Blood alcohol content

Updated on Sep 29, 2024

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LOINC 5639-0, 5640-8, 15120-9, 56478-1

Blood alcohol content (BAC), also called blood alcohol concentration, blood ethanol concentration, or blood alcohol level, is most commonly used as a metric of alcohol intoxication for legal or medical purposes. Blood Alcohol Content is the legal name for BAC but Blood Alcohol Concentration is sometimes used for simpler description.

Blood alcohol concentration is usually expressed as a percentage of ethanol in the blood in units of mass of alcohol per volume of blood or mass of alcohol per mass of blood, depending on the country. For instance, in North America a BAC of 0.1 (0.1% or one tenth of one percent) means that there are 0.10 g of alcohol for every dl of blood.

Estimated blood alcohol content by intake

To calculate estimated peak blood alcohol concentration (EBAC), a variation, including drinking period in hours, of the Widmark formula was used. The formula is:

E B A C = ( 0.806 × S D × 1.2 B W × W t − M R ⋅ D P ) × 10

where :

0.806 is a constant for body water in the blood (mean 80.6%),

SD is the number of standard drinks containing 10 grams of ethanol,

1.2 is a factor to convert the amount in grams to Swedish standards set by The Swedish National Institute of Public Health,

BW is a body water constant (0.58 for men and 0.49 for women),

Wt is body weight (kilogram),

MR is the metabolism constant (0.017) and

DP is the drinking period in hours.

10 converts the result to permillage of alcohol

Regarding metabolism (MR) in the formula; Females demonstrated a higher average rate of elimination (mean, 0.017; range, 0.014-0.021 g/210 L) than males (mean, 0.015; range, 0.013-0.017 g/210 L). Female subjects on average had a higher percentage of body fat (mean, 26.0; range, 16.7-36.8%) than males (mean, 18.0; range, 10.2-25.3%). Additionally, men are, on average, heavier than women but it is not strictly accurate to say that the water content of a person alone is responsible for the dissolution of alcohol within the body, because alcohol does dissolve in fatty tissue as well. When it does, a certain amount of alcohol is temporarily taken out of the blood and briefly stored in the fat. For this reason, most calculations of alcohol to body mass simply use the weight of the individual, and not specifically his/her water content. Finally, it is speculated that the bubbles in sparkling wine may speed up alcohol intoxication by helping the alcohol to reach the bloodstream faster. A study conducted at the University of Surrey in the United Kingdom gave subjects equal amounts of flat and sparkling Champagne which contained the same levels of alcohol. After 5 minutes following consumption, the group that had the sparkling wine had 54 milligrams of alcohol in their blood while the group that had the same sparkling wine, only flat, had 39 milligrams.

Examples:

80 kg male drinking 3 standard drinks in two hours:

E B A C = ( 0.806 ⋅ 3 ⋅ 1.2 ) / ( 0.58 ⋅ 80 ) − ( 0.015 ⋅ 2 ) = 0.032534483 ≈ 0.033 g / d L

70 kg woman drinking 2.5 standard drinks in two hours:

E B A C = ( 0.806 ⋅ 2.5 ⋅ 1.2 ) / ( 0.49 ⋅ 70 ) − ( 0.017 ⋅ 2 ) = 0.036495627 ≈ 0.036 g / d L

Note: This chart defines a drink as 14g of ethanol, while the formula defines a drink as 10g of ethanol.

Binge drinking

The National Institute on Alcohol Abuse and Alcoholism (NIAAA) define the term "binge drinking" as a pattern of drinking that brings a person’s blood alcohol concentration (BAC) to 0.08 grams percent or above. This typically happens when men consume 5 or more drinks, and when women consume 4 or more drinks, in about 2 hours.

Units of measurement

There are several different units in use around the world for defining blood alcohol concentration. Each is defined as either a mass of alcohol per volume of blood or a mass of alcohol per mass of blood (never a volume per volume). 1 milliliter of blood has a mass of approximately 1.06 grams. Because of this, units by volume are similar but not identical to units by mass. In the U.S. the concentration unit 1% w/v (percent mass/volume, equivalent to 10 g/l or 1 g per 100 ml) is in use. This is not to be confused with the amount of alcohol measured on the breath, as with a breathalyzer. The amount of alcohol measured on the breath is generally accepted as proportional to the amount of alcohol present in the blood at a rate of 1:2100. Therefore, a breathalyzer measurement of 0.10 mg/L of breath alcohol converts to 0.0001×2100 g/10dL, or 0.021 g/dL of blood alcohol (the units of the BAC in the United States). While a variety of units (or sometimes lack thereof) is used throughout the world, many countries use the g/L unit, which does not create confusion as percentages do. Usual units are highlighted in the table below.

