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Encyclopedia > Blood alcohol

Blood alcohol content (or blood alcohol concentration), often abbreviated BAC, is the concentration of alcohol in blood, measured, by volume, as a percentage. For example, a BAC rating of 0.20 means 1 part per 500 in an individual's blood is alcohol. In many countries, the BAC is measured and reported as milligrams of alcohol per 100 milliliters of blood (mg/100ml). Ethyl alcohol, also known as ethanol or grain alcohol, is a flammable, colorless chemical compound, one of the alcohols that is most often found in alcoholic beverages. ... Red blood cells (erythrocytes) are present in the blood and help carry oxygen to the rest of the cells in the body Blood is a circulating tissue composed of fluid plasma and cells (red blood cells, white blood cells, platelets). ...


Number of drinks consumed is a poor measure of intoxication, because of variation according to body weight. One drink (unit of alcohol) will increase the average person's BAC to roughly 0.04, but there is much variation according to body weight, gender and body fat percentage. Furthermore, neither BAC nor the number of drinks consumed are necessarily accurate indicators of the level of impairment. Individual alcohol tolerance varies, and can be affected by genetic or nutritional factors, drugs, other degrees of impairment, and long-term heavy drinking. A glass of red wine contains about one unit of alcohol In the UK a system of units of alcohol is employed for an approximate measure of the amount of alcohol in different drinks. ...


Alcohol content in blood can be directly measured by a hospital laboratory. More commonly, for law enforcement purposes, BAC is estimated from breath ethanol content measured with a machine commonly referred to as a Breathalyzer (even though that is just the trademark of one manufacturer of the devices). A breathalyzer (or breathalyser) is a device containing a spectrophotometer that is used by police forces to detect the amount of alcohol in ones breath during traffic stops. ...


For purposes of law enforcement, BAC is used to define intoxication and provides a rough measure of impairment. Although degree of impairment may vary among individuals with the same BAC, the BAC has the advantage of being simpler to measure objectively, and therefore harder to contest, than impairment of driving.


Most countries disallow operation of motor vehicles and heavy machinery at prescribed levels of BAC, which vary both by country and by situation. In Sweden, driving with a BAC rate of over 0.02 is illegal. By contrast, the policies of the United States are much more liberal: In one state, a BAC rating as high as .099 is considered not intoxicated, though the federal government is pushing for a reduction of the limit to 0.08. In some states, drivers under 21 (the American drinking age) are considered legally impaired at lower levels (perhaps 0.02, or even a mere trace) as part of a zero tolerance policy. Zero tolerance is a strict approach to rule enforcement. ...


In Australia, the limit is 0.05 in most states and territories, and either 0.02 or zero for inexperienced drivers (learner drivers or those on probationary licenses). It is enforced by random breath testing. Drunk driving (drink driving in the UK) or drinking and driving is the act of operating a motor vehicle after having consumed alcohol (i. ...


Despite the liberal intoxication limits of many countries, one should not assume that driving with a BAC rating of, say, .079 is as safe as driving while sober. At a BAC rating of 0.05, the probability of a driver having an accident is more than four times its base level. Despite this, some drivers believe their driving actually improves with small amounts of alcohol. This assertion is false, because their ability to accurately judge the quality of their driving (measured by actual motor competence) deteriorates.


Unless a person has developed a high tolerance, a BAC rating of 0.20 represents very serious intoxication (most first-time drinkers would be passed out by about 0.15), and 0.35 represents potentially fatal alcohol poisoning. 0.40 is the accepted LD50, or lethal dose for 50% of adult humans. For a long-time, heavy drinker, those numbers can at least double. In extreme cases, individuals have survived BAC ratings as high as 0.914, but only with medical attention. In toxicology, the LD50 or colloquially semilethal dose of a particular substance is a measure of how much constitutes a lethal dose. ...


Metabolism and excretion

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 90 to 98% is metabolised, 1 to 3% is excreted in urine, and 1 to 5% evaporates through the breath. A very small proportion (less than 0.5%) is also excreted in the sweat, tears, etc. 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. (In fact in some males, alcohol dehydrogenase levels in the stomach are high enough that some metabolisation occurs even before the alcohol is absorbed.) Santorio Santorio (1561-1636) in his steelyard balance, from Ars de statica medecina, first published 1614 Metabolism (from μεταβολισμος(metavallo), the Greek word for change), in the most general sense, is the ingestion and breakdown of complex compounds, coupled with the liberation of energy, and the consequent generation of waste...


