See also: Alcohol Bibliography
See also: Alcohol Impairment
See also: Alcohol Impairment Charts
See also: ETOH -- NIAAA Alcohol and Alcohol Problems Science Database.
See also: PubMed or MEDLINE-- is the National Library of Medicine's (NLM) bibliographic database.
See also: ICADTS for information on THE WIDMARK AWARD.

There appear to be a number of ways of calculating a person blood alcohol to a previous time. The literature uses these terms in reference to calculating backward: Widmarks, retrograde extrapolation, back calculation, regression analysis and ethanol elimination rate. Whatever it is called, the authors of these articles agree that the process cannot reliably be done with breath alcohol (Jones, Dubowski, et al), only blood alcohol concentrations.

There are various blood alcohol experts who maintain that one can do back calculation/Widmarks/regression analysis/ ethanol elimination rate if enough information is available. Among these published experts are: A. W. Jones, Mark Montgomery, A. R. Stowell, and Shajani and Dinn. 

Blood Alcohol Content for general background information on this subject. Note information in Wikipedia should be verified by other sources.
http://en.wikipedia.org/wiki/Blood_alcohol_concentration

Andreasson, R.; Jones, A. W.; The Life and work of Erik M. P. Widmark," AMERICAN JOURNAL OF FORENSIC MEDICINE AND PATHOLOGY (1996), 17 (3): 177-190.

Cassidy, F. H.; "Another nomogram for solving Widmark's equation for blood alcohol levels," JOURNAL OF THE FORENSIC SCIENCES SOCIETY (1984), 24: 557-558.

Cherpitel, Cheryl J.; Ye, Yu; Bond, Jason; Borges, Guilherme; "The causal attribution of injury to alcohol consumption: a cross-national meta-analysis from the emergency room collaborative alcohol analysis project." ALCOHOLISM: CLINICAL AND EXPERIMENTAL RESEARCH (2003), 27 (11): 1805-1812. " Pooled odds rations for both log-transfromed blood alcohol concentrations at the time of the emergency room visit and the amount of alcohol consumed in the 6 hr. before injury were positively predictive (1.19 and 1.80, respectively) and heterogeneous across studies. Effect size changed little when age and gender were controlled. When stratifying on reporting five or more drinks on an occasion during the last year (5+ yearly drinkers. The effect size of feeling drunk at the time of injury, controlling for the amount of alcohol consumed, was positively predictive (2.04) but heterogeneous across studies. Meta-analysis regression found the level to which alcohol is consumed in a detrimental pattern to be a significant predictor of blood alcohol concentration, and of the amount consumed and feeling drunk at the time of injury, on causal attribution, with a lower detrimental pattern level with a larger effect size. The association of acute use of alcohol on causal attribution may be affected by chronic use to some extent, but this association is negatively affected by the degree to which society exhibits harmful drinking patterns.

"Computing a BAC estimate," U. S. Department of Transportation, National Highway Traffic Safety Administration, October, 1994, 3 pages.
http://ntl.bts.gov/card_view.cfm?docid=5188 (Interestingly the U. S. Department of Transportation espouses BAC estimates using Widmarks and Watson's TBW (total body water.)

Detting, A,; Witte, S.; Skopp, G.; Graw, M.; Haffner, M. T.; "A regression model applied to gender-specific ethanol elimination rates from blood and breath measurement in non-alcoholics", INTERNATIONAL JOURNAL OF LEGAL MEDICINE (2009), 123 (5): 381-5. As elimination rates for alcohol are suggested to gender specific, a novel regression model has been applied to estimate those rates for both men and women using experimentally measured data from 81 female and 96 male volunteers described in previous papers. Breath alcohol measurements were done with the Alcotest 7110 evidential device and were coupled with concomitant sampling of venous blood. Statistical analyses involved use of a mixed linear model for blood alcohol concentration (BAC) and breath alcohol concentration (BrAC), respectively. The model takes regression lines for each test subject into account with an individual starting value (2 h after the end of drinking) and with an individual alcohol elimination rate per hour (coincidental effects). Further, the data was modeled so that an average alcohol elimination rate per hour could be estimated separately for both genders (constant effects). This enables us to methodically correctly estimate the back calculation. The elimination rates beta (60), which can be use for minimum and maximum back calculations for the BAC, were 0.115 g/kg/h and 0.260 g/kg/h, respectively, for women and 0.096 g/kg/h and 0.241 g/kg/h, respectively for men these figures widely deviate from gender-unspecific values commonly used in Germany (0.1 and 0.23 g/kg/h, respectively). The corresponding values for the BrAC were 0.061 mg/l/h and 0.124 mg/l/h for women and 0.049 mg/l/h and o.112 mg/l/h for men. The probability of an over-or underestimation of the abovementioned extreme values is 0.3% in each case.

