Table 2 Examples of different metrics and dose ranges used in studies for the assessment of the toxicity of e-cigarette (not exhaustive)

Number of puffs (puff volume)

10–60 puffs (55 mL)

20 puffs (166 mL)

0–35 puffs (70 mL)

0–400 puffs (55 mL)

0–900 puffs (55 mL)

[48]

[49]

[50, 51]

[16]

[52]

Puffs/mL*

0–0.5 puffs/mL

0.075–0.75 puffs/mL

0.02–6 puffs/mL

0–280 puffs/L

[53]

[54]

[5, 55]

[56]

Puffs/m²

85 and 257 puffs/m²

[57]

Concentration of a compound** (µM; mM; mg/mL)

10–1000 µM flavor

1–5 mM flavor

0–600 mg/mL heptyl butyrate, methyl stearate, butyl methacrylate and heptanal

0