Alcohol

Question 1

LO

Answer 1

* What is alcohol?
* Alcohol in the body
* Effects of alcohol
* Legislation
* Samples
* Breath testing equipment
* Calculations

Question 2

What is alcohol?

Answer 2

• Specifically, “alcohol” is the name of a family of simple chemical compounds characterised by an –OH functional group
• However, what everyone means by ‘alcohol’ is of course the stuff we drink: ethanol

Question 3

Origins of alcohol and how is alcohol produced?

Answer 3

• Alcohol is produced by the fermentation of natural simple sugars
• During anaerobic fermentation, the yeast feeds on the simple sugars in the fruit and produces ethanol and carbon dioxide
• The principal yeast involved is Saccharomycetes cerevisiae, which occurs naturally on the skin of grapes and other fruit. Any grapes with broken skin are therefore likely to ferment naturally … in fact it is difficult to stop it
• The wild grape vine, Vitis vinifera ssp sylvestris is widely distributed in the Mediterranean and Anatolia

Question 4

The evolution of wine

Answer 4

• This process is called ‘the Palaeolithic hypothesis’
  1. Yuk, this fruit’s gone off!
  2. Actually, this gone-off fruit is not so bad….
  3. Any more of that gone-off fruit?
  4. How can we make more fruit go off?
• The deliberate, systematic production of alcoholic drinks requires pottery, a Neolithic innovation
• Alcohol has been produced pretty much universally from then onwards
• We tend to think of wine as a more sophisticated drink than beer, but from a biochemical point of view this is not the case

Question 5

What is the main grain used to make beer and how is beer made from this?

Answer 5

• Cereal grains such as barley (the main grain used to make beer) contain starch, not simple sugars
• To make beer, complex sugars such as starch must be converted to simple sugars, such as glucose, before fermentation takes place.
• This process is known as malting and requires the grain to “sprout” which converts the starch to simple sugars to be used as energy for growth

Question 6

The evolution of beer

Answer 6

• Beers produce a rather messy crust of yeast and bits of grain, and in ancient times were often drunk through straws or drinking tubes to avoid the worst of it, as this Egyptian gentleman is doing (about 1350 BC)
• Nowadays, when fermentation has gone as far as the brewer requires, the fermentation is stopped, the mixture (known as a “wort”) is filtered, and packaged ready for sale
• … and in case you thought this a peculiar habit of the Ancients, here are some modern Chinese from the Qiang people of Yunnan, China, doing much the same, but communally

Question 7

Tell me how spirits are made

Answer 7

• Spirits are prepared in a similar way up until fermentation is stopped
• The mixture (known as a “wash”) is then heated, and the volatile components are distilled off
• This results in a clear, colourless liquid of about 65% alcohol by volume
• Most of the volatile component is ethanol, although other compounds (collectively known as congeners) are usually present, with a characteristic profile depending on the ingredients used in the fermentation process to make whisky, the alcohol/water distillate is then put into wooden casks for several years
• The length of time in the cask gives the age of the whisky – it does not get any “older” in the bottle…
• The distillate absorbs colour and flavour from the wood which, combined with the mixture of grain used, gives each whisky its unique taste

Question 8

• Drinks can be made from a variety of starting materials such as?

Answer 8

o Rice – sake
o Potatoes – vodka, poitín
o Apples – cider, cider brandy
o Pears – perry
o Sugarcane – rum
o Honey – mead
o In fact, anything carbohydrate-based can be used…

Question 9

How is ethanol taken into the body?

Answer 9

• Ethanol is usually ingested via the mouth
• Very occasionally injected, even rarer absorption through the eye: as eye is a mucous membrane
• Inhalation is sometimes claimed, but has no effect on alcohol level
• Likewise, absorption through the skin has no effect - even where open wounds are present

Question 10

How quickly the ethanol is absorbed depends partly on what?

Answer 10

How quickly the ethanol is absorbed depends partly on the strength of the ethanol mixture:

o Weak drinks (<5% ABV) are absorbed slowly due to the large excess of water.

o Beers in particular have a high carbohydrate level which will further slow the absorption

o Strong drinks (>40% ABV) will cause the stomach sphincter to spasm, releasing small amounts at a time.

o** High ethanol concentrations **will cause over-production of stomach mucus which also slows absorption

• Mid-strength drinks (approximately 20% ABV) are absorbed quickest as they have the optimal ethanol concentration. Not too strong that it irritates the stomach, and not too weak that the ethanol is overwhelmed by the water content

Question 11

Whats absorbed quicker, carbonated or non-carbonated drinks?

