WIDMARKS AND/OR BACK CALCULATION/
RETROGRADE EXTRAPOLATION

See also: Alcohol Bibliography
See also: Alcohol Impairment
See also: Alcohol Impairment Charts
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. Also contains information on Estimated Blood Concentration (EBAC)
http://en.wikipedia.org/wiki/Blood_alcohol_concentration

Bibliography

"Alcohol toxicology for prosecutors: targeting hardcore impaired drivers", American Prosecutors Research Institute, c2003 http://www.ndaa.org/pdf/toxicology_final.pdf

al-Lanqawi, T. A.; Moreland, T. A.; Ogg, G. D.; Tregaskis, B.; McEwen, J.; Stevenson, I. H.; "Ethanol pharmacokinetics--reproducibility in volunteer subjects," BRITISH JOURNAL OF CLINICAL PHARMACOLOGY (1991), 32 : 656.

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.

Bostic, J. Nicholas, "Alcohol-Related Offenses: Retrograde Extrapolation After Wager", Search this author and title on books.google.com

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://www.craftbeer.com/attachments/0000/1170/Computing_a_BAC_Estimate.pdf 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 above mentioned extreme values is 0.3% in each case.

Dubowski, Kurt M., "Time-of-Test DUI Laws vs. BAC Extrapolation", Center for Studies of Law in Action Borkenstein Course, Indiana University, c2006. Address: http://www.docstoc.com/docs/91644095/Time-of-Test-DUI-Laws-vs---The Borkenstein-Course Course is no longer at this website.

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.)

Iffland, R.; Jones, A. W.; "Evaluating alleged drinking after driving--the hip-flask defense. Part 1. Double blood samples and urine-to-blood alcohol relationship. MEDICINE, SCIENCE, AND THE LAW (2002), 42 (3): 207-24. This two-part article examines the strengths and weaknesses of various ways of investigating claims of drinking alcohol after driving, commonly known as the hip-flask or glove-compartment defense. In many countries the onus of proof in hip-flask cases rests on the prosecution. With good cooperation from the police and timely sampling of bodily fluids, such as blood and urine for forensic analysis of ethanol, useful evidence cam be mustered to support or challenge the truthfulness of alleged drinking after driving. The person's blood-alcohol concentration (BAC) can be compared with values expected on the basis of amount of alcohol consumed after driving, according to theoretical Widmark calculations. The actual BAC measured is the adjusted for the additional amount of alcohol consumed in the after-drink. Double blood samples, that is, taking two specimens of venous blood about 30-60 minutes apart and looking at the magnitude and direction of change in BAC provides little or no more information than a single blood specimen. However, the relationship between alcohol in blood and urine is very useful in hip-flask cases whereby the concentration expected in the primary urine is compare with the concentration in the bladder urine voided. The concentration of alcohol determined in a second urine sample collected 30-60 min later gives ethanol concentrations in blood and urine as a function of time provides a robust and practical review, congener analysis is presented, which entails comparing the concentrations of n-propanol and occasionally other congeners in the alcohol beverage allegedly consumed after driving with the volatiles present in the suspect's blood and urine determined by headspace gas chromatography.

Iffland, R.; Jones, A. W.; "Evaluating alleged drinking after driving--the hip-flask defense. Part 2. Congener analysis:, MEDICINE, SCIENCE, AND THE LAW (2003), 43 (1): 39-68. The second part of this review describes the principles and practices of forensic congener analysis as an alternative way to evaluate claims of drinking alcohol after driving. Congener analysis was developed, perfected and practiced in Germany as a way to evaluate the hip-flask defenses. This kind of defense challenged arises frequently when the drunk driving suspect is not apprehended at the wheel and especially after hit-and-run incidents. Besides ethanol and water, alcoholic beverages contain trace amounts of many other low-molecular substances, known collectively as congeners, which impart the characteristic smell and taste to the drink. Importantly, the congener profile can be used to identify a particular kind of alcoholic beverage. Forensic congener analysis entails making a qualitative and quantitative analysis of ethanol, methanol, n-propanol and the isomers of butanol in blood and urine from the apprehended driver and comparing the results with the know congener profile of the alcoholic beverage allegedly consumed after driving. Interpreting the results of congener analysis requires knowledge about the absorption, distribution and elimination pattern of the congener alcohols, including their oxidation and conjugation reactions, and any metabolic interactions with ethanol. Complications arise if drinks are with widely different congener profiles are consumed or if the same beverage was ingested both before and after driving. Despite these limitations, congener analysis can furnish compelling evidence to challenge or support claims of drinking alcohol after driving.

