Drink-driving and perceptions of legally permissible alcohol use

The leading cause of death for young people in developed countries is road traffic crashes, a large proportion of which are attributable to drink-driving. The aims of the study were to estimate the prevalence of drink-driving and drink-riding in a sample of New Zealand university students, and to identify potential risk factors, in particular, students' perceptions of legally permissible consumption before driving.

Participants were 1,564 survey respondents (82% response, mean age = 20.5 years) who were asked to indicate whether they had driven after having "perhaps too much to drink to be able to drive safely," if they had been a passenger in a vehicle "where the driver had perhaps too much to drink to be able to drive safely," and how many standard drinks they could consume in one hour and legally drive a car. An estimated blood alcohol concentration was computed and compared with legal limits.

Drink-driving (past four weeks) was reported by 3.4% of women and 8.4% of men. Drink-riding (past four weeks) was reported by 7.0% of women and 11.5% of men. Estimated blood alcohol concentrations from students' reports of how much they could drink in one hour and be below the legal limit of 0.08 g/ml, showed that most respondents dramatically underestimated permissible consumption; only 5.8% overestimated it.

This may be a case where misperception of a public health message serves the public good. Further reductions in drink-driving/riding will require attention to transport needs, more visible enforcement of existing legislation, and modification of youth drinking behavior.