Answer 11

Additionally, carbonated drinks are absorbed quicker than the equivalent strength non-carbonated drink.

This is because the carbonated drinks increase the pressure in the stomach and forces more of the alcohol into the blood stream

Question 12

Factors which may slow down ethanol absorption

Answer 12

o Whether food has been eaten
o Smoking
o Weak drinks (<5% ABV)
o Fatty or carbohydrate-rich foods (or drinks)
o Drinking in the afternoon/evening (when blood sugar is at a “normal” level)
o Note: There is an apparent lowering of total ethanol amount when absorption is slowed. This may be due to the longer time allowing for significant 1st-pass metabolism, or may be due to the ethanol binding to food – hence there is less available for absorption

Question 13

Factors which may speed up ethanol absorption

Answer 13

o Drinking in the morning (or after a significant fasting period)
o Low blood sugar levels (see also the point above)
o Strong alcoholic drinks (less water volume)
o Carbonated drinks (because they increase gastric emptying)
o Gastric band surgery (reduces stomach volume, and hence the stomach needs to empty more often)
o Gastric bypass surgery (some ingested food and drink will bypass the stomach and go directly to the small intestine)

Question 14

Where does absorption, metabolism and excretion occur and roughly how much?

Answer 14

* Absorption:
o Stomach 20%
o Large and small intestine 80%

* Metabolism (around 95%)
o Liver enzymes

* Elimination (around 5%)
o Breath, sweat, urine

Question 15

Ethanol absorption/ elimination curves

Answer 15

Question 16

Ethanol absorption/ elimination curves

Answer 16

Question 17

What happens to ethanol once it is in the body?

Answer 17

• Once absorbed, ethanol is eventually distributed equally throughout all of the water in the body
• This is not restricted to water itself, but also blood (about 80% water), and muscle tissue
• It is not distributed in any lipid (fat) cells

Question 18

Because of the route of absorption and distribution of ethanol, there is a small, but measurable, difference between what?

Answer 18

arterial blood and venous blood

Initially the arterial blood concentration is higher. For a very brief moment the arterial and venous blood concentrations are the same. During the elimination phase, the venous blood concentration is higher.

Question 19

Ethanol is volatile, what does this mean?

Answer 19

• Because ethanol is volatile, if there is ethanol in the blood, there must be ethanol in the breath
• There is an equilibrium when the exhalation reaches “deep lung air” or “alveolar air”
• However, when you start to exhale, there is very little ethanol in the first few mls of breath

Question 20

What is a typical breath alcohol profile?

Answer 20

Question 21

How is most ethanol eliminated?

Answer 21

• Most ethanol is eliminated via oxidative metabolism (95 -98%) in the liver by ADH
• The rest (<5%) is eliminated via breath, sweat, and urine
• A very small amount (<0.1%) is eliminated via non-oxidative metabolism to ethyl glucoronide and ethyl sulfate – markers in urine for recent drinking

Question 22

What is the ADH metabolic pathway?

Answer 22

ethanol → acetaldeyhyde (by alcohol dehydrogenase) → acetic acid or acetate (by aldehyde dehydrogenase)

Question 23

What is the drug Antabuse/ Disulfiram for?

Answer 23

The drug Antabuse which is prescribed to alcoholics blocks the second metabolic pathway above, leading to high levels of acetaldehyde (very unpleasant effects!!!)

Question 24

What is the effect of alcohol?
What can it cause in low and higher doses?

Answer 24

• Alcohol is a central nervous system depressant
• At low doses it induces a feeling of well-being (euphoria), often with increased self-confidence leading to sociability and talkativeness
• In greater amounts it cause emotional mood swings, impaired judgement and sensory perception, and increased reaction times
• At higher doses alcohol may cause confusion, disorientation, nausea, slurred speech and drowsiness

Question 25

What are some effects of alcohol?

Answer 25

It impairs memory, understanding, balance and co-ordination (which can be assessed during a Preliminary Impairment Test)

Question 26

What can levels of alcohol above about 250 to 300 mg% cause?

Answer 26

Above about 250 to 300 mg%, apathy, inertia, decreased sensitivity to pain, stupor, vomiting and incontinence may occur

Question 27

What is the fatal alcohol level?

Answer 27

The fatal level is typically >400 mg%, but is possible at any level above 350 mg% or so (but note some drivers >400 mg%)

• The highest ever BAC recorded in a “drink driver” was 720mg/100ml (although they were unconscious when found in their car…).