Fagan, D.; Tiplady, B.; Scott, D. B.; "Effects of ethanol on psychomotor performance," BRITISH JOURNAL OF ANESTHESIOLOGY (1987), 59: 961-5.

Feldstein, A.: "The Metabolism of alcohol: on the validity of the Widmark equations, in obesity, and in racial and ethnic groups," JOURNAL OF STUDIES ON ALCOHOL (1978), 39 (5): 926-932. (Food, obese, and non WASP.)

Forrest, A. R. W.; "Commentary: Estimation of Widmark's factor," JOURNAL OF THE FORENSIC SCIENCES SOCIETY (1986), 26 (4): 249-252.) The author gives a case for using Watson's TBW formula with Widmark's r to calculate a BAC.)

Garriott, J.; "Forensic aspects of ethyl alcohol," CLINICS IN LABORATORY MEDICINE (1983), 3 (2): 385-396. (Widmark and retrograde calculations.)

Gullberg, Rod G., "Breath alcohol measurement variability associated with different instrumentation and protocols", "FORENSIC SCIENCE INTERNATIONAL (2003), 131 (1): 30-35.

Gullberg, R. G.; "Considering measurement variability when performing retrograde extrapolation of breath alcohol results," JOURNAL OF ANALYTICAL TOXICOLOGY (1994), 18 (2): 126-7.

Gullberg, R. G.; Jones A. W.; "Guidelines for estimating the amount of alcohol consumed from a single measurement of blood alcohol concentration: Reevaluation of Widmark's equation," FORENSIC SCIENCE INTERNATIONAL (1994), 69 (2) :119-130.

Horowitz, M.; Maddox, A.; Bochner, M; Wishart, J.; Bratasuik, R.; Collins, P.; Shearman, D.; "Relationship between gastric emptying of solid and caloric liquid meals and alcohol absorption," JOURNAL OF AMERICAN PHYSIOLOGY (1989), 257: G291-98. (Our observation that the rate of alcohol absorption was highest when the alcohol was consumed alone and lower when it was consumed with or after the solid meal is consistent with previous reports. Despite considerable inter individual variation in blood alcohol concentrations [which indicate the limitations of back calculation of blood alcohol concentrations] there was a close relationship between alcohol absorption and the rate of emptying.)

Hume, D. H., Fitzgerald, E. F.; "Chemical tests for intoxication. What do the numbers really mean?" ANALYTICAL CHEMISTRY, 57 (8): 876-86. (Two lawyers argue the demerits of Widmarks and alcohol elimination, this is based on breath alcohol, not blood.)

Jachau, K.; Sauer, S.; Krause, D.; Wittig, H., "Comparative regression analysis of concurrent elimination-phase blood and breath alcohol concentration measurements to determine hourly degradation rates", (FORENSIC SCIENCE INTERNATIONAL (2004), 143, (2-3): 115-120. (59 men, 391 breath alcohol tests, 2 hrs after drinking,.

Jones, A. W.; "Back-estimation of blood alcohol concentration (letter to the editor)," BRITISH JOURNAL OF CLINICAL PHARMACOLOGY (1993), 35: 669.

Jones, A. W.; "Inter individual variation in the disposition and metabolism of ethanol in healthy men," ALCOHOL (1984), 1 (5): 385-91. (Uses Widmark's to calculate BAC of 48 fasted men. 23 subjects peaked at 30 min., 14 at 60 min., 8 at 90 min., and 3 at 120 min. after start of drinking, 0.61 to 1.23 was the range for peak BAC. The elimination rate from blood was lower in those subjects with larger distribution volume. The results show that blood-ethanol parameters calculated according to Widmark's method have low inter subject variability when the dose of ethanol administered and the condition of the test subjects are carefully controlled.)

Jones, A. W.; "Widmark's equation: determining amounts of alcohol consumed from blood alcohol concentration," DWI JOURNAL (1986), p. 8-11.

Kalant, H.; Reed, T. E.; "Limitations of the Widmark calculation: a reply to Feldstein's critique," JOURNAL OF STUDIES ON ALCOHOL (1978), 39 (5): 933-936. (Widmark's and obesity.)