Legal limits

For purposes of law enforcement, blood alcohol content is used to define intoxication and provides a rough measure of impairment. Although the degree of impairment may vary among individuals with the same blood alcohol content, it can be measured objectively and is therefore legally useful and difficult to contest in court. Most countries disallow operation of motor vehicles and heavy machinery above prescribed levels of blood alcohol content. Operation of boats and aircraft are also regulated.

The alcohol level at which a person is considered legally impaired varies by country. The list below gives limits by country. These are typically blood alcohol content limits for the operation of a vehicle.

Zero effective tolerance

It is illegal to have any measurable alcohol in the blood while driving in these countries. Most jurisdictions have a tolerance slightly higher than zero to account for false positives and naturally occurring alcohol in the body. Some of the following jurisdictions have a general prohibition of alcohol.

Australia—Learner drivers or those drivers with a Provisional/Probationary Licence

Bangladesh

Brazil

Brunei

Canada—new drivers undergoing graduated licensing in Ontario, British Columbia and Newfoundland and Labrador; drivers under the age of 22 in Manitoba, New Brunswick, Northwest Territories, Nova Scotia, Ontario, Saskatchewan, Quebec and in Alberta receive a 30-day suspension and 7-day vehicle seizure.

Colombia —Zero Alcohol Tolerance law is effective since December 2013

Czech Republic

Estonia

Fiji

Hungary

Israel—24 µg per 100 ml (0.024%) of breath (penalties only apply above 26 µg per 100 ml (0.026%) of breath due to lawsuits about sensitivity of devices used). New drivers, drivers under 24 years of age and commercial drivers 5 µg per 100 ml of breath.(0,005%)

Italy—drivers under the age of 21

Japan—drivers under the age of 20 because of not reaching legal drinking age.

New Zealand—drivers under the age of 20 and convicted drivers required to gain a zero-limit license.

Nepal

Oman

Pakistan

Paraguay

Romania (beyond 0.08% drivers will not only receive a fine and have their license suspended, the offense will also be added to their criminal records.)

Russian Federation (0% introduced in 2010, but discontinued in September 2013)

Saudi Arabia

Slovakia

Uruguay

United Arab Emirates

United States—drivers under the age of 21 because of not reaching legal drinking age.

0.02%

China

Netherlands (for drivers in their first five years after gaining a driving license)

Norway (road vehicles and sea vessels over 15 m), alternatively 0.1 mg/L of breath.

Poland

Puerto Rico

Sweden

Ukraine

0.03%

Belarus

Bosnia and Herzegovina (0.031%)

Chile

India (note: In the state of Kerala, a policy of zero tolerance has developed.)

Serbia

Japan

Russia (since September 2013)

0.04%

Lithuania (0.00% for car drivers in their first two years after gaining a driving license, motorcycle and truck drivers)

0.05%

Argentina (0.02% for motorbikes, 0.00% for truck, taxi, and bus drivers)

Australia (0.00% for Australian Capital Territory learner, provisional and convicted DUI drivers (changed down from 0.02% on December 1, 2010), 0.02% for truck/bus/taxi, 0.00% for learner drivers, provisional/probationary drivers (regardless of age), truck and bus drivers, driving instructors and DUI drivers in all other states)

Austria – no limit for pedestrians; 0.08% for cycling; 0.05% generally for cars <7,5 t (driving licence B) and motorbikes (A); but 0,01% during learning (for driver and teacher or L17-assistant), during probation period (at least the first 2 years) or up to the age of 20 (A1, AM, L17, F), trucks (C >7,5 t), bus (D), drivers of taxi and public transport

Belgium (also for cyclists)

Bulgaria

Canada: Alberta, British Columbia, Ontario, Manitoba, Newfoundland, Nova Scotia, New Brunswick—provincial offence. Drivers have not committed a criminal offense, however a 3-day licence suspension and 3-day vehicle seizure occurs.

