Drinking and Driving: Why do we have a limit?
- 1. 16 Here are some Websites that you may find useful: Think! Drink driving http://www.dft.gov.uk/think/focusareas/driving/drinkdriving? page=FAQ Drink-driving and the law: www.drinkdriving.org NHS information on drink-driving: http://www.nhs.uk/chq/ Pages/853.aspxCategoryID=87&SubCategoryID=871 Drinking and driving: over the limit How does alcohol affect driving and why do we have a drink-drive limit?
- 2. 2 What we cover in this booklet: This resource is aimed at 14-18 year olds and for those who are completing GCSE science. Page no. ALCOHOL What happens when alcohol gets in to the body? 4-6 How much alcohol is in a drink? 6 How does alcohol affect the body? 7 How does alcohol affect driving? 8 THE DRINK-DRIVE LIMIT What is the drink-drive limit in the UK? 9 What is Blood Alcohol Concentration? 9 How is Blood Alcohol Concentration measured? 9 What can affect Blood Alcohol Concentration? 10 WHY IS THERE A DRINK-DRIVE LIMIT? Reasons for having a limit of zero 12 Reasons against having a limit of zero 13 QUIZ - TEST YOUR KNOWLEDGE! 14-15 15 Important points to take away: Alcohol is a drug, and can have many effects on your body and behaviour. Many of these effects can make driving dangerous. The drink-drive limit in the UK is 0.08% Blood Alcohol Concentration (BAC). BAC is a measure of the volume of alcohol present in the blood. Drinking the same amount of alcohol can affect people in different ways: factors such as gender and body mass can impact on blood alcohol concentration. It can be argued for these reasons that the drink-drive limit should be zero. Countries that have a drink-drive limit of zero have not been shown to have fewer road accident deaths than the UK. Answers to quiz questions: 1) The small intestine (75% of alcohol is absorbed form here). 2) 95% of alcohol is broken down in the liver. 3) Any three of: erratic behaviour, loss of co-ordination, reduced inhibitions, impaired concentration, delayed reactions or increased self-confidence. 4) 0.08% BAC or 80mg of alcohol per 100ml of blood. 5) Any three of: gender, body fat, rate of absorption, rate of elimination, strength of alcohol, rate of consumption. 6) Either: increased accidents due to dangerous driving or alcohol affects people in varying amounts. 7) Either: foods/other products contain alcohol as well as alcoholic drinks or other countries with a limit of zero do not have fewer road accidents than the UK.
- 3. 14 QUIZ - Test your knowledge! Now you have finished the booklet, you should all be experts on drink-driving, right?! Complete the following questions to see how much you have learnt... 1) Where in the body is the majority of alcohol absorbed from? ______________________________________________ 2) What percentage of alcohol is broken down in the liver? ______________________________________________ 3) Name three effects of alcohol that may affect driving: 1. ____________________________________________ 2. ____________________________________________ 3. ____________________________________________ 4) What is the legal drink-drive limit in the UK? ______________________________________________ 5) Name three things that can affect blood alcohol concentration: 1. ___________________________________________ 2. ___________________________________________ 3. ___________________________________________ 6) Give one argument for making the drink-drive limit zero: _____________________________________________ 7) Give one argument against making the drink-drive limit zero: _____________________________________________ Now check your answers on the next page... 3 In 1998, 19% of fatal car crashes in the UK were related to alcohol, and those aged under 34 years have the highest rates of drink-driving. (http://www.ukmotorists.com/drink%20driving%20explained.asp) But what do we mean when we talk about ‘drink-driving’ or ‘driving under the influence’? DEFINITION OF DRINK-DRIVING: “ Operating a motor vehicle whilst the volume of alcohol in your blood is above the legal limit” MOTOR VEHICLE = doesn't just mean cars, but any type of trans- port that has a motor, e.g. Motorbikes, go-karts, mobility scooters, etc. ALCOHOL = refers to ethanol, which is the type of alcohol found in alcoholic drinks LEGAL LIMIT = this is set by law, but may vary in different coun- tries. In some countries this limit is zero! Turn to the next page to learn more about alcohol and the body...
