The effectiveness of reducing illegal blood alcohol concentration (BAC) limits for driving: Evidence for lowering the limit to .05 BAC

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Abstract

Purpose

This scientific review provides a summary of the evidence regarding the benefits of reducing the illegal blood alcohol concentration (BAC) limit for driving and providing a case for enacting a .05 BAC limit.

Results

Fourteen independent studies in the United States indicate that lowering the illegal BAC limit from .10 to .08 has resulted in 5–16% reductions in alcohol-related crashes, fatalities, or injuries. However, the illegal limit is .05 BAC in numerous countries around the world. Several studies indicate that lowering the illegal per se limit from .08 to .05 BAC also reduces alcohol-related fatalities. Laboratory studies indicate that impairment in critical driving functions begins at low BACs and that most subjects are significantly impaired at .05 BAC. The relative risk of being involved in a fatal crash as a driver is 4 to 10 times greater for drivers with BACs between .05 and .07 compared to drivers with .00 BACs.

Summary

There is strong evidence in the literature that lowering the BAC limit from .10 to .08 is effective, that lowering the BAC limit from .08 to .05 is effective, and that lowering the BAC limit for youth to .02 or lower is effective. These law changes serve as a general deterrent to drinking and driving and ultimately save lives.

Impact on Industry

This critical review supports the adoption of lower illegal BAC limits for driving.

Introduction

The international trend toward lowering BAC (blood alcohol concentration) limits has been continuing for some time now, with most industrialized nations reducing their illegal limit to a BAC of .05 or lower. The illegal limit is .05 BAC in Australia, Austria, Belgium, Bulgaria, Croatia, Denmark, Finland, France, Germany, Greece, Israel, Italy, the Netherlands, Portugal, South Africa, Spain, and Turkey. Norway, Russia, and Sweden have a limit of .02 BAC, and Poland recently adopted .03 BAC. This trend has not developed in a vacuum; a myriad of studies have indicated that lowering illegal BAC limits is in the best interest of the public. For example, laboratory studies indicate that impairment in critical driving functions begins at low BACs (Moskowitz & Fiorentino, 2000). Most subjects in laboratory studies are significantly impaired at .05 BAC regarding visual acuity, vigilance, drowsiness, psychomotor skills, and information processing, compared to their performance at .00 BAC (Moskowitz, Burns, Fiorentino, Smiley, & Zador, 2000). The relative risk of being involved in a fatal crash as a driver is 4 to 10 times greater for drivers with BACs between .05 and .07, compared to drivers with .00 BACs (Zador, Krawchuk, & Voas, 2000). A recent study by the National Highway Traffic Safety Administration (NHTSA) in the United States indicates that drivers at .05 BAC have a significantly higher relative risk (ratio of 1.38 to 1.00) of being involved in a traffic crash than drivers at .00 BAC (Compton et al., 2002). Leading medical, crash prevention, public health, and traffic safety organizations in the world support BAC limits at .05 or lower, including the World Medical Association, the American and British Medical Associations, the European Commission, the European Transport Safety Council, the World Health Organization, and the American College of Emergency Physicians (Chamberlain & Solomon, 2002).

This article provides a critical review of the evidence regarding the potential benefits of enacting a .05 BAC per se limit. The first section discusses methodological issues concerning studies of this nature. The second section summarizes the evidence, including the most recent studies, for lowering the BAC limit from .10 to .08. The third section covers the available evidence for lowering the BAC limit to .05. The fourth section reviews the evidence for lowering the BAC limits for drivers younger than age 21. The last section concludes that lowering BAC limits is an effective strategy in reducing impaired-driving casualties.

Section snippets

Discussion of methodologically rigorous studies

The effectiveness of any law is highly dependent on the extent to which it is enforced and the intensity and publicity surrounding that enforcement. When an evaluation of a new impaired-driving law is conducted, it is difficult to control for changes in enforcement activities, changes in public information, changes in other laws, and changes in alcohol consumption, all of which could affect the outcome. When researchers study multiple applications of the same law, there almost always are cases

A summary of the evidence for lowering the BAC limit from .10 to .08

At the start of the 1970s, when the first U.S. national effort at controlling alcohol-impaired driving began, even those states that based their laws on the BACs of drivers merely specified BACs at which it was “presumed” that a person was intoxicated. The presumption could be rebutted by other evidence. The presumptive levels generally were set at .15 BAC, although a few states had BAC levels of .12 or .10. Beginning in the 1970s, the U.S. Department of Transportation (DOT) used its authority