Krause, D.; Wehner, H. D., "Blood alcohol/congeners of alcoholic beverages", FORENSIC SCIENCE INTERNATIONAL (2004), 144 (2-3):177-183. Contents: detection of ethanol in blood, determination of breath ethanol, pharmacokinetics of ethanol, calculation of the ethanol concentration backwards to the offense time, calculation of the blood ethanol concentrations from the amount consumed ethanol/resorption deficit, ethanol consumption after offense, and the analysis of congener alcohols.

Lands, W.E.M.; "A Review of alcohol clearance in humans," ALCOHOL (1998), 15, (2): 147-160. ("The literature of the past 50 years consistently described time-dependent changes in BAL following ingestion or infusion. Generally, oral ingestion gives an initial rise in BAL that represents absorption from the intestine, peaking usually within 1 h. Then there follows an approximately linear decline in BAL with time (zero order kinetics) equivalent to about 3 mmol per minute for people with about 50 l of body water which is based on data from Jones et al. and resembles results in other reports (Derr, 1993, Wallgren, 1970, and Wilkinson, 1977)".

Lewis, K. O.; "Back calculation of blood alcohol concentration," BRITISH MEDICAL JOURNAL (1987), 295: 800-1. (Back calculation used in Great Britain.)

Montgomery, M. R.; Reason, M. J.; "Retrograde extrapolation of blood alcohol data: an applied approach," JOURNAL OF ANALYTICAL TOXICOLOGY (1992), 36 : 281-292. (This a author offers the rule of thumb. A person eliminates one drink per hour beginning from the first swallow of alcohol.)

Shajani, N.K.; Dinn, H. M.; "Blood alcohol concentrations reached in human subjects after consumption of alcoholic beverages in a social situation," CANADIAN SOCIETY OF FORENSIC SCIENCES JOURNAL (1985), 18 (1): 38-48. (Tries to replicate Dubowski's ALCOHOL TECHNICAL REPORTS study and fails to do so, their conclusions are that one can do back calculation or retrograde extrapolation.)

Stowell, A. R.; Stowell, L. I.; "Estimation of blood alcohol concentration after social drinking," JOURNAL OF FORENSIC SCIENCES (1998), 43 (1): 14-21. (BACs measured about an hour after cessation of drinking were within or very close to the predicted range based on back extrapolation from the actual 3.5 hour BAC result. 24 males using Widmarks, TBW, and fed.)

*Sturtevant, R. P; Sturtevant, Frank M.; "Circadian variation in rates of ethanol metabolism"; In: K. E. Crow, R. D. Batt (Eds.); Human metabolism of alcohol, volume I: Pharmacokinetics, medicolegal aspects and general interest; CRC Press (1989), 214p. (23-39). (The authors make the point that time of day affects ethanol elimination and breath alcohol concentrations are not reliable enough to use for research purposes since they underestimate the BAC by 10-15% or more.)

Ting-Kai Li; "The Absorption, distribution, and metabolism of ethanol and its effects on nutrition and hepatic function," In: Tabakof, B.; Sutker, P. B.; Randall, C. L. (eds.) , Medical and Social Aspects of Alcohol Abuse, New York, NY: Plenum Press, 1983, 403p. (47-77). (Widmark and Michaelis-Menten models are discussed with a variations among different groups.)

Watson, Patricia E.; Watson, Ian D.; Batt, Richard D.; "Prediction of blood alcohol concentrations in human subjects: updating the Widmark equation," JOURNAL OF STUDIES ON ALCOHOL (1981), 42 (7): 547-556.

Widmark, E. M. P.; 1932, Principles and Applications of Medicolegal Alcohol Determination, translated into English by R. C. Baselt, Department of Pathology, University of California, Davis, 1981, 163 p.

Williams, P. M.; "Analytical and physiological specificity issues in breath alcohol analysis," ALCOHOL, DRUGS, AND TRAFFIC SAFETY, (Proceedings of the 13th International Conference on Alcohol, Drugs and Traffic Safety, ICADTSA-T95; http://www.raru.adelaide.edu.au/T95/paper/s5p1.html (Widmarks used in Wales and British Courts. "In most cases the defendant will claim they had consumed, prior to driving, alcohol only in such quantity as to give rise to a reading not more than half the legal limit, which creates an impossible gap to be accounted for by the alleged interferant." The driver's own account of pre-driving consumption which, as one British judge so aptly put it is "so often the subject of dubious testimony".)

Wilson, J. R.; Erwin, V. G.; "Rate of alcohol metabolism; do not "correct" the B 60 estimate for comparisons among ethic groups," JOURNAL OF STUDIES ON ALCOHOL (1983), 44 (6): 1093-1096. (Used Watson's TBW and Widmark's r and B 60 to compute alcohol clearance.)

updated 12/31/09