- 4. 4 What happens when alcohol gets in to the body? Well, firstly the alcohol needs to get in to the body: ORAL INGESTION = eating and drinking Swallowed from mouth into oesophagus and then reaches the stomach. After a normal meal, the stomach takes 4-5 hours to empty into the small intestine Once inside, alcohol needs to get into the blood: Alcohol is absorbed mainly in the small intestine, but also in the mouth, throat and stomach. Rate of absorption depends on: **Quantity (lots of alcohol = faster absorption) **Strength (stronger alcohol = faster absorption) **Food (having lots of food in the stomach = slower absorption) http://health.allrefer.com/pictures-images/ stomach-and-small-intestine.html Mouth and throat Stomach Small Intestine http://www.gutenberg.org/ files/18559/18559-h/18559-h.htm INGESTION ABSORPTION 13 Reasons AGAINST making the drink-drive limit zero The UK, USA and Canada have the highest drink drive limits, allowing someone to drive with less than or equal to 0.08% blood alcohol concentration. Alcoholic drinks are not the only things that contain alcohol! Many foods do, including Christmas pudding, sherry trifle and liqueur chocolates. Some mouthwashes also contain alcohol. So your breath may contain traces of alcohol on a breathalyser after eating or even after brushing your teeth! It may not decrease numbers of road traffic accidents Other countries, such as Hungary, have a 0% BAC drink-drive limit. However, the number of road traffic accident deaths per number of people in the population was actually more than that in the UK!
- 5. 12 Reasons FOR making the drink-drive limit zero If alcohol can affect different people in so many ways, why is drinking and driving not banned altogether? Dangerous driving causing accidents We know that drinking alcohol can cause delayed reactions, loss of co-ordination and reduced inhibitions; all of which can increase your chances of having an accident whilst driving a vehicle. If the drink-drive limit were zero then this risk would be eradicated because driving after any alcohol would be banned. Alcohol affects everyone differently We discussed previously how different factors can affect absorption and elimination of alcohol, therefore affecting blood alcohol concentration. Given that there is huge variation in different people (e.g. Weight, height, gender, tolerance and other disease), how do we know that this one limit is appropriate for everybody? The answer is that we do not, the same amount of alcohol consumed can have different effects on different people 5 DISTRIBUTION Now that alcohol is in the blood it can move around the body: Alcohol dissolves in water (it is hydrophilic), it does not dissolve in fat 1 UNIT OF ALCOHOL REMAINS IN THE BLOOD FOR 1 HOUR How many units of alcohol are in each of these drinks? 1) Large glass of wine 2) A pint of beer 3) An average cocktail (answers at bottom of the page) Now the body needs to get rid of the alcohol: 95% of alcohol is metabolised (broken down) in the Liver into non-toxic substances. 5% is eliminated without being broken down the breath, urine, faeces and saliva. What affects elimination of alcohol from the body? Rate of consumption - drinking more than 1 unit per hour = build up of alcohol in the blood. Gender - women have more body fat = alcohol stays in blood longer. Tolerance - heavy drinkers = body becomes used to clearing alcohol and can do it more efficiently. Answers to questions: 1)3 units, 2)2 units, 3) 4-5 units METABOLISM AND ELIMINATION
- 6. 6 Have you got all of that?! Without looking at the previous pages, can you write down briefly what happens to alcohol at each of the following stages: _____________________________________ _____________________________________ _____________________________________ _____________________________________ ____________________________________ ____________________________________ ____________________________________ ____________________________________ __________________________________ __________________________________ __________________________________ __________________________________ _________________________________ _________________________________ _________________________________ _________________________________ Well done! Now check your answers on pages 4 and 5. INGESTION ABSORPTION DISTRIBUTION METABOLISM AND ELIMINATION 11 Why is the drink drive limit not zero? We have talked about how alcohol can affect you and your driving. We know that a drink-drive limit is in place to stop this, and we have looked at how the drink-drive limit is worked out. In 2009, 17% of fatal road accidents were caused by drink-driving (http://think.direct.gov.uk/drink-driving.html) So why do we have a drink-drive limit? Why is it not just zero? Can you write down reasons FOR making the drink-drive limit zero, and reasons AGAINST doing this? Please turn to the next page where we will look at reasons for and against making the drink drive limit zero. Reasons for Reasons against
