TY - JOUR

T1 - Total body water is the preferred method to use in forensic blood-alcohol calculations rather than ethanol's volume of distribution

AU - Maskell, Peter D.

AU - Jones, A. Wayne

AU - Heymsfield, Steven B.

AU - Shapses, Sue

AU - Johnston, Atholl

N1 - Publisher Copyright:
© 2020 Elsevier B.V.

PY - 2020/11

Y1 - 2020/11

N2 - During the prosecution and defence of drink-driving cases, forensic practitioners are often required to engage in various blood-alcohol calculations, such as whether or not the statutory limit was exceeded (e.g. 80 mg/100 mL, 0.08 g/100 mL or 0.80 g/L). For this purpose, most forensic scientists utilize the Widmark equation, or some modification thereof, to calculate a person's blood alcohol concentration (BAC) based on information about the amount of ethanol consumed and the pattern of drinking. This equation comes in two main forms; one of which incorporates the apparent volume of distribution of ethanol (V) and the other a person's total body water (TBW). In this study, we utilised two independent data sets, one involving the determination of V for ethanol in 173 men and 63 women, and the other TBW determined for 582 men and 884 women. Those subjects included in the TBW group represented various racial groups (Caucasians, African Americans, Hispanics, Asians and Puerto Ricans), with body mass index (BMI) ranging from 17 to 80 kg/m2. Both versions of the Widmark equation were evaluated in relation to their accuracy and precision in predicting TBW and/or V using the two most common anthropometric equations; those of Watson et al. and Forrest. Both anthropometric equations exhibited good accuracy (<4.3%) for the prediction of both TBW and V. However, the root mean square error was lower TBW was used for prediction (9.09–12.84%) rather than V (11.72–15.08%). Overall, this study has demonstrated (a) that blood-alcohol calculations are more reliable using TBW rather than V (b) that both equations (Watson et al. and Forrest) are applicable to ethnic groups other than Caucasians and (c) the Forrest equation predicts TBW in men and women with BMI from 17 to 35 kg/m2 and that the Watson et al. equation works for those with more extreme BMI; females (17–80 kg/m2) and males (17–67 kg/m2).

AB - During the prosecution and defence of drink-driving cases, forensic practitioners are often required to engage in various blood-alcohol calculations, such as whether or not the statutory limit was exceeded (e.g. 80 mg/100 mL, 0.08 g/100 mL or 0.80 g/L). For this purpose, most forensic scientists utilize the Widmark equation, or some modification thereof, to calculate a person's blood alcohol concentration (BAC) based on information about the amount of ethanol consumed and the pattern of drinking. This equation comes in two main forms; one of which incorporates the apparent volume of distribution of ethanol (V) and the other a person's total body water (TBW). In this study, we utilised two independent data sets, one involving the determination of V for ethanol in 173 men and 63 women, and the other TBW determined for 582 men and 884 women. Those subjects included in the TBW group represented various racial groups (Caucasians, African Americans, Hispanics, Asians and Puerto Ricans), with body mass index (BMI) ranging from 17 to 80 kg/m2. Both versions of the Widmark equation were evaluated in relation to their accuracy and precision in predicting TBW and/or V using the two most common anthropometric equations; those of Watson et al. and Forrest. Both anthropometric equations exhibited good accuracy (<4.3%) for the prediction of both TBW and V. However, the root mean square error was lower TBW was used for prediction (9.09–12.84%) rather than V (11.72–15.08%). Overall, this study has demonstrated (a) that blood-alcohol calculations are more reliable using TBW rather than V (b) that both equations (Watson et al. and Forrest) are applicable to ethnic groups other than Caucasians and (c) the Forrest equation predicts TBW in men and women with BMI from 17 to 35 kg/m2 and that the Watson et al. equation works for those with more extreme BMI; females (17–80 kg/m2) and males (17–67 kg/m2).

KW - Analysis

KW - Blood-alcohol calculations

KW - Body-water

KW - Distribution volume

KW - Ethanol

KW - Forensic technical defences

KW - Pharmacokinetics

KW - Widmark equation

UR - http://www.scopus.com/inward/record.url?scp=85093093003&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85093093003&partnerID=8YFLogxK

U2 - 10.1016/j.forsciint.2020.110532

DO - 10.1016/j.forsciint.2020.110532

M3 - Article

C2 - 33099270

AN - SCOPUS:85093093003

VL - 316

JO - Forensic Science International

JF - Forensic Science International

SN - 0379-0738

M1 - 110532

ER -