Scientific Overview

Absorption Rates

Ethanol is absorbed primarily in the small intestine. Although there is some absorption from the stomach, it is significantly slower than that from the intestine. Accordingly, the presence of food in the stomach will delay the absorption of ethanol. Thus, the resulting peak alcohol levels will generally be lower for most drinking patterns. DUI Pro uses the following absorption rates as default settings:

These rates may be modified.

Higher ethanol concentrations in the gastrointestinal tract cause a greater concentration gradient and therefore hasten the rate of absorption. The absorption process continues until the alcohol concentration in the blood and that in the gastrointestinal tract are at equilibrium.

Once ethanol reaches the systemic circulation it is immediately distributed to other body compartments at a rate proportional to the blood now to that area and is eventually distributed equally to total body water. Because the brain receives a rapid blood now, high concentrations in the brain are achieved rapidly. Deitrich, Richard, Palmer, John D. Human Pharmacology, Molecular to Clinical. , pg. 426 (Mosby, 1994).

Peak blood-alcohol levels can vary between different types of alcoholic beverages. The following results were published in B. O'Neill, A.F. Williams & KM. Dubowski, Variability in Blood Alcohol Concentration: Implications for Estimating Individual Results, 44:2 J. Stud. on Alcohol 228 (1983):

Drink	Average Peak BAC%	Time to Peak
Beer	0.093% (w/v)	40 minutes
Champagne	0.094% (w/v)	52 minutes
Mixed Whiskey	0.091 % (w/v)	37 minutes
Straight Whiskey	0.102% (w/v)	35 minutes

---

Blood Alcohol Level and Visible Intoxication

BAC	% Viewed as Drunk
0 to .05	10%
.051 to .010	34%
.101 to .150	64%
.151 to .200	86%
.201 to .250	96%
.251 to .300	99%
.301 to .350	99%
.351 to .400	89%
Above .400	100%

Source: R. Harger, ch. 4,

Ethyl Alcohol, in 2 Toxicology 110 (Academic Press 1961)

---

Concentration Expression

The forensic analysis of ethanol concentrations are usually expressed as a percentage weight per volume. For example, a blood-alcohol level of 0.08% refers to 0.08 grams of ethanol per 100 cubic centimeters of blood.

---

Distribution Constants

The distribution of ethanol in the body is governed by partitioning between water and fat.  As fat constitutes a higher proportion of the body weight in women than in men, the resultant volume of distribution of ethanol in women is lower than that of men. Accordingly, absorption of a given amount of ethanol will result in a higher blood-alcohol level in women than in men of equal weight. This difference is further enhanced as men typically weight more than women. (Textbook of Pharmacology, Smith, Cedric, M.D. and Reynard, Alan, Ph.D., Page 251-252, Harcourt Brace Jovanovich, Philadelphia (1992)). The original values proposed by Widmark were 0.68 for men and 0.55 for women. E.MP. Widmark, Principles & Applications of Medicalegal Alcohol Determinations (Scitran, Santa Barbara, CA, trans.)(Biomedical Pubs.: Davis, CA 1981).  More lean, muscular subjects will have a higher "r" value while fatter or more flaccid subjects will have a lower "r" value. P.E. Watson published the following values for "r" in Prediction of Blood Alcohol Concentration in Human Subjects: Updating the Widmark Equation, 42:7 J. Stud. on Alcohol 547 (1981).



Dubowski found a range of 0.73 +/- 0.067 (S.D) for male subjects and 0.66 +/- 0.082 (S.D.) for female subjects (K.M. Dubowski, Absorption, Distribution and Elimination of Alcohol: Highway Safety Aspects, J. Stud. on Alcohol 95-108 (Supp. No. 10 1985). By default DUI Professional calculates the elimination minimum and maximum to one standard deviation. This encompasses 68% of the population and is consistent with most interpretations of the clear and convincing standard.  For criminal cases, the settings may be adjusted to encompass 95% of the population by spanning two (2) standard deviations.  This is consistent with the higher standard of reasonable doubt.  Thus, for two standard deviations:





DUI Professional combines the minimum "r" distribution constant with the maximum elimination rate to achieve the minimum blood alcohol level. Conversely, the maximum "r" distribution constant is factored with the minimum elimination rate to achieve the maximum blood alcohol level.
REFERENCE: K Dubowski Human Pharmacokinetics of Ethanol. I. Peak Blood Alcohol Concentrations and Elimination in Male and Female Subjects, 5:4 Alcohol Technical Rep. S63 (1976).

---

Dubowski's "r" Values

K. Dubowski published the following values in Human Pharmacokinetics of Ethanol. I. Peak Blood Alcohol Concentrations and Elimination in Male and Female Subjects, 5:4 Alcohol Technical Rep. 55-63 (1976):

Dubowski's values are used as the default settings in DUI Professional.

---

Elimination Rate

Alcohol is primarily eliminated by the liver by enzymatic oxidation. Less than 10% is excreted from breath, perspiration and urine. In most calculations, the standard elimination rate for most individuals is 0.015% per hour. However, this rate may vary between individuals. Studies by Widmark, Dubowski and Watson have all confirmed a mean 0.015% elimination rate.