Question 28

What is the link between alcohol and violence?

Answer 28

• Alcohol is involved in a large proportion of acts of violence: between 50 and 80% in different studies. Of offences in which the arrestee had drunk alcohol, 67% were violent or public-order offences
• Alcohol causes ‘disinhibition’, which may help in social situations, but also causes an increase in what sociologists call ‘impulsivity’
• This is the urge to act immediately (on impulse) to a stimulus such as rejection or a perceived threat, without regard to the negative effects on the object of the aggression, or the subject themselves
• Foresight as to the consequences of one’s actions is an important component in inhibiting violence (and antisocial behaviour generally) in most people, and the lack of such foresight makes aggression and violence (including sexual violence) more likely.

Question 29

Why does alcohol lead to hangovers?

Answer 29

• Alcoholic drinks contain a varying range of other substances, called congeners: other alcohols, acids, aldehydes, ketones and esters
• Drinks like brandy, red wine and malt whisky contain more of these, and vodka and gin fewer

* Congeners are responsible for some of the persistent symptoms of hangover

• Methanol for example (found in red wine, port, brandy, etc), is metabolised by ADH as follows:
  methanol → formaldehyde → formic acid
• Alcohol can cause vomiting, not only by irritating the stomach but by acting directly on the vomit centre in the brain (can be induced by IV alcohol administration)
• Alcohol is a powerful diuretic, and even when taken with lots of water (in beer, for example), the overall effect is of dehydration
• The “hangover headache” is mainly due to dehydration, and can be alleviated by drinking water (before sleep is better than once you’ve woken up in the morning)

Question 30

Why can alcohol effect memory and lead to blackouts?

Answer 30

• Blackouts, real or alleged, are a common feature of rape, sexual assault, DFSA and other violent acts
• Unfortunately it is often convenient for defendants, and sometimes complainants, to claim to remember nothing, so it difficult to say how many of these claims might be true
• However, there is no doubt that alcohol can cause blackouts
• Blackouts generally occur at BACs above about 200 mg%, but can happen at lower concentrations … but are not, of course, inevitable
• Blackouts are associated with a rapidly rising BAC (Mellanby effect), and hence with drinking quickly and on an empty stomach
• Blackouts may be en bloc, during which the subject remembers nothing, or fragmentary, of which their memory is, er, fragmentary
• During blackouts the subject may have no memory at all, even of very significant acts
• People have reported driving, spending money, indulging in vandalism, and having unprotected intercourse, all with no memory afterwards
• Blackouts are more common than was once thought
• In one study of American college students, 51% of men who had ever consumed alcohol had experienced a blackout at least once, and 40% in the last year
• Women seem to have about the same frequency of blackouts as men, despite drinking less often and drinking less during each session
• Other things being equal, women would therefore appear to be more susceptible to blackouts than men

Question 31

What can be the long term effects of alcohol and memory?

Answer 31

• Alcohol interferes with the transfer of information from short-term to long-term memory
• Memories acquired whilst drunk may therefore fail to be ‘laid down’ in long-term memory, and be quickly lost
• Memories laid down before an alcoholic started drinking (of childhood, for example) may remain intact
• The extreme form of this is Korsakoff’s syndrome, which generally manifests itself after many years of heavy drinking
• Someone suffering from Korsakoff’s syndrome lives almost entirely in the past. Other than a few seconds of short-term memory, they have only memories laid down before they started drinking to rely on.

Question 32

How does alcohol lead to driving impairments?

Answer 32

• Alcohol is a central nervous system depressant
• At low doses it induces a feeling of well-being (euphoria), often with increased self-confidence leading to sociability and talkativeness
• In greater amounts it cause emotional mood swings, impaired judgement and sensory perception, and increased reaction times
• It impairs understanding, memory, balance and co-ordination (which can be assessed during a Preliminary Impairment Test)
• At higher doses alcohol may cause confusion, disorientation, nausea, slurred speech and drowsiness
• Above about 250 to 300 mg%, apathy, inertia, decreased sensitivity to pain, stupor, vomiting and incontinence may occur
• The fatal level is typically >400 mg%, but is possible at any level above 350 mg% or so (but note some drivers >400 mg%)

Question 33

What all of this tells us…

Answer 33

• That at a BAC above about 40 to 50 mg% you are at an increased risk of being involved in an accident
• The increased risk becomes significant at about 50 mg% - (one of) the legal limit(s) in many countries
• At our legal limit of 80 mg% the increased risk is about 400%
• At 100 mg% the increased risk is roughly 600%; at 150 mg%, about 2,500%
• The increase is approximately exponential

BAC= blood alcohol concentration

Question 34

What are the 3 main Acts which cover “drink driving”?