Costa Rica

Croatia—professional drivers, driving instructors and drivers of the vehicle categories C1, C1+E, C, C+E, D, D+E and H; the limit for other drivers is 0.50 mg/g, but they do get an additional separate fine if they cause an accident while having a blood alcohol level between 0 and 0,50 mg/g

Denmark

Finland

France (0.025% for bus drivers)

Germany (0.0% for learner drivers, all drivers 18–21 and newly licensed drivers of any age for first two years of licence; also, if the BAC exceeds 0.03%, driving is illegal if the driver is showing changes in behavior ("Relative Fahruntüchtigkeit"))

Greece

Hong Kong

Iceland

Ireland (0.02% for learner drivers and professional drivers)

Israel 24 µg per 100 ml (0.024%) of breath (penalties only apply above 26 µg per 100 ml (0.026%) of breath due to lawsuits about sensitivity of devices used). This is equivalent to a BAC of 0.05. New drivers, drivers under 24 years of age and commercial drivers 5 µg per 100 ml of breath. This is equivalent to a BAC of 0.01.

Italy (0.00% for drivers in their first three years after gaining a driving license)

Latvia (0.02% for drivers in their first two years after gaining a driving license)

Luxembourg

Macedonia (0.00% for drivers in their first two years after gaining a driving license)

Netherlands (0.02% for drivers in their first five years after gaining a driving license)

New Zealand

Peru

Philippines (0.00% for taxicab and public transport drivers)

Portugal (0.02% for drivers holding a driver's licence for less than three years, professional drivers, and drivers of taxis, heavy vehicles, emergency vehicles, public transport of children and carrying dangerous goods).

Scotland

Slovenia (0.00% for drivers in their first two years after gaining a drivers licence, drivers under 21 and professional drivers, such as buses, trucks...)

South Africa

Spain (0.03% for drivers in their first two years after gaining a driving license and common carriers, such as buses, trucks...)

Switzerland (0.01% for drivers in their first three years after gaining a drivers licence and for driving instructors)

Thailand

Taiwan (breath alcohol limit decreased from 0.25 to 0.15 from 13 June 2013)

Turkey

0.06%

The Bahamas

0.07%

Honduras

0.08%

Canada Quebec (provincial law)

England and Wales (0.02% for operators of fixed-wing aircraft).

Malaysia (0.00 for Probationary Driving Licence holders)

Malta

Mexico

New Zealand Criminal offence

Norway (legal limit for sea vessels under 15 m)

Northern Ireland (The government of Northern Ireland intends to reduce the general limit to 0.05%.)

Puerto Rico (for drivers 21 years and older)

Singapore

United States—all states impose penalties for driving with a BAC of 0.08% or greater. Even below those levels drivers can have civil liability and other criminal guilt (e.g., in Arizona driving impairment to any degree caused by alcohol consumption can be a civil or criminal offense in addition to other offenses at higher blood alcohol content levels). Drivers under 21 (the most common U.S. legal drinking age) are held to stricter standards under zero tolerance laws adopted in varying forms in all states: commonly 0.01% to 0.05%. See Alcohol laws of the United States by state. Federal Motor Carrier Safety Administration: 0.04% for drivers of a commercial vehicle requiring a commercial driver's license and 0.01% for operators of common carriers, such as buses.

0.1%

Cayman Islands

Limits by country (BrAC: breath alcohol content)

In certain countries, alcohol limits are determined by the breath alcohol content (BrAC), not to be confused with blood alcohol content (BAC).

In Greece, the BrAC limit is 250 microgrammes of alcohol per litre of breath. The limit in blood is 0.50 g/l. The BrAC limit for drivers in their first two years after gaining a driving license and common carriers are more restricted to 100 microgrammes per litre of breath.

BrAC 250–400 = €200 fine.

BrAC 400–600 = €700 fine, plus suspension of driving license for 90 days (introduced in 2007)

BrAC >600 = 2 months imprisonment, plus suspension of driving license for 180 days, plus €1,200 fine

In Hong Kong, the BrAC limit is 220 microgrammes per litre of breath (as well as other defined limits)

In The Netherlands and Finland, the BrAC limit is 220 microgrammes of alcohol per litre of breath (μg/l, colloquially known as "Ugl").

In New Zealand, the BrAC limit is 250 microgrammes of alcohol per litre of breath for those aged 20 years or over, and zero (meaning illegal to have any measurable breath alcohol content) for those aged under 20 years.

In Singapore, the BrAC limit is 350 microgrammes of alcohol per litre of breath.

In Spain the BrAC limit is 250 microgrammes of alcohol per litre of breath and 150 microgrammes per litre of breath for drivers in their first two years after gaining a driving license and common carriers.

In England and Wales the BrAC limit is 350 microgrammes of alcohol per litre of breath (as well as the above defined blood alcohol content).

In Scotland the BrAC limit is 220 microgrammes of alcohol per litre of breath (as well as the above defined blood alcohol content).

Other limitation schemes

For South Korea, the penalties for different blood alcohol content levels include

0.01–0.049 = No penalty

0.05–0.09 = 100 days license suspension

>0.10 = Cancellation of car license.

