1-Propanol can provide evidence relevant to microbial ethanol formation, but a laboratory correlation does not automatically reveal how much of an individual autopsy ethanol result was produced after death. Pigaiani and colleagues developed a promising 2024 model in an experimental putrefactive-blood system. The conditions and limitations of that model must travel with its equation.
A constructed substrate, not a series of reconstructed drinking histories
The investigators combined ethanol-negative whole human blood from expired blood bags with 300 mg mixtures of cadaveric gastrointestinal mucosa and liver. Samples were placed in unpreserved 6 mL tubes, with sterile paraffin oil used to create strictly anaerobic conditions. This simulated aspects of decomposition without reproducing an intact body’s circulation, anatomy or exposure history.
For the time-course and correlation phase, ten blood preparations containing early-putrefactive tissue fragments and glucose above 100 mg/dL were incubated at 20°C for nine days. Volatile compounds were measured daily. Ten preparations and repeated daily readings are not ten independently validated forensic case reconstructions.
What the regression showed
In this phase, newly formed ethanol ranged from 0.01 to 0.57 g/L, while 1-propanol ranged from 0.006 to 0.053 g/L. The reported relationship had R² = 0.91 and P < 0.0001. The fitted equation was:
Ethanol (g/L) = 9.512 × 1-propanol (g/L) + 0.0131.
The authors reported a mean percentage error of 18.4% against measured ethanol. That is the paper’s reported model-performance statistic, not a ±18.4% uncertainty interval guaranteed for a new case. The figure’s confidence curves concern the regression line; they should not be treated as individual-case prediction limits.
The analytical result is separate from the source inference
Ethanol and other volatiles were measured with headspace GC–FID. The method used two capillary columns and the mean of replicate results, tert-butanol as internal standard, and a 0.5 g/L ethanol quality-control standard every five samples. The paper identifies an ethanol quantification limit of 0.01 g/L. This is chromatographic measurement of the experimental samples, not merely a presumptive alcohol screen.
Accurately measuring both compounds does not independently validate the equation in a specimen with a different microbial population, glucose content, temperature history or pre-existing ethanol. Analytical quantitation and attribution of origin remain separate steps.
Why automatic subtraction is not supported
The starting blood was ethanol-negative. The authors identified experiments beginning above 0.0 g/L ethanol as future work. The study therefore did not establish that the same relationship remains reliable in a person who drank before death and subsequently underwent microbial ethanol formation.
Glucose did not exceed 120 mg/dL in the reported experiments. The proposed extension to higher glucose levels was an expectation, not direct validation across severe hyperglycemia. Expected production of other higher alcohols, including 1-butanol, did not occur, highlighting that the microbial environment did not capture every real-case pattern.
These limits preclude using the formula as a universal subtraction rule to calculate a “true antemortem BAC.” The model does not establish impairment, drinking time or cause of death. It supports further investigation of microbial contribution within the specific experimental framework.
How the study helps a case review
Record the specimen source, collection delay, preservation, storage, units and complete volatile profile before considering any model. Compare the experimental conditions with the case conditions and identify the evidence supporting transfer. For a different route to evidence about predeath ethanol, see hospital specimens used in death investigations.
Primary source
Pigaiani N, Musile G, Scott KS, Dye DW, Ausania F, Davis GG, Bortolotti F. Post-mortem formation of ethanol: Is 1-propanol a reliable marker? A proof-of-concept study using an in vitro putrefactive environment setup. Journal of Forensic Sciences. 2024;69:974–985. doi:10.1111/1556-4029.15479.
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