Answer 34

Road Traffic Act 1988
Transport and Works Act 1992
Railways and Transport Safety Act 2003

Question 35

All of the legislations surrounding alcohol has its origins in the Road Safety Act 1967 and is famous for what three things?

Answer 35

1) The introduction of a specific alcohol limit
2) The introduction of the “breath test”
3) The introduction of a 70mph speed limit on motorways for a trial period of 6-months…

Question 36

The Road traffic act 1988

Answer 36

o Covers “motor vehicles” and “mechanically-propelled” vehicles
o Sets per se limits for alcohol of:
35ug/100ml in breath
80mg/100ml in blood
107mg/100ml in urine

Question 37

The **Transport and works act 1992 **

Answer 37

o Covers “tracked vehicles” and more than just “drivers”
o Uses the same per se limits as the RTA
35ug/100ml in breath
80mg/100ml in blood
107mg/100ml in urine

Question 38

The Railways and Transport safety act 2003

Answer 38

o Has provisions for “professional mariners” and “aircrew”
o Professional mariners have the same limits as the RTA
o The aircrew provisions are a bit more complex…
o “Safety-critical aircrew” have the following limits:
9ug/100ml in breath
20mg/100ml in blood
27mg/100ml in urine
o “Licenced aircraft engineers” have the same limits as the RTA
35ug/100ml in breath
80mg/100ml in blood
107mg/100ml in urine
o “Non-licenced aircraft engineers” have no limit…

Question 39

• All of this legislation is possibly the most litigious area of law in the UK – and all because of the offence of “failing to provide without reasonable excuse”
• There are three central pillars of UK law what are they?

Answer 39

o The right to silence
o The presumption of innocence
o The right to a fair trial

Question 40

How can different alcohol samples be taken?

Answer 40

• Breathalyser
• Blood sample
• Urine sample

Question 41

History of breath alcohol testing

Answer 41

• Before the police can use a device, it has to be “of a type, approved by the Secretary of State”
• The first screening devices were type approved in 1968
• The first electronic screening devices were type approved in 1981
• The first evidential breath testing devices were approved in 1983

Question 42

Samples for alcohol taken under the Road Traffic Act (and similar legislation) are either…

Answer 42

o Breath (screening and evidential)
o Blood (evidential)
o Urine (evidential)

Question 43

Main “preliminary” sample under s(6)RTA
Preliminary tests are specified as:

Answer 43

 Preliminary breath test
 Preliminary drug test (“saliva” or sweat)
 Preliminary impairment test

Question 44

Whats “Tube and bag” chemistry ?

Answer 44

• This relies on a colour change generated from the change in the oxidation state of chromium
• The tube is filled with crystals of acidified potassium dichromate [chromium(VI)]
• When an oxidising agent (in this case ethanol) is passed over the crystals the oxidation state of chromium changes to chromium(III).
• This gives rise to the colour change orange to green.
• **2Cr2O72- + 3C2H5OH + 16H+ → 4Cr3+ + 3CH3COOH + 11H2O
  **

Question 45

What is fuel cell chemistry?

Answer 45

Question 46

Usually after a positive screening breath test (or a refusal to provide a preliminary sample of breath), the motorist will be required to provide what? What will then happen next?

Answer 46

two specimens of breath for an evidential test.

If, for whatever reason (except an outright refusal), the specimens of breath could not be provided, the legislation then allows for blood or urine specimens to be provided instead.

At this stage, it is the officer’s choice of whether blood or urine specimens should be required. It must be the officer’s choice, and they cannot be directed towards one type of specimen or another.

Question 47

What are some requirements of a breath test?
How can they do all of these things?

Answer 47

o Accurate
o Specific
o Robust
o Ensure they measure “deep lung air”
o Avoid analysing “Mouth Alcohol”
o “Policeman proof”

So how do they do all of those things ?
Based on Infra-red analysis

Question 48

How is IR analysis used?

Answer 48

Question 49

Taking blood samples will differ as to whether in a hospital or not, what happens if not at a hospital?

Answer 49

o The requirement to provide a sample of blood must be made at a police station (there is no legal restriction on where the sample must be taken)
o The sample may be taken by a “healthcare professional” (nurse, paramedic)
o MUST be one sample split into two

Question 50

Taking blood samples will differ as to whether in a hospital or not, what happens if are at a hospital?

