Drinking & Driving

Drinking and Driving

Blood Alcohol Concentration (BAC)

 ·         BAC is the amount of alcohol in the blood stream

 ·         A BAC level of 0.5 means that an individual has 0.5 g of alcohol in his/her body for every 1 litre of blood

 ·         Taking a standard drink of 10g of alcohol, BAC will generally increase by 0.2-0.3 for women and 0.1-0.2 for men for each standard drink

 ·         A BAC will generally decrease by approximately 0.2-0.1 per hour (¾ to 1 standard drink, or 8 g of alcohol per hour)

 ·         The BAC will increase sharply when alcohol is consumed on an empty stomach


Absorption and metabolism of alcohol

After an alcoholic drink is consumed, the alcohol is absorbed rapidly from the stomach and intestine into the bloodstream. The blood alcohol level after drinking a specific number of drinks depends on the rate of drinking and the rate at which it is broken down in the liver by the enzyme alcohol dehydrogenase or ADH. The capacity of the liver to break down alcohol is limited, so if the liver has to handle more alcohol than its capacity for break down, the remaining alcohol will circulate in the blood to other organs and tissues of the body, such as the brain. Alcohol usually starts to affect the brain within about 5 minutes of being swallowed.

Even small amounts of alcohol can influence the ability to drive, so the only safe advice is to avoid any alcohol if driving. The influence of alcohol on individuals varies depending on:

 1.       body weight

 2.       gender (men process alcohol faster than women)

 3.       how fast you drink

 4.       metabolism

 5.       age and/or

 6.       conditions under which alcohol is consumed (i.e. with or without food).

For example, a woman’s BAC generally increases higher than a man’s since women tend to be smaller and have more fat tissue per kg body and less body water compared to men. Consequently, alcohol is more concentrated in the woman’s blood consuming the same amount of alcohol as a man. In addition, women have less of the enzyme that metabolizes alcohol in their stomach and liver.

Because of the multitude of factors that affect BAC, it is very difficult to assess the own BAC or impairment. Alcohol steadily decreases a person’s ability to drive a motor vehicle safely. Listed below are some of the common negative consequences following the consumption of alcoholic beverages.


How alcohol affects driving


Many of the functions that are needed to drive safely are affected when alcoholic beverages are consumed: the brain takes longer to receive messages from the eye; processing information becomes more difficult; and instructions to the body's muscles are delayed resulting in slower reaction times.


Blurred and double vision can also occur, which means the ability to see things correctly while driving is reduced. Individuals are also more likely to take potentially dangerous risks behind the wheel if they've been drinking alcoholic beverages.


Consequences on the psychomotor functions of the driver:

 ·        Coordination and capacity to react decrease

 ·       Capacity to judge speed, distance and the relative position of the vehicle is affected

 ·       Capacity to follow a trajectory or to face an unexpected event is affected


Consequences on the vision of the driver:

 ·         Field of vision is reduced and peripheral vision is altered

 ·         Recovery of sight after a flash is delayed

 ·         Even with low alcohol levels in the blood, the capacity to see, follow, and accommodate objects is deteriorated


Consequences for behaviour and attitude:

 ·         Alcohol may alter driving behaviour and reactions may become aggressive or neglectful

 ·         It may induce feelings of over-confidence, which can give rise to reckless decisions

Driving while either intoxicated or drunk is dangerous and drivers with high blood alcohol concentration (BAC) are at greatly increased risk of car accidents, highway injuries and vehicular deaths. It is recommended not to drive when drinking. In most European countries, the limit is usually 0.5 g per 1 l of blood. For novice drivers, in some countries, limit is 0  g.

An updated and comprehensive international BAC limits table can be found on the International Center for Alcohol Policies (ICAP) website. For more information and data on European Road Safety you can also visit the European Commission DG Mobility and Transport website.


The above summary provide an overview of the topic, for more details and specific questions, please refer to the articles in the database.

AIMS: It is generally accepted, but not yet documented that the risk of future alcoholism increases with the amount of alcohol consumed. The objective of this study was to investigate this association using the Copenhagen City Heart Study. METHODS: Quantity and frequency of alcohol intake was measured in 19 698 men and women randomly drawn from the Copenhagen Population Register in 1976-78. The study population was linked to three different registers in order to detect alcoholism, and average follow-up time was 25 years. RESULTS: After adjustment for all putative confounders, the risk of alcoholism for women increased significantly at 1-7 drinks per week with a hazard ratio (HR) of 2.02 (95% confidence interval (CI): 1.16, 3.53) compared to never/almost never…
The objective of this paper was to determine separately the lifetime risk of drinking alcohol for chronic disease and acute injury outcomes as a basis for setting general population drinking guidelines for Australia. Relative risk data for different levels of average consumption of alcohol were combined with age, sex, and disease-specific risks of dying from an alcohol-attributable chronic disease. For injury, combinations of the number of drinks per occasion and frequency of drinking occasions were combined to model lifetime risk of death for different drinking pattern scenarios. A lifetime risk of injury death of 1 in 100 is reached for consumption levels of about three drinks daily per week for women, and three drinks five times a week for men.…
BACKGROUND: Studies have indicated an increasing proportion of heavy drinking among middle-aged and older Danes. Trends in consumption are often extremely sensitive to influence from various components of the time trends but only few have explored the age, period and cohort-related influences on late life alcohol consumption. By using age, period, and cohort modeling this study explores the time trends in heavy drinking. METHODS: Data derive from five National Health and Morbidity Surveys conducted by the Danish National Institute of Public Health in 1987, 1994, 2000, 2003, and 2005. A total of 15,144 randomly selected Danes between the age of 50 and 74 were interviewed about their alcohol intake on the last weekday and their alcohol intake in the last…
Dietary ethanol (alcohol) is the most widely consumed drug worldwide. High levels of mortality, morbidity, and social malaise are associated with abuse of alcohol, and increasing numbers of women and youth are abusing alcohol. However, strong epidemiological data demonstrate a U- or J-shaped relationship between volume of alcohol consumed and all-cause mortality or disease burden. Moderate alcohol consumption is associated with a lower risk of all-cause mortality and disease burden than are abstinence and immoderate drinking. A brief review of the absorption, distribution, metabolism, and excretion of ethanol is provided with a discussion of the impact of gender differences. Potential mechanisms by which ethanol, ethanol metabolites, and (or) phytochemicals, as associated with different types of ethanol-containing beverages, are discussed in…
A meta-analysis of 6 studies found that regular drinkers of alcoholic beverages have a reduced coronary heart disease (CHD) risk compared to abstainers while irregular drinkers have an increased risk. This investigation suggests that binge and heavy irregular drinking modify the favourable effect of alcohol intake on CHD risk. OBJECTIVE: To evaluate the strength of the evidence provided by epidemiological literature investigating drinking pattern as effect modifier of alcohol intake on the risk of coronary heart disease (CHD). DESIGN: Meta-analysis of observational studies. DATA SOURCES: Medline, citation tracking, from 1966 to 2006. Review methods: Original studies investigating the amount of alcohol intake, combined with the frequency of alcohol consumption and/or pattern of alcohol drinking affecting the risk of CHD were…
Page 3 of 3


The authors have taken reasonable care in ensuring the accuracy of the information herein at the time of publication and are not responsible for any errors or omissions. Read more on our disclaimer.