Test assumptions

Blood alcohol tests assume the individual being tested is average in various ways. For example, on average the ratio of blood alcohol content to breath alcohol content (the partition ratio) is 2100 to 1. In other words, there are 2100 parts of alcohol in the blood for every part in the breath. However, the actual ratio in any given individual can vary from 1300:1 to 3100:1, or even more widely. This ratio varies not only from person to person, but within one person from moment to moment. Thus a person with a true blood alcohol level of .08% but a partition ratio of 1700:1 at the time of testing would have a .10 reading on a Breathalyzer calibrated for the average 2100:1 ratio.

A similar assumption is made in urinalysis. When urine is analyzed for alcohol, the assumption is that there are 1.3 parts of alcohol in the urine for every 1 part in the blood, even though the actual ratio can vary greatly.

Breath alcohol testing further assumes that the test is post-absorptive—that is, that the absorption of alcohol in the subject's body is complete. If the subject is still actively absorbing alcohol, their body has not reached a state of equilibrium where the concentration of alcohol is uniform throughout the body. Most forensic alcohol experts reject test results during this period as the amounts of alcohol in the breath will not accurately reflect a true concentration in the blood.

Metabolism and excretion

Alcohol is absorbed throughout the gastrointestinal tract, but more slowly in the stomach than in the small or large intestine. For this reason, alcohol consumed with food is absorbed more slowly, because it spends a longer time in the stomach. Furthermore, alcohol dehydrogenase is present in the stomach lining. After absorption, the alcohol passes to the liver through the hepatic portal vein, where it undergoes a first pass of metabolism before entering the general bloodstream.

Alcohol is removed from the bloodstream by a combination of metabolism, excretion, and evaporation. The relative proportion disposed of in each way varies from person to person, but typically about 95% is metabolized by the liver. The remainder of the alcohol is eliminated through excretion in breath, urine, sweat, feces, milk and saliva. Excretion into urine typically begins after about 40 minutes, whereas metabolisation commences as soon as the alcohol is absorbed, and even before alcohol levels have risen in the brain.

Alcohol is metabolized mainly by the group of six enzymes collectively called alcohol dehydrogenase. These convert the ethanol into acetaldehyde (an intermediate more toxic than ethanol). The enzyme acetaldehyde dehydrogenase then converts the acetaldehyde into non-toxic acetic acid.

Many physiologically active materials are removed from the bloodstream (whether by metabolism or excretion) at a rate proportional to the current concentration, so that they exhibit exponential decay with a characteristic halflife (see pharmacokinetics). This is not true for alcohol, however. Typical doses of alcohol actually saturate the enzymes' capacity, so that alcohol is removed from the bloodstream at an approximately constant rate. This rate varies considerably between individuals. Another sex based difference is in the elimination of alcohol. People under 25, women or with liver disease may process alcohol more slowly. False High (BAC) readings are related to patients with proteinuria and hematuria, due to kidney-liver metabolism and failure (for example, Hematuria 1+ protenuria 1+ )

Such persons have impaired acetaldehyde dehydrogenase, which causes acetaldehyde levels to peak higher, producing more severe hangovers and other effects such as flushing and tachycardia. Conversely, members of certain ethnicities that traditionally did not use alcoholic beverages have lower levels of alcohol dehydrogenases and thus "sober up" very slowly, but reach lower aldehyde concentrations and have milder hangovers. Rate of detoxification of alcohol can also be slowed by certain drugs which interfere with the action of alcohol dehydrogenases, notably aspirin, furfural (which may be found in fusel alcohol), fumes of certain solvents, many heavy metals, and some pyrazole compounds. Also suspected of having this effect are cimetidine (Tagamet), ranitidine (Zantac), and acetaminophen (Tylenol) (paracetamol).

Currently, the only known substance that can increase the rate of metabolism of alcohol is fructose. The effect can vary significantly from person to person, but a 100 g dose of fructose has been shown to increase alcohol metabolism by an average of 80%. Fructose also increases false positives of high BAC ratio readings in anyone with proteinuria and hematuria, due to kidney-liver metabolism.

Full stomachs

Alcohol absorption can be slowed by ingesting alcohol on a full stomach. Spreading the total absorption of alcohol over a greater period of time decreases the maximum alcohol level, decreasing the hangover effect. Thus, drinking on a full stomach or drinking while ingesting drugs which slow the breakdown of ethanol into acetaldehyde will reduce the maximum blood levels of this substance and thus decrease the hangover.