Answer 50

o It must be taken by a “medical practitioner” (i.e. a Doctor) and not a “healthcare professional” – and normally a “Forensic Medical Practitioner”
o However, it cannot be the same Doctor who is in charge of the primary care of the motorist – however this Doctor must agree that a sample can be taken

Question 51

What happens if there is an unconscious driver and tyou need a blood sample?

Answer 51

o Defined as “medically unable to give consent”
o A sample is taken (as per the normal Hospital procedures), but when (if…) the driver regains consciousness, they are asked if they consent to the sample being analysed.
o If they do not give consent, they are charged with “failing to provide…”

Question 52

How is a urine sample obtained for BAC analysis?

Answer 52

• The motorist must provide two specimens of urine. The first is taken and discarded, the second is split into two, and one portion offered to the motorist
• Both specimens should be supplied within an hour of the requirement being made
• The intention is that the bladder should be fully emptied on each occasion
• Caselaw covers situations where catheters are fitted

Question 53

The technique for the analysis of blood and urine for alcohol needs to be what?

Answer 53

o Quick
o Accurate and precise
o Cheap (or at least not expensive…)
o Specific
o Repeatable and reproducible

Question 54

Whats the most used technique for the analysis of blood and urine for alcohol?

Answer 54

The most used technique is “Headspace Gas Chromatography” (HS-GC)

Question 55

Why “Headspace” ?

Answer 55

o Blood and urine samples contain many different components which will quickly destroy any GC column

o Therefore, we only inject the volatile vapour which contains: water vapour, ethanol, (acetone), (other alcohols)

Question 56

How does HS-GC work?

Answer 56

• A known amount of sample is added to a known amount of “Internal Standard”
• The Internal Standard should be chemically similar to the compound of interest, but not expected to be found in blood
• Usually either propan-1-ol or propan-2-ol are chosen
• The first few samples are certified standards
• The ratio of ethanol to Internal Standard for these certified standards gives a “calibration curve”
• The ratio of ethanol to Internal Standard for blood or urine samples is read off the calibration curve to give the amount of ethanol present in the sample

Question 57

When analysing alcohol, what are some PM considerations?

Answer 57

o Postmortem diffusion of alcohol from the gut can falsely elevate the BAC

o Postmortem blood can have a much higher glucose concentration of 7x to 10x that of antemortem blood

o Postmortem blood is not sterile. Some studies have shown that over half of postmortem blood samples were found to contain bacteria and fungi

o High glucose concentrations combined with bacteria/fungi/yeast found in postmortem blood makes an ideal environment for the production of alcohol

o Other samples such as urine and vitreous humor are more stable than blood and can also be used with the results from blood samples to indicate putrefaction

Question 58

There are 5 main types of calculation – all use the same type of arithmetic, but they are for different purposes. Name and briefly describe each

Answer 58

1. Back calculation
o Where there is a delay between the time of driving and the taking of a sample, the prosecution (but not the defence) are able to carry out a back calculation to determine the alcohol level at the time of driving

2. Post-incident drinking (the “hip flask defence”)
o This is a defence to the per se offence in that the defendant would have been under the legal limit at the time of the offence but had subsequently drunk alcohol before a sample was taken.

3. The “laced drinks” defence
o This is where the defendant claims that they had unintentionally consumed alcohol without knowing it (for example where they had been supplied stronger drinks than they had asked for), and therefore believed they were below the legal limit at the time of driving

4. “Time to driving”
o This is specifically a defence to “being in charge…” where the defendant tries to show that although they were over the legal limit when tested, they would have been under the legal limit by the time that they drove the vehicle
o Note: The prosecution needs to prove “likelihood of driving”, which is not necessarily the same as when the defendant “intended to drive”

5. “Claimed drinking pattern”
o This isn’t a defence per se
o It is one of the most common calculations – but it has limited use.
o It relies on a famous piece of caselaw (Cracknell v Willis [1988] AC 450) where the motorist is entitled to submit evidence of what they had drunk
o However,…

Question 59

What do all of the 5 calculations require?

Answer 59

o Amount of alcohol consumed
o The drinking pattern (start and finish times)
o The height and weight of the motorist
o The gender of the motorist
o The time that the incident occurred
o The time that the evidential specimen was taken

Question 60

How can the calculations be further refined?

Answer 60

o A detailed drinking pattern
o The age of the defendant
o The presence (or absence) of food in the stomach

Question 61

Why is the pattern and duration of drinking so important?