Metabolism is mainly by the group of six enzymes, collectively called alcohol dehydrogenase. These convert the ethanol into acetaldehyde (an intermediate that is actually more toxic than ethanol). The enzyme acetaldehyde dehydrogenase then converts the acetaldehyde into non-toxic acetyl-CoA. Neuraminidase ribbon diagram An enzyme (in Greek en = in and zyme = leaven) is a protein, or protein complex, that catalyzes a chemical reaction and also controls the 3D orientation of the catalyzed substrates. ... Alcohol Dehydrogenase Alcohol dehydrogenases are a group of dehydrogenase enzymes that occur in many organisms and facilitate the conversion between alcohols and aldehydes or ketones. ... Acetaldehyde, also known as ethanal, is a chemical compound, an aldehyde with formula CH3CHO and structure It is a highly reactive flammable liquid with a strong fruity smell. ... Categories: Biochemistry stubs | EC 1. ... Categories: Biochemistry stubs | Thiols ...


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; experienced male drinkers with a high body mass may process up to 30 grams (38 mL) per hour, but a more typical figure is 10 grams (12.7 mL) per hour. Persons below the age of 25, women, persons of certain ethnicities, and persons with liver disease, may process alcohol more slowly. Many east Asians (e.g. about half of Japanese) have impaired acetaldehye dehydrogenase; this 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 brew 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 oil), 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). Santorio Santorio (1561-1636) in his steelyard balance, from Ars de statica medecina, first published 1614 Metabolism (from μεταβολισμος(metavallo), the Greek word for change), in the most general sense, is the ingestion and breakdown of complex compounds, coupled with the liberation of energy, and the consequent generation of waste... A quantity is said to be subject to exponential decay if it decreases at a rate proportional to its value. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... Pharmacokinetics is a branch of pharmacology dedicated to the study of the time course of substances and their relationship with an organism or system. ... A hangover, medically termed veisalgia, is the after-effect following the consumption of large amounts of one drug or another. ... A hangover, medically termed veisalgia, is the after-effect following the consumption of large amounts of one drug or another. ... A very old bottle of Aspirin Aspirin or acetylsalicylic acid is a drug in the family of salicylates, often used as an analgesic (against minor pains and aches), antipyretic (against fever), and anti-inflammatory. ... The chemical compound furfural is an industrial chemical derived from a variety of agricultural byproducts, including corncobs, oat and wheat bran, and sawdust. ... Fusel alcohols, also sometimes called fusel oils, are higher order (more than two carbons) alcohols formed by fermentation and present in cider, mead, beer, wine, and spirits to varying degrees. ... The chemical compound trichloroethylene is a chlorinated hydrocarbon commonly used as an industrial solvent. ... For other meanings, see heavy metal The term heavy metal may have various more general or more specific meanings. ... Cimetidine is a histamine H2-receptor antagonist that inhibits the production of acid in the stomach. ... Cimetidine is a histamine H2-receptor antagonist that inhibits the production of acid in the stomach. ... Ranitidine is a histamine H2-receptor antagonist that inhibits stomach acid production, and commonly used in the treatment of peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD). ... Ranitidine is a histamine H2-receptor antagonist that inhibits stomach acid production, and commonly used in the treatment of peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD). ... Acetaminophen (USAN) or paracetamol (INN), is a popular analgesic and antipyretic drug that is used for the relief of fever, headaches, and other minor aches and pains. ... Tylenol is a popular American brand of pain reliever and fever reducer. ...


Test assumptions

Blood alcohol tests assume the individual being tested is average in various ways. For example, on average the ratio of BAC to breath alcohol content (the "partition ratio") is 2100 to 1. However, the actual ratio in any given individual can vary from 1700:1 to 2400:1, or even more widely. Thus a person with a true blood alcohol level of .08 but a partition ratio of 1700:1 would have a .10 reading on a Breathalyzer.


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. A urinalysis (or UA) is an array of tests performed on urine, usually used in medical diagnosis. ...


Another example is retrograde extrapolation, in which someone's BAC at the time of driving is found by extrapolating backwards from a later test. To estimate how much alcohol has been eliminated in the interim between driving and testing, one must know the rate of elimination. The rate for the average person is .015 percent per hour, although again this can vary.


In addition to the assumptions which affect chemical tests of BAC, there are similar assumptions in field testing. For example, the "horizontal gaze nystagmus" test estimates the BAC based on at what angle a suspect's eyes begin jerking. The BAC is obtained by subtracting the angle from 50 degrees; jerking at 35 degrees, for example, would mean the suspect has a BAC of .15 percent. Just as with the chemical tests, this is based on the angle for the average person, which doesn't necessarily apply to everyone. Nystagmus is rapid involuntary rhythmic eye movement, with the eyes moving quickly in one direction (quick phase), and then slowly in the other (slow phase). ...


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