI: 0.067, 0.107), and 0.13 g/dl (95% CI: 0.097, 0.163) compared to the beer group. When asked how much alcohol they could consume before it would be unsafe to drive, students in the supersized alcopop group had 7 times the odds of estimating consumption that would generate a calculated BAC of at least 0.08 g/dl, compared to those making estimates based on beer consumption (95% CI: 3.734, 13.025).

Conclusions: Students underestimated the intoxication they would experience from consuming supersized alcopops. Revised product warning labels are urgently needed to clearly identify the number of standard drinks contained in a supersized alcopop can. Moreover, regulations are needed to limit alcohol content of single-serving products.