Answer 61

Example:
o “I have only drunk four pints since lunchtime, and it’s 23:00 now”
and
o “I had one pint between 12:00 and 13:00, and three pints between 20:00 and 22:00, and it’s 23:00 now”

Second is better

Question 62

Why is knowing gender of the individual critical for alcohol calculation?

Answer 62

• The gender of the defendant is critical due to the distribution of alcohol in the body
• Alcohol is eventually distributed equally throughout all of the water in the body
• Assuming the same height and weight, a woman will have more fat (and hence less water) than a man
• Therefore, for a given amount of alcohol, the woman will have a higher blood alcohol concentration

Question 63

• There are several “factors” which give an estimation of the percentage of water in the body, the most well-known is what?
  What is this value for men and women?

Answer 63

Widmark factor

The mean Widmark factor for men is 0.68, and for women is 0.56

Question 64

There are several “factors” which give an estimation of the percentage of water in the body, the most well-known is the Widmark factor. Whats another example?

Answer 64

o There are other factors sometimes quoted (for example Forrest, Watson), but the differences between these other factors are generally small, and have little overall effect to the ranges quoted at the end of any calculation

Forrest Factor
o This is the factor which is recommended by UKIAFT to be used in all calculations.
o It uses:
 Gender
 Weight
 Height
to determine a more “personal” factor

Question 65

How to calculate the Forrest Factor?

Answer 65

Question 66

Why will the time that drinking started and finished have an effect?

Answer 66

o Alcohol starts to be absorbed almost immediately
o Alcohol will continue to be absorbed for a significant time after drinking stops. If you do a calculation based on samples taken too soon after drinking finishes you may get a wrong (and hence misleading) result.

Question 67

The theoretical peak concentration of alcohol is given by the simple formula…

Answer 67

c = a x 100/(p x r)

c = peak alcohol concentration in blood (mg/100ml)
a = total mass of alcohol taken (in grams)
p = the weight of the defendant (in kilograms)
r = appropriate Widmark factor

Question 68

Whats the normal quoted range for alcohol elimination from the blood?

Answer 68

9mg/100ml/hour to 29mg/100ml/hour

The figure normally used in calculations is 19mg/100ml/hour

Question 69

Calculations are normally carried out on blood alcohol levels, how do we convert the following:
Breath –> blood alcohol
Blood –> breath alcohol
Urine –> blood alcohol
Blood –> urine alcohol

Answer 69

Breath –> blood alcohol: x2.3 (and change units)
Blood –> breath alcohol: /2.3
Urine –> blood alcohol: /1.3375
Blood –> urine alcoho: x1.3375

If at any point the calculated blood alcohol concentration falls to zero, you need to take this into account and adjust the rest of your calculation accordingly

If the blood alcohol concentration falls below 20mg/100ml, you cannot use a linear elimination model

Question 70

How to approach blood alcohol calculations

Answer 70

o List your assumptions (Factor used (Widmark, Forrest, Watson, etc) alcoholic strength of drinks, volume consumed if not stated, timeframes if not obvious…)
o Estimate the peak alcohol level from drink #1
o Take off any eliminated alcohol until drink #2 was consumed
o Repeat for all drinks
o This will give a range of blood alcohol levels at the time of the evidential test
o Convert the blood alcohol levels to breath (or urine) alcohol levels if appropriate

Question 71

**Example 1 **
Male, 39 years old
Height = 172cm
Weight = 91kg
Time of incident = 23:28
Blood specimen = 03:00
Blood result = not less than 193mg/100ml

Pre-incident drinking: No alcohol before driving
Post-incident drinking: Vodka 37.5% vol 350ml (start= 23:28, finish= 23:33) and Can of beer 7% vol 250 ml (start=23:28, finish= 23:33)

