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.

Alcohol consumption is a risk factor for motor vehicle accidents in young drivers. Crashes associated with alcohol consumption typically have greater severity. This study examines the prevalence of driving under the influence among Spanish youth and tests the theory of reasoned action as a model for predicting driving under the influence. Participants included 478 Spanish university students aged 17-26 years. Findings indicated that alcohol was the substance most associated with impaired driving, and was involved in more traffic crashes. Men engage in higher levels of alcohol and other drug use, and perceived less risk in drunk driving (p < .01). The study confirms that alcohol use and driving under the influence of alcohol are highly prevalent in Spanish young people,…
AIMS: The main objective of this article was to compare alcohol and tobacco consumption in the US and the Basque Country (the North of Spain) with particular attention to the association between alcohol and tobacco use. The consistency of findings was considered by analyzing data from two different years. These comparisons may provide a rational basis for exploring the associations between alcohol and cigarette use that are influenced by changes in use prevalences. METHODS: Two epidemiological samples from the US, obtained in 1992 and 1996, and two from the Basque Country, obtained in the same years, were used. Sampling methodologies were similar. Questionnaires were self-administrated with the help of interviewers, and were used to define ever smokers, ex-smokers, current smokers,…
OBJECTIVES: Maternal alcohol use is a leading preventable cause of neurobehavioral and developmental abnormalities in children. This study examines the patterns and average volume of alcohol use among U.S. women of childbearing age in order to identify subgroups of high-risk women for selective intervention. METHODS: A sample of 188,290 women aged 18-44 years participated in the Centers for Disease Controls and Prevention (CDC)'s Behavioral Risk Factor Surveillance System (BRFSS) survey during the period of 2001-2003. Reported alcohol use patterns and average volume were examined for pregnant and nonpregnant women. Efforts were made to evaluate and characterize women who practiced various levels of binge drinking. RESULTS: The results showed that approximately 2% of pregnant women and 13% of nonpregnant women in…
AIMS: To give an overview of the volume of alcohol consumption, beverage preference, and patterns of drinking among adults (people 15 years and older) in central and eastern Europe (Bulgaria, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Romania, Slovakia, and Slovenia) and to compare it to southern and western Europe, Russia and Ukraine. METHODS: Secondary data analysis. Consumption and preferred beverage type data for the year 2002 were taken from the WHO Global Status Report on Alcohol and the WHO Global Alcohol Database. RESULTS: Average consumption in central and eastern Europe is high with a relatively large proportion of unrecorded consumption ranging from one litre in Czech Republic and Estonia to 10.5 l in Ukraine. The proportion of heavy alcohol…
AIM: The aim of this study was to investigate the utility of a short, practical pouring exercise as a means of illustrating the details of the UK 'Sensible Drinking' guidelines. METHODS: Participants (N = 297, 53% male) recruited at four Edinburgh employment sites, each completed a short non-standardized questionnaire and poured their 'usual measure of wine or spirit' into a glass (purchased from four 'high street' outlets). The actual and estimated unit content of their poured drinks and reactions to feedback were noted. Participants were informed of their daily limit of consumption in terms of this drink. RESULTS: On average, drinks contained 2.05 UK units. Only 27% (N = 79) of respondents estimated the unit content of their drink within…
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