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; edward_adlaf@camh.net

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.

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.

References

1. Statistical report on the health of Canadians. Ottawa: Statistics
Canada; 1999. Cat no 82-570-X1E.

2. US Department of Public Health and Human Services. Healthy people 2010.
Washington: The Department; 2000.

3. Simpson HM. Polydrug effects and traffic safety. Alcohol Drugs Driving
1985; 1: 17-44.

4. Borkenstein RF, Crowther RF, Shumate RP, Zeil WB, Zylman R. The role of
the drinking driver in traffic accidents. Bloomington (IN): Department of
Police Administration, Indiana University; 1964.

5. Mann RE, Macdonald S, Stoduto G, Shaikh A, Bondy S. Assessing the
potential impact of lowering the legal blood alcohol limit to 50 mg% in
Canada. Ottawa: Transport Canada; 1998. Publ no TR 13321 E.

6. Adlaf EM, Paglia A. Drug use among Ontario students, 1977-2001: findings
from the OSDUS. Toronto: Centre for Addiction and Mental Health; 2001.

7. Mann RE, Macdonald S, Stoduto LG, Bondy S, Jonah B, Shaikh A. The
effects of introducing or lowering per se blood alcohol limits for driving:
an international review. Accid Anal Prev 2001;33(5):569-83.[Medline]

8. Paglia A, Room R. Preventing substance use problems among youth: a
literature review and recommendations. J Prim Prev 1999;20(1):3-50.

9. Stoduto G, Adlaf EM. Drinking and driving among Ontario high school
students, 1977-1995. Can J Public Health 1996;87(3):187-8.[Medline]

10. O'Malley PM, Johnston LD. Drinking and driving among US high school
seniors, 1984-1997. Am J Public Health 1999;89(5):678-84.[Abstract]

11. Stewart K, Klitzner M. Youth anti-drinking-driving program. In: Wilson
RJ, Mann RE, editors. Drinking and driving: advances in reseach and
prevention. New York: Guilford Press; 1990. p. 226-49.

12. Everett S, Shults R, Barrios L, Sacks J, Lowry R, Oeltmann J. Trends
and subgroup differences in transportation-related injury risk and safety
behaviors among high school students, 1991-1997. J Adolesc Health
2001;28(3):228-34.

13. Kann L, Kinchen SA, Williams BI, Ross RL, Grunbaum J, Kolbe LJ. Youth
risk behavior surveillance -- United States, 1999. J Sch Health
2000;70(7):271-85.[Medline]

14. Walsh G, Mann RE. On the high-road: driving under the influence of
cannabis in Ontario. Can J Public Health 1999;90:260-3.[Medline]

15. Macdonald S, Mann RE, Chipman ML, Anglin-Bodrug K. Collisions of
alcohol, cannabis and cocaine abuse clients before and after treatment.
16th International Conference on Alcohol, Drugs and Traffic Safety -- T
2002; 2002 Aug 4-9; Montreal.