Answer 71

• Alcohol calculations assumption
  o Drank a whole 350ml bottle of vodka
  o The vodka had an ABV of 37.5%
  o Drank a full 250ml can of beer
  o The beer had an ABV of 7%
• Alcohol calculations approach
  o Check all critical timings first
  o Work out how much ethanol (in grams) was consumed for each drink
  o Carry out a forward calculation
  o Check timings for back-calculation
  o Carry out a hip-flask calculation
  o Any other additional comments ?
• Alcohol calculations
  o Determination of mass of ethanol
  (Volume of drink) x (%ABV/100) = volume of ethanol
  (Volume of ethanol) x 0.789 = mass of ethanol
  (Repeat for each drink)
• Mass of ethanol in 350ml of vodka
  (350) x (37.5/100) = 131.25 mls
  0.789 = 103.55625 grams
• Mass of ethanol in 250ml of 7% ABV beer
  (250) x (7/100) = 17.5 mls
  17.5 x 0.789 = 13.8075 grams
• So, the total mass of ethanol consumed is:
  103.55625 + 13.8075 = 117.36375 grams (can assume for this is a single drink as start time for both are the same, cannot do this is have different start times)
• Next, we need to work out the time between ingestion and the evidential specimen
  23:28 to 03:00 = 3+(32/60) hours = 3.533 hours
• Using the Widmark factor for a male, we get:
  c = a x 100/(p x r)
  c = 117.36375 x 100/(91 x 0.68)
  c = 189.66 mg/100ml
• From the peak alcohol level, we need to account for the elimination:
  Lowest rate = 9 x 3.533 = 31.797mg/100ml
  Middle rate = 19 x 3.533 = 67.127mg/100ml
  Highest rate = 29 x 3.533 = 102.457mg/100ml
• This gives a range of values of:
  189.66 – 102.457 = 87.203mg/100ml
  189.66 – 67.127 = 122.533mg/100ml
  189.66 – 31.797 = 157.863mg/100ml
• Normal rounding gives us a “most likely” figure of 123mg/100ml within a range from 87 to 158mg/100ml
• Normal rounding gives us a “most likely” figure of 123mg/100ml within a range from 87 to 158mg/100ml
• This is not consistent with the measured value of 193mg/100ml.
• So, what can you say…?
  o He must have consumed more alcohol than he claimed

**Back calculation- based on above example **
* This calculation starts from the measured breath alcohol concentration and calculates back to the time of the incident. It considers any alcohol which may have been consumed after the incident and the alcohol which would have been naturally eliminated in the time between the incident and the time the breath sample was taken.
* Alcohol back calculations assume that the individual stopped drinking one hour before the time to which the back calculation is made. Where this is not so the calculation may overestimate the breath alcohol concentration.
* The measured value was 193mg/100ml
* The amount consumed was 189.66mg/100ml
* The time between the incident and the evidential test was 3.533 hours
* So, to back-calculate to the time of the incident, take the measured value, subtract the post-incident drinking, and add on the amount naturally eliminated:
193 – 189.66 + 102.457 = 105.797
193 – 189.66 + 67.127 = 70.467
193 – 189.66 + 31.797 = 35.137
* Again, this would normally be reported as a range:
* If the declared post-incident drinking pattern is true then at 23:24, the time of the road traffic incident, I would expect Mr XXXX’s blood alcohol concentration to have been about 70 milligrams per 100 millilitres (within a range from 35 to 106 milligrams per 100 millilitres)

“Hip flask”- based on above calculation
* This calculation addresses the ‘hip-flask’ situation but does not additionally back calculate to the time of the incident. The calculation subtracts the contribution of any post-incident drinks from the measured blood alcohol concentration and indicates what it would have been had the driver not consumed alcohol after the incident.
* The measured value was 193mg/100ml
* The amount consumed was 189.66mg/100ml
* This means that the measured alcohol level would have been 193 – 189.66 = 3mg/100ml had he not consumed alcohol after driving.
* Again, what can we say…?

Question 72

Example 2
Male, 56 years old
Height = 5’5” = 1.65 metres
Weight = 10½ stone = 66.68 kilograms
Time of incident = 19:30
Breath specimens = both at 21:00
Breath result = 74µg/100ml and 76µg/100ml

Defendent states he drank one double whiskey before driving, drove to a shop and had an altercation with a male outside. The defendant got back in his care to drive off and male took his car keys from the car, defendent fearing being assaulted drank whiskey sitting in the car. police called.

Pre-incident drinking: 1x double whiskey bells (start= 6pm, finish= 6pm)

Post-incident drinking: 5-6 mouthfuls of whiskey bells (start= 7:30pm, finish= 7:30pm)

Answer 72

• Assumptions
  o A double whisky has a volume of 50 millilitres
  o Bells whisky has an ABV of 40%
  o The driver consumed six “mouthfuls” of whisky
  o Each “mouthful” of whisky has a volume of 25mls
• Approach
  o Check all critical timings first
  o Work out how much ethanol (in grams) was consumed for each drink
  o Carry out a forward calculation
  o Check timings for back-calculation
  o Carry out a hip-flask calculation
  o Any other additional comments ?