In a study by Winek and Murphy (C.L. Winek & K.L. Murphy, The Rate and Kinetics Order of Ethanol Elimination, 25 Forensic Sci. Int'; 159-166 (1984), they found the following elimination rates:

• Non-drinkers ( < 6 ounces EtOH/month) = 0.012% per hour +/- 0.004%
• Social drinkers ( 6-30 ounces EtOH/month) = 0.015% per hour +/- 0.004%
• Alcoholics ( > 30 ounces EtOH/month) = 0.030% per hour +/- 0.009%

As default values, DUI Professional uses an average 0.015% per hour distribution rate spanning two standard deviations based on Dubowski's data. Thus, 95% of the population should fall within the following range:

DUI Professional combines the minimum "r" distribution constant with the maximum elimination rate to achieve the minimum blood alcohol level. Conversely, the maximum "r" distribution constant is factored with the minimum elimination rate to achieve the maximum blood alcohol level.

---

Elimination Rate Deviation

In a 1985 study by K.M. Dubowski, 134 adult men were studied in the post-absorptive state and reported an elimination rate of 0.01494% per hour (+/- 0.00450 standard deviations), with a range of values from 0.006 to 0.028% per hour.  This constitutes an average of approximately 0.015% per hour.  Sixty eight percent (68%) of the population would have a range between 0.01 to 0.019% EtOH elimination per hour.  About 95% of the population would have a range of 0.006 to 0.23%.  K.M. Dubowski, Absorption, Distribution and Elimination of Alcohol: Highway Safety Aspects, J. Stud. on Alcohol 95-108 (Supp. No. 10 1985).

---

Ethanol (uses)

Ethanol is used primarily as a social drug. It has limited therapeutic applications. Ethanol is used topically to lower elevated body temperature by promoting evaporation, as a rub to prevent pressure sores in bedridden patients, and sometimes by injection to produce irreversible nerve block or tumor destruction. Ethanol is also used to treat methanol and ethylene glycol poisonings, where it acts competitively to prevent the conversion of these alcohols to toxic intermediates until the unmetabolized parent compounds are removed from the body. Ethanol is rarely prescribed for its antianxiety and sedative properties and to stimulate appetite. Ethanol has been used to reduce the frothing in acute pulmonary edema resulting from left ventricular failure. Deitrich, Richard, Palmer, John D. Human Pharmacology, Molecular to Clinical., pg. 423 (Mosby, 1994).

---

Ethanol and Vehicular Accidents

Consumption of ethanol has a strong relationship to the frequency traffic fatalities. In excess of 50% of fatal automobile accidents involve at least one intoxicated driver. The probability of being involved in a vehicular accident rises in an exponential manner with blood alcohol levels.

---

Ethanol weight versus volume

Total ethanol (EtOH) is automatically calculated in the drink settings screen. This value represents the ethanol content by volume, not by weight. DUI Professional translates the volume into weight by ethanol later in the calculations.

---

Ethanol's Effect (generally)

Like general anesthetic agents, ethanol depresses all areas and functions of the brain. Ethanol is described as a disinhibitor or euphoriant. Higher integrative areas of the brain are effected first. Thought processes, fine discrimination, judgment and motor function are sequentially impaired. These effects may be observed with blood ethanol levels of 0.05% (50 mg/dl) or lower. As blood ethanol concentration increases to 0.10%, errors in judgment are frequent, motor systems are impaired, and responses to complex auditory and visual stimuli are altered. Patterns of involuntary motor action are affected. From 0.15% to 0.20%, reactions times are increased and the individual may become extremely loud, incoherent and emotionally unstable. From 0.20% to 0.30%, intoxicated individuals frequently experience periods of amnesia or 'blackout," with failure to recall events occurring at that time.

---

Weight (body)

DUI Professional calculates the body weight of the subject to determine the expected blood-alcohol level. Subjects with a higher body weight will have a lower blood-alcohol level given the same amount of alcohol.

---

Widmark's Value

One of the most common methods of calculating an expected blood-alcohol level is to utilize the 'Widmark' equation. The Widmark equation relates the amount of ethanol absorbed into the bloodstream to body weight and blood alcohol content. It is expressed as:

A = WrC (or C = A/Wr)

where

• A = weight alcohol (ounces)
• W = weight of person (ounces)
• r = distribution constant (the IMdmark value)
• C = blood alcohol content expressed as a decimal.

The distribution constant ("r") is a measure of the concentration of alcohol in the body as a whole, compared to the alcohol concentration in the blood. The original values proposed by IMdmark were 0.68 for men and 0.55 for women. E.M.P. Widmark, Principles & Applications of Medicalegal Alcohol Determinations (Scitran, Santa Barbara, CA, trans.)(Biomedical Pubs. : Davis, CA 1981). More recent work suggests slightly higher values of 0.73 and 0.66 for men and women respectively.

---