Pubdate: Tue, 04 Mar 2003
Source: Canadian Medical Association Journal (Canada)
Copyright: 2003 Canadian Medical Association
Contact:  http://www.cmaj.ca/
Details: http://www.mapinc.org/media/754
Authors: Edward M. Adlaf, Robert E. Mann and Angela Paglia

DRINKING, CANNABIS USE AND DRIVING AMONG ONTARIO STUDENTS

 From the Centre for Addiction and Mental Health (all authors), and the 
Department of Public Health Sciences, Faculty of Medicine, University of 
Toronto (Adlaf and Mann), Toronto, Ont.

Correspondence to: Dr. Edward M. Adlaf, Head, Population and Life Course 
Studies, Centre for Addiction and Mental Health, 33 Russell St., Toronto ON 
M5S 2S1; fax 416 595-6899; Abstract

LITTLE IS KNOWN ABOUT THE RISK OF INJURY among adolescents who drive after 
the use of alcohol or cannabis or ride in cars driven by drunk drivers. We 
examined data from self-administered interviews with 1846 students in 
grades 7 to 13 who participated in the 2001 Ontario Student Drug Use Survey 
about their experiences related to alcohol, cannabis and driving during the 
12 months preceding the survey. In all, 31.9% of the students reported 
being a passenger in a car driven by a drunk driver; of the students in 
grades 10 to 13 who had a driver's licence, 15.1% reported driving within 
an hour after consuming 2 or more drinks, and 19.7% reported driving within 
an hour after using cannabis. Our study shows that a sizeable proportion of 
adolescents are exposed to alcohol- and drug-related driving risks.

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Alcohol-related motor vehicle collisions are a major source of injury among 
adolescents.1,2,3,4,5 Efforts to reduce the prevalence of drunk driving 
have been undertaken, with some success.5,6,7,8,9 Specific initiatives in 
Ontario have included the introduction of a zero blood alcohol content 
(BAC) requirement as part of the province's Graduated Licensing System. 
Introduced in 1994, this system applies restrictions to all new drivers in 
the first 2 years of licensing. In addition to the BAC restriction, new 
drivers are also limited in the conditions under which they can drive. 
Other recent initiatives have included the introduction in 1996 of the 
Administrative Driver's Licence Suspension Program, which allows police to 
immediately suspend a driver's licence for 90 days if he or she has a BAC 
over the legal limit or refuses a breath test, and the requirement that all 
people convicted of drunk driving complete a remedial program before they 
are eligible for relicensing following the period of mandatory licence 
suspension.

Although some research has monitored the prevalence of drinking and driving 
among adolescents, which is now about 15%,6,9 little is known about the 
risk of injury associated with driving after the use of drugs such as 
cannabis or with secondary exposure such as being a passenger in a car 
driven by a drunk driver. These 2 issues are of concern given that US data 
suggest about one-third of adolescents have ridden with a driver who had 
been drinking10,11,12,13 and that about 9% of Ontario drivers aged 18-19 
years reported driving after cannabis use.14 We present here data on these 
indicators from a representative sample of Ontario students who 
participated in the Ontario Student Drug Use Survey (OSDUS).

The OSDUS is funded by the Centre for Addiction and Mental Health, Toronto, 
and has been conducted every 2 years since 1977. We analyzed data from the 
2001 survey. The survey used a 2-stage cluster design (school, class) and 
included 4211 students in grades 7 to 13 from 41 school boards and 106 
schools (43 elementary, 63 secondary). The student cooperation rate was 
71%. This study was approved by the joint Research Ethics Board of the 
Centre for Addiction and Mental Health and the University of Toronto.

To maximize questionnaire coverage, the OSDUS uses random half samples for 
selected questionnaire items. Our estimates are based on 3 samples: 
passenger involvement was determined from the responses of 1846 students in 
a random half sample of all students; drunk-driving involvement was 
determined from the responses of 1119 students in grades 10 to 13 from the 
full sample who had a driver's licence; and cannabis involvement was 
derived from the responses of 508 students in a half sample of drivers in 
grades 10 to 13.

Self-administered questionnaires were administered by staff of the 
Institute for Social Research, York University, in a classroom setting. The 
students were asked 3 questions: "How often in the last 12 months did you 
ride in a car or other vehicle driven by someone who had been drinking 
alcohol?"; "How often in the last 12 months have you driven within an hour 
of drinking 2 or more drinks of alcohol?"; and "How often in the last 12 
months have you driven within an hour of using marijuana or hashish?" For 
analysis purposes, responses were binary coded indicating involvement at 
least once during the 12 months before the survey. Further details 
regarding the study are available from the authors.6 All estimates were 
weighted, and variance and statistical tests were corrected for the complex 
sample design.

Our findings are summarized in Table 1. In all, 31.9% of the students 
reported being a passenger in a car driven by someone who had been 
drinking. Passenger involvement was unrelated to sex but did differ 
significantly by grade. Of the students in grades 10 to 13 who had a 
driver's licence, 15.1% reported driving within an hour after consuming 2 
or more drinks; the proportion varied significantly by sex and grade. Of 
the half sample of drivers, 19.7% reported driving within an hour after 
using cannabis; the rates varied significantly by sex only.

View this table: Table 1.

Our study has limitations, the main one being that the data were 
self-reported and may have been subject to nonresponse bias. However, this 
source of bias would most likely serve to underestimate true behaviour.

Three of our findings have important public health implications that 
require further research and monitoring. First, the 15% of students with a 
driver's licence who reported driving after drinking is excessive, 
particularly since almost all were under the legal drinking age, and most 
had a graduated licence, for which the legal BAC limit is zero. Second, 
that nearly one-third of the students reported having ridden in a car 
driven by someone who had been drinking -- an exposure associated with the 
largest risk factor for the leading cause of death among adolescents1 -- is 
of great concern. Third, driving after cannabis use is a risk behaviour 
that may be of similar magnitude to driving after drinking.15 Although 
there are no earlier data to evaluate trends, the potential exposure may be 
substantial since a sizeable proportion of adolescent students are drivers 
(30%) and have used cannabis (30%).6

Footnotes

This article has been peer reviewed.

Contributors: Dr. Adlaf and Ms. Paglia were involved in the study design, 
data acquisition, analysis and interpretation, and manuscript preparation. 
Dr. Mann was involved in the data analysis and interpretation and the 
manuscript preparation. All authors approved the final version of the article.

Competing interests: None declared.

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