Carbonated beverages

Alcohol in carbonated beverages is absorbed faster than alcohol in non-carbonated drinks. Another study also confirmed this, conducted at the University of Surrey in the United Kingdom gave subjects equal amounts of flat and sparkling champagne which contained the same levels of alcohol. After 5 minutes following consumption, the group that had the sparkling wine had 54 milligrams of alcohol in their blood while the group that had the same wine, only flat, had 39 milligrams.

Stress

Being under stress causes alcohol to metabolize faster.

Retrograde extrapolation

Retrograde extrapolation is the mathematical process by which someone's blood alcohol concentration at the time of driving is estimated by projecting backwards from a later chemical test. This involves estimating the absorption and elimination of alcohol in the interim between driving and testing. The rate of elimination in the average person is commonly estimated at .015 to .020 grams per deciliter per hour (g/dl/h), although again this can vary from person to person and in a given person from one moment to another. Metabolism can be affected by numerous factors, including such things as body temperature, the type of alcoholic beverage consumed, and the amount and type of food consumed.

In an increasing number of states, laws have been enacted to facilitate this speculative task: the blood alcohol content at the time of driving is legally presumed to be the same as when later tested. There are usually time limits put on this presumption, commonly two or three hours, and the defendant is permitted to offer evidence to rebut this presumption.

Forward extrapolation can also be attempted. If the amount of alcohol consumed is known, along with such variables as the weight and sex of the subject and period and rate of consumption, the blood alcohol level can be estimated by extrapolating forward. Although subject to the same infirmities as retrograde extrapolation—guessing based upon averages and unknown variables—this can be relevant in estimating BAC when driving and/or corroborating or contradicting the results of a later chemical test.

Highest recorded blood alcohol level/content

There have been reported cases of blood alcohol content higher than 1%:

In March 2009, a 45-year-old man was admitted to the hospital in Skierniewice, Poland, after being struck by a car. The blood test showed blood alcohol content at 1.23%. The man survived but did not remember either the accident or the circumstances of his alcohol consumption.

In 1984 a 30-year-old man survived a blood alcohol concentration of 1,500 mg/100 ml (1.5%) after vigorous medical intervention that included dialysis and intravenous therapy with fructose.

In South Africa, a man driving a Mercedes-Benz Vito light van containing 15 sheep, allegedly stolen from nearby farms, was arrested on December 22, 2010, near Queenstown in Eastern Cape. His blood had an alcohol content of 1.6 g/100 ml (1.6%). Also in the vehicle were five boys and a woman who were also arrested.

In 2004, an unidentified Taiwanese woman died of alcohol intoxication after immersion for twelve hours in a bathtub filled with 40% ethanol. Her blood alcohol content was 1.35%. It was believed that she had immersed herself as a response to the SARS epidemic.

In Poland, a homeless man was found sleeping half-naked on January 28, 2011, in Cieszyn. His blood had an alcohol level of 1.024%. Despite the temperature of −10 °C and extremely high blood alcohol content, the man survived.

In December 2004, a man was admitted to the hospital in Plovdiv, Bulgaria, after being struck by a car. After detecting a strong alcohol odor, doctors at a hospital conducted a breath test which displayed the man's blood alcohol content at 0.914%. The man was treated for serious injuries sustained in the crash and survived.

In February 2005, French gendarmes from Bourg-en-Bresse, France, conducted a breath test on a man who had lost control of his car. He had an alcohol content of 0.976%. He was not injured in the accident but received a custodial sentence and his driving license was canceled.

In 1982, a 24-year-old woman was admitted to the UCLA emergency room with a serum alcohol concentration of 1.51% (1,510 mg/dL), corresponding to a BAC of 1.33%. She was alert and oriented to person and place. Serum alcohol concentration is not equal to nor calculated in the same way as blood alcohol content.

On 26 October 2012 a man from Gmina Olszewo-Borki, Poland, who died in a car accident, recorded 2.23%, however the blood sample was collected from a wound and thus possibly contaminated.

In 2013, on July 26 a 40-year-old man from Alfredówka, Poland, was found by Municipal Police Patrol from Nowa Dęba lying in the ditch along the road in Tarnowska Wola. At the hospital there was recorded that the man had 13.74 permille of alcohol in the blood (1.374%). The man survived.

In 1995, a man from Wrocław caused a car accident near his hometown. He had an alcohol content of 1.48% (14,8 permille); he was tested five times but all results were the same. He died a few days later of injuries from the accident.

References

Blood alcohol content Wikipedia

(Text) CC BY-SA

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