Application of Bayesian Theory to the reporting of results in alcohol hair testing.

Authors: Bossers, L.C.A.M. and Paul, R.

Journal: Forensic Science International.

Volume: 242

Pages: 56-58


Currently, alcohol hair analysis can be used to determine someone’s alcohol use over a period of time or show a history of someone’s alcohol usage [1]. This is achieved through the application of certain cut off values to the data. For the metabolite Ethyl glucuronide (EtG) a concentration of above 7 or 30 pg/mg represents “not abstinent” and “heavy alcohol consumption” respectively, of which the latter is defined as drinking more than 60 g per day [1]. We would like to propose an alternative interpretation system, one that utilises Bayesian theory to give more information to the scientist. This approach considers all concentration ranges for the alcohol metabolites which may be encountered and allows a mathematical reason to be presented as to why, for example, EtG concentrations of 27, 53 or 63 pg/mg may be able to indicate more information than is currently available with the cut-off based approach.

Source: Manual