PEth / BAC Simulator (browser)

Single-page HTML app that lets you simulate blood alcohol concentration curves and resulting phosphatidylethanol (PEth) formation/decay. Open index.html in a browser.

You can use the simulator here (not necessarily the latest version).

Creator: Marko Grönroos, magi@iki.fi, magi.fi, 2025.

Quick start

# open directly from disk
xdg-open index.html   # or open index.html with your browser

Adjust sex, weight, age, and add one or more drinking sessions (start/end + grams of ethanol). Click Run simulation to view BAC (‰) and PEth (ng/mL) curves.

PEth half-life (days) is configurable; defaults to 4.5 days.

Tests (Node-only)

Requires only Node (no extra packages). Run:

npm test

Model (simplified)

References

The references inform parameter ranges and physiology:

Alcohol absorption and elimination:

• Watson et al, 1981, Prediction of blood alcohol concentrations in human subjects. Updating the Widmark Equation.
• Maskell et al, 2018, Evidence based survey of the distribution volume of ethanol: Comparison of empirically determined values with anthropometric measures.
• A. Jones, 2010, Evidence-based survey of the elimination rates of ethanol from blood with applications in forensic casework

PEth formation:

• Schröck et al, 2018 Determination of the formation rate of phosphatidylethanol by phospholipase D (PLD) in blood and test of two selective PLD inhibitors (PubMed 30103144)
• Stöth et al, 2023 Increase of PEth after Single Consumption of Alcohol and Evaluation of a Volumetric DBS Filter Paper Device (PubMed 36790103) describe PEth kinetics and half-life variability.

This simulator uses lightweight heuristic choices for interactivity, not for clinical use.

Blood alcohol

• Widmark volume of distribution: r = 0.68 (male), 0.55 (female), multiplied by blood-water density 1.055 to convert to kg of water.
• Absorption: first-order from stomach with k_abs ≈ 2 / h on an empty stomach (t½ ~0.35 h), capped at ~80 g/h; meal selection scales both (e.g., heavy meal factor ~0.45, light snack ~0.8) to reflect slower gastric emptying and lower peak BAC from fed conditions.
• Elimination: zero-order 0.15‰ / h (≈0.015 g/dL/h). Age factor scales ±0.3% per year around 40 (bounded to 0.85–1.25x); grams/hour uses the same volume factor as BAC.
• Concentration in ‰: BAC = grams_in_body / (r * weight_kg * 1.055).

PEth synthesis/decay

• Formation proportional to BAC with linear scaling: configurable. The literatue shows that the formation rate is somewhat nonlinear to BAC, but we use a simple linear scaling model. The default is a heuristic chosen from literature at 1‰, so that it typically balances in concentrations above and below:

  • 0.01% BAC (0.1 ‰): 0.002 μmol/L/h → 0.002 × 704.6 ≈ 1.4 ng/mL/h.
  • 0.1% BAC (1 ‰): 0.016 μmol/L/h → 0.016 × 704.6 ≈ 11.3 ng/mL/h. (used for the default)
  • 0.2% BAC (2 ‰): 0.025 μmol/L/h → 0.025 × 704.6 ≈ 17.6 ng/mL/h.
  • 0.3% BAC (3 ‰): 0.029 μmol/L/h → 0.029 × 704.6 ≈ 20.4 ng/mL/h.

• Decay first-order with half-life t½ = 4.5 days (k = ln(2)/(4.5*24)).

• Output is displayed as µmol/L, assuming PEth 16:0/18:1 molecular weight ≈704.6 g/mol (µmol/L = ng/mL / 704.6).

Simulation loop

• Time step: 5 minutes; horizon = max(96 h, last_drink_end + 48 h from first drink).
• Input ethanol is evenly ingested across each session duration, then absorbed and eliminated each step.
• Outputs: BAC curve, PEth curve, peak BAC, hours above 0.5‰, peak PEth.

Caveats

• Not a clinical or forensic tool; parameters are deliberately conservative and simplified.
• Breath/urine conversion, liver disease, meds, and inter-individual kinetics are ignored.
• PEth formation varies widely by person and drinking pattern; use this only for qualitative exploration.

Files

• index.html – App markup and asset references.
• style.css – Styling for the simulator.
• main.js – UI wiring and simulation logic.

Feel free to tweak constants in the script section to better match specific datasets.