Effectiveness of .05 BAC laws

Several countries have conducted evaluations of lowering their illegal BAC limits to .05 or less. A long-term study of the .05 BAC law in the Netherlands (adopted in 1974) concluded that it contributed to a sustained decline in the total number of drinking drivers involved in crashes (Noordzij, 1994). Another study from France evaluated the impact of lowering its BAC limit from .08 to .05 in 1996. Annual alcohol-related crash fatalities fell from approximately 100 before the legal change to 64

A summary of the evidence for lowering BAC limits for youth

The United States has taken the lead in adopting lower BAC limits for underage youth. In 1984, the U.S. Congress adopted measures to sanction states that did not adopt 21 as their minimum legal drinking age. By 1988, all states had enacted such laws. Because it was illegal for those younger than 21 to drink any alcohol, it seemed logical that underage drivers should have no alcohol in their systems when they drove. In 1995, the U.S. Congress passed a law requiring states to adopt so-called zero

Public support for lower BAC limits

Surveys in the United States indicate that most people believe they should not drive after two or three drinks (Royal, 2000). This is equivalent to a BAC of .05 for many people (NHTSA, 1994). Considering this reported attitude, the public favors a BAC limit of .05. The countries that have already adopted .05 BAC as their limit do not report any public outcry that the limit is too strict.

Conclusion

Mann, Macdonald, Stoduto, Bondy, and Shaikh (1998) reviewed all of the available scientific evidence in assessing the potential impact of lowering the BAC limit to .05. They assessed research on the effects of alcohol on driving performance; epidemiological research on the risk of collision involvement at various BACs; research on the impact of lowering the BAC limit in other countries and jurisdictions; and other possible issues such as public acceptance, police discretion, and judicial

Acknowledgement

The authors would like to thank MADD Canada and, in particular, Andrew Murie, Executive Director, for supporting this critical review of the evidence for lower BAC limits.

James C. Fell presently is a Senior Program Director at the Pacific Institute for Research and Evaluation (PIRE). He has been at PIRE since May, 2001. He is presently involved in managing projects evaluating the effectiveness of traffic safety enforcement programs, particularly highly visible, highly publicized and frequent sobriety checkpoints, in reducing impaired driving. Mr. Fell formerly worked at the National Highway Traffic Safety Administration (NHTSA) from 1969 to 1999 and has 36 years

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  • Cited by (0)

    James C. Fell presently is a Senior Program Director at the Pacific Institute for Research and Evaluation (PIRE). He has been at PIRE since May, 2001. He is presently involved in managing projects evaluating the effectiveness of traffic safety enforcement programs, particularly highly visible, highly publicized and frequent sobriety checkpoints, in reducing impaired driving. Mr. Fell formerly worked at the National Highway Traffic Safety Administration (NHTSA) from 1969 to 1999 and has 36 years of traffic safety and research experience. At NHTSA, he was Chief of Research and Evaluation for Traffic Safety Programs and Manager of the Fatality Analysis Reporting System (FARS). He has authored over 80 scientific publications in the areas of highway safety, alcohol impairment and human factors research. Mr. Fell served on the National Board of Directors for Mothers Against Drunk Driving (MADD) from 1999–2006 and is a member of the International Council on Alcohol, Drugs and Traffic Safety (ICADTS), the Association for the Advancement of Automotive Medicine (AAAM), and the Human Factors and Ergonomics Society (HFES). He has both a Bachelor's and Master's degree in Human Factors Engineering from the State University of New York at Buffalo.

    Robert Voas, a senior scientist with the Pacific Institute for Research and Evaluation (PIRE), has been involved in research on alcohol and highway safety for 30 years, initially as director of the National Highway Traffic Safety Administration's Office of Program Evaluation and more recently as Principal Investigator for government research programs in drinking-driving and community alcohol problem prevention. Dr. Voas has served two terms on the MADD National Board and is currently on the MADD National Advisory Board. Dr. Voas is a Fellow of the American Psychological Association and a Past President of the International Council on Alcohol, Drugs, and Traffic Safety. He is also a member of the Committee on Alcohol and Drugs, the National Safety Council, and the Committee on Alcohol and Other Drugs of the National Transportation Research Board and has served on the National Board of Mothers Against Drunk Driving (MADD). His recent research projects have included an evaluation of programs to reduce college student binge drinking and studies of underage binge drinkers crossing the border at San Diego and El Paso to drink in Mexico, where the drinking age is 18. He has recently conducted national studies of the impact of .08 laws, the zero tolerance laws, vehicle impoundment laws, and interlock laws.

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