* Mass of ethanol in a double whisky
50 x (40/100) = 20 mls
20 x 0.789 = 15.78 grams

• Mass of ethanol in six x 25ml whiskies
  (6 x 25) x (40/100) = 60 mls
  60 0.789 = 47.34 grams
• So, the mass of pre-incident ethanol consumed is: 15.78 grams
• Next, we need to work out the alcohol eliminated between ingestion and the next drink
  18:00 to 19:30 = 1½ hours = 1.5 hours
• **Pre-incident drinking **
  o Using the Widmark factor for a male, we get:
  c = a x 100/(p x r)
  c = 15.78 x 100/(66.68 x 0.68)
  c = 34.80 mg/100ml

o From the peak alcohol level, we need to account for the elimination:
Lowest rate = 9 x 1.5 = 13.5mg/100ml
Middle rate = 19 x 1.5 = 28.5mg/100ml
Highest rate = 29 x 1.5 = 43.5mg/100ml

o This gives a range of values of:
34.80 – 13.5 = 21.30 mg/100ml
34.80 – 28.5 = 6.30 mg/100ml
34.80 – 43.5 = zero mg/100ml
o Now we need to add on the post-incident drinks and take off the eliminated alcohol until the evidential specimen.

• **Post-incident drinking **
  o Using the Widmark factor for a male, we get:
  c = a x 100/(p x r)
  c = 47.34 x 100/(66.68 x 0.68)
  c = 104.406 mg/100ml
• So the peak alcohol concentration is:
  (Lowest rate) 21.3 + 104.406 = 125.706mg/100ml
  (Middle rate) 6.3 + 104.406 = 110.706mg/100ml
  (Highest rate) 0 + 104.406 = 104.406mg/100ml
• Now we need take off the eliminated alcohol until the evidential specimen.
• Now we need to take off the eliminated alcohol until the evidential specimen.
• 19:30 to 21:00 = 1.5 hours
• Post-incident drinking BAC = 104.406mg/100ml
• From the peak alcohol level, we need to account for the elimination:
  Lowest rate = 9 x 1.5 = 13.5mg/100ml
  Middle rate = 19 x 1.5 = 28.5mg/100ml
  Highest rate = 29 x 1.5 = 43.5mg/100ml
• This gives a range of values of:
  125.706 – 13.5 = 112.206mg/100ml
  110.706 – 28.5 = 82.206mg/100ml
  104.486– 43.5 = 60.986mg/100ml
  105.
• These are blood alcohol levels, so we need to convert them to breath alcohol levels (divide by 2.3)
• This gives a range of values of:
  112.206mg/100ml BAC = 48.78µg/100ml BrAC
  82.206mg/100ml BAC = 35.74µg/100ml BrAC
  60.986mg/100ml BAC = 26.52µg/100ml BrAC
  61.
• Normal rounding gives us a “most likely” figure of 36µg/100ml within a range from 27 to 49µg/100ml
• This is not consistent with the measured value of 74µg/100ml.
   Based on drinking pattern must have drunk more alcohol than assumed

Back calculation
* This calculation starts from the measured breath alcohol concentration and calculates back to the time of the incident. It takes into account any alcohol which may have been consumed after the incident and the alcohol which would have been naturally eliminated in the time between the incident and the time the breath sample was taken.
* Alcohol back calculations assume that the individual stopped drinking one hour before the time to which the back calculation is made. Where this is not so the calculation may overestimate the breath alcohol concentration.
* The measured value was 74ug/100ml
* A BrAC of 74ug/100ml = a BAC of 170.2mg/100ml
* The amount consumed was 104.406mg/100ml
* The time between the incident and the evidential test was 1.5 hours
* So, to back-calculate to the time of the incident, take the measured value, subtract the post-incident drinking, and add on the amount naturally eliminated:
170.2 – 104.406 + 13.5 = 79.294 (34ug/100ml)
170.2 – 104.406 + 28.5 = 94.294 (41µg/100ml)
170.2 – 104.406 + 43.5 = 109.294 (48µg/100ml)
* Again, this would normally be reported as a range:
If the declared post-incident drinking pattern is true then at 23:24, the time of the road traffic incident, I would expect Mr XXXX’s breath alcohol concentration to have been about 41 micrograms per 100 millilitres (within a range from 34 to 48 micrograms per 100 millilitres)

“Hip flask”
* The measured value was 74µg/100ml (170.2mg/100ml)
* The amount consumed was 104.406mg/100ml
* This means that the measured alcohol level would have been 170.2 – 104.406 = 65.795mg/100ml (29ug/100ml) had he not consumed alcohol after driving.
* Again, what can we say…?

Hip flaks should always be below the range you get for the back calculation