- 7. 10 What can affect blood alcohol concentration? We discussed previously some factors that affect elimination of alcohol from the body, including gender and amount of body fat: Alcohol is hydrophilic (binds to water), but not to fat. The body consists of fatty tissues and water (blood is made up of mainly water). Women naturally have more body fat than men. If a male and female of the same size and weight drink the same amount of alcohol, who would have a higher blood alcohol concentration? The answer is the female: as you can see on the diagram, the same amount of alcohol has a smaller amount of water to dissolve in than it does in the male. In overweight/obese people the same thing occurs, and they have a high blood alcohol concentration. What else can affect blood alcohol concentration? Rate of absorption - This can depend on: food intake, amount and strength of alcohol consumed and time between eating and drinking. Rate of elimination - This can depend on: rate of consumption, tolerance to alcohol and any liver disease Can you explain why overweight or obese people may reach higher blood concentrations of alcohol than thinner people? Average man Average woman alcohol fat water 7 How does alcohol affect the body? Can you name four effects that alcohol has on the body? 1) ______________________________ 2) ______________________________ 3) ______________________________ 4) ______________________________ Now carry on reading to find out if you are right.... ALCOHOL IS A CENTRAL NERVOUS SYSTEM DEPRESSANT (this means that it slows down activity in the brain) Effects of alcohol include: Can you think how these effects may influence driving ability, and why might this be dangerous? http://ifightthelaw.files.wordpress.com/2010/11/homer-drunk1.jpg Slurred Speech Reduced Inhibitions Loss of co-ordination Erratic behaviour Impaired concentration Flushed face Increased self- confidence and euphoria Delayed reactions
- 8. 8 How does alcohol affect driving? Now that we know how alcohol affects the body, we can consider how this can influence ability to drive: Delayed reactions and impaired concentration: Your reaction time is how long it takes you to re- act to something on the road (e.g. A person walking in front of your car). If you are travelling at 40 miles per hour and your reaction time is delayed by one second, you will travel an extra 17 metres before you press the brakes. Increased self-confidence, erratic behaviour and reduced inhibitions: Increased confidence in your driving ability, and a reduced inhibitions may cause you to take more risks than you normally would and ultimately lead to dangerous driving that puts you and other road users at risk. Loss of co-ordination Driving requires use of your eyes, hands and feet all at the same time! If you aren’t able to co-ordinate all of these effectively you may struggle to maintain control of the vehicle on the road. Can you think of any other ways that driving could be affected? 9 What is the drink-drive limit in the UK? The drink-drive limit is based on the volume of alcohol that is present in your blood (aka the ‘Blood Alcohol Concentration) Blood Alcohol Concentration (BAC) = the volume of alcohol (in milligrams/mg) per 100 millilitres/ml of blood in the body. The Legal Limit in the UK= 80mg of alcohol per 100ml of blood or 0.08% BAC Translated into drinks this means that: Men can drink no more than 4 units before driving Women can drink no more than 3 units before driving Can you remember how many units are in a pint of beer? (check on page 5 if you need reminding!) How is BAC Measured? BLOOD A sample of blood is taken from a vein and analysed to work out how many milligrams of alcohol are present per 100ml of blood. (Less than 80mg is below the legal drink-drive limit) BREATH The police carry breathalyser machines that can measure the amount of alcohol that is present on someone’s breath (remember that small amounts of alcohol are excreted in the breath without being metabolised) URINE In a similar way to a breathalyser, the amount of un-metabolised alcohol in the urine can help to predict the concentration of alcohol in the blood.