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.; "Are changes in blood-ethanol concentration during storage analytically significant? Importance of method imprecision." (CLINICAL CHEMISTRY AND LABORATORY MEDICINE (2007), 45 (10): 1299-304. "BACKGROUND: Knowledge about the stability of drugs and metabolites in biological fluids is important information when the analytical results are evaluated and interpreted. This study examines changes in blood-ethanol concentration (BEC) during the storage of specimens for up to 12 months at 4 degrees C. METHODS: Venous blood samples were taken from drunk drivers in evacuated glass tubes containing sodium fluoride and potassium oxalate as chemical preservatives. The concentrations of ethanol in blood were determined in duplicate by headspace gas chromatography on arrival at the laboratory and again after storage in a refrigerator at 4 degrees C for up to 12 months. RESULTS; The relationship between the standard deviation (SD) of analysis of ethanol at concentration intervals of 0.2 mg/g (BEC) was defined by the linear regression equation SD=0.0023+0.0104 BEC (r=0.99). At a mean BEC of 1.64 mg/g, the SD was 0.019 mg/g which corresponds to a coefficient of variation of 1.1%. The mean decrease in BEC (+/-SD) between first and second analysis was 0.105+/-0.0686 mg/g (t=19.3, d.f.=158, p<0.001) and the loss of alcohol was positively correlated with the duration (days) of storage (r=0.44, p<0.001), although with large inter-tube variations. A correlation also existed (r=0.23, p<0.01) between the loss of ethanol and the starting BEC. When blood sample (n=49) were opened 17 times to remove aliquots for analysis over 6.5 months, the BEC decreased by 0.217+/-0..054 mg/g compared to a fall of 0.101+/-0.076 mg/g in tubes kept unopened. None of the blood samples showed a significant increase in BEC after storage. CONCLUSIONS: To be considered analytically significant, the BEC had to decrease by 0.013 (2.6%), 0.028 (1.9%) and 0.045 mg/g (1.8%), respectively at starting concentrations of 0.5, 1.5, and 2.5 mg/g.

Jones, A. W., "Biomarkers or recent drinking, retrograde extrapolation of blood-alcohol concentration and plasma-to-blood distribution ration in a case of driving under the influence of alcohol", JOURNAL OF FORENSIC AND LEGAL MEDICINE (2011), 18 (5): 213-6. "This case report describes the police investigation of a road-traffic accident involving a collision at night (01.00 am) between car and a truck in which a passenger in the car was killed. The driver of the truck was found responsible for the crash although a roadside breath-alcohol test was negative (<0.1 mg/L breath or 20 mL or 100 mL blood). Because of injuries sustained in the crash, the female drier of the cars was not breath-tested at the time but was transported to a local hospital for emergency treatment. After swabbing the skin with isoproponol an indwelling catheter was inserted at 01.40 am. A blood sample was taken at 02.10 am and the plasma portion contained 8 mmol/L ethanol according to analysis at the hospital clinical laboratory using a gas chromatographic method. Another blood toxicology laboratory, although the result was negative (<10 mg/100 m:) at the time of the crash. The scientific bias for converting a plasma-ethanol concentration into a blood-ethanol concentration and back extrapolation of the driver's blood-alcohol sample by swabbing the skin with isopropanol is discussed along with the use of alcohol biomaarkers (ethyl glucuronide and ethyl sulphate) as evident of recent drinking.

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

Jones, A. W., "Body mass index and blood-alcohol calculations", JOURNAL OF ANALYTICAL TOXICOLOGY (2007), 31 (3): 177-8. (Letter to the Editor) Two subjects, a male and female who has widely different body mass indexes. Jones' point is that obesity is a problem as alcohol is diffused in to the TBW (total body water) and not adipose tissue and bone. Age, gender, weight and height also need to be taken into consideration.

Jones, A. W., Wigmore, J. G., House, C. J., "The course of the blood-alcohol curve after consumption of large amounts of alcohol under realistic conditions", CANADIAN SOCIETY OF FORENSIC SCIENCE JOURNAL, September, 2006, 36 (3).

Jones, A. W., Neri, "Evaluation of blood-ethanol profiles afgter consumption of alcohol together with a large meal", CANADIAN SOCIETY OF FORENSIC SCIENCE JOURNAL, (1991).

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.; Jorfeldt, L.; Hjertbert, H.; Jonsson, K. A.; "Physiological variations in blood ethanol measurements during the post-absorptive state," JOURNAL OF THE FORENSIC SCIENCES SOCIETY (1990), 30 ( 5) : 273-83. (9 volunteers, moderate drinkers, .08 g/kg body weight ethanol in orange juice over 30 minutes. Specimens of arterial plasma and venous whole blood were take at 3-10 minute intervals during the post-peak phase of ethanol metabolism. Time-to-time variations were seen, it was concluded that the study did not support the existence of sporadic fluctuations in the blood alcohol concentrations (BAC) profile but does support the need for careful control of sampling methods.

Jones, A. W.; "Ultra-rapid rate of ethanol elimination from blood in drunken drivers with extremely high blood-alcohol concentrations", INTERNATIONAL JOURNAL OF LEGAL MEDICINE (2008), 122(2): 129-34. "The rate of alcohol elimination from blood was determined in drunken drivers by taking two blood samples about 1 h(our) apart. These cases were selected because the individuals concerned had reached an extremely high blood-alcohol concentration (BAC) when they were apprehended. This suggests a period of continuous heavy drinking leading to the development of metabolic tolerance. Use of double blood samples to calculate the elimination rate of alcohol from blood is valid provided that drunken drivers are in the post-absorptive phase of the BAC curve, the time between sampling is not too short, and that zero-order elimination kinetics operates. Evidence in support of this came from other drunken drivers in which three consecutive blood samples were obtained at hourly intervals. The mean BAC (N-21) was 4.05 g/l (range, 2.71-5.18 g/l), and the average rate of alcohol elimination from blood was 0.33 gl(-1) h(-1) with a range of 0.20-0.62 gl)-1) h(-1). The possibility of ultra-rapid rates of ethanol elimination from blood in drunken drivers having extremely high BAC deserves to be considered in forensic casework, e.g., when retrograde extrapolations and other blood-alcohol calculations are made. The mechanism accounting for more rapid metabolism is probably related to induction of the microsomal enzyme (CYP2E1) pathway for ethanol oxidation, as one consequence of continuous heavy drinking. However, the dose of alcohol and the duration of drinking necessary to boost the activity of CYP2E1 enzymes in humans have not been found." (N=7 subjects?)

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)".

Levine, B; Smialek, J. E.; "Status of alcohol absorption in drinking drivers killed in traffic accidents", JOURNAL OF FORENSIC SCIENCES (2000), 45 (1), 3-6. One issue which constantly confronts the forensic toxicologist in drinking driver cases is the relationship between the breath or blood alcohol concentration (AC) of the driver at the time of an event such as a traffic stop or an accident and the AC measured at a time subsequent to the event. In theory, the AC can be rising, on a plateau or declining at the time of the event. Several studies have indicated that the overwhelming majority o drinking drivers are on a plateau or are post-absorptive at the time of the event. In this study, driver fatality cases investigated by the Office of the Chief Medial Examiner, State of Maryland during a three-year period were reviewed. Included in this study were cases positive for alcohol in the blood at a cutoff of 0.01g/dL and death occurring within 15 min. of the accident. In fact, many of these deaths were instantaneous or near instantaneous based on the injuries documented by the medical examiner at autopsy. The blood and urine were analyzed for alcohol by head-space gas chromatography and urine AC to blood AC rations were calculated. A total of 129 cases were included in this study. Eleven of the 129 cases (8.5%) had urine to blood AC ratio less that 1.0. It is likely that these individuals were in the absorptive phase at the time that the accident occurred. Thirty-two cases had a urine to blood AC ration between 1.0 and 1.2 inclusive. In these cases, the subject could be view as in the plateau phase of the blood AC versus time curve. The remaining 86 cases had a urine to blood ratio greater than 1.2. This suggests that these individuals were in the post-absorptive state at the time of the accident. The information acquired from this study provided additional evidence to support the notion that the vast majority of individuals are not in the absorptive phase at the time of the traffic stop or an accident.

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

State Montgomery v. Miller, Court of Appeals of Arizona, Division 1, "Dubowski and Jones state that retrograde extrapolation is valid based on the time of test,. . ." http://caselaw.findlaw.com/az-court-of-appeals/1662235.html

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.)

Pavlic, M.; Grubwieser, P.;Libiseller, K.; Rabl, W.; "Elimination rates of breath alcohol", FORENSIC SCIENCE INTERNATIONAL, (2007), 171 (1):16-21. Legal driving limits are set coequally with 0.5g/L blood alcohol concentration (BAC) or 0.25 mg/L breath alcohol concentration (BrAC) in Austria as well as in other European countries. As mostly some time elapses between BrAC measurement and driving offense, a back calculation of hourly BrAC elimination rates can thereby help to avoid unnecessary variances. A study with 59 participants was performed under social conditions. BrAC was determined with the legally accredited Alcotest 7110 MK III A every 30 min. and concomitantly venous blood samples were drawn. Five hundred and four BrAC/BAC value pairs were evaluated. The overall mean peak BrAC was calculated with 0.456 mg/L (+/-0.119 mg/L standard deviation). The mean hourly BrAC elimination rate was overall determined with 0.082 per h (0.050-0.114, 95% range). Mean rate for females (0.087 mg/L h(-1)) and the according 95% limits were statistically significantly higher than of males (mean rate 0.078 mg/L h(-1), p<0.04). Our results confirm the possibility to implement hourly BrAc elimination rates, provided that adequate statistical ranges and basic forensic scientific rules ht have been set up for alcohol back calculations are observed.

Relevant Studies & Scientific Principles That Support Retrogrades. Type this title into Google.com for a list of articles.

RETROGRADE EXTRAPOLATION OF BLOOD ALCOHOL: CONCENTRATION SURVIVES DAUBERT CHALLENGE http://www.wisconsinappeals.net/on-point-by-the-wisconsin-state-public-defender/retrograde-extrapolation-of-blood-alcohol-concentration-survives-daubert-challenge/

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.

Winek, C. L.; Wahba, W. W.; Dowell, J. L.; "Determination of absorption time of ethanol in social drinkers," FORENSIC SCIENCES INTERNATIONAL (1996), 77: 169-77. (Breath ethanol testing in a social setting.)

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.)

Zernig, G.; Battista, H. J.; "Basic pharmacokinetics of alcohol", IN: Zernig, G.; Saria, A.; Kurz, M; O'Malley, S. S., eds. HANDBOOK OF ALCOHOLISM. Boca Raton: CRC Press Inc., 2000, pp. 421-423. (11 ref.) This chapter outlines the absorption of alcohol and the rate and factors which influence rate, maximum blood levels achieved calculated by Widmark's formula, the process of metabolism.

Check out Retrograd Extrapolation on YouTube the expert witness discusses Kurt Dubowski and A, W. Jones. YouTube search retograde extrapolation toxicologist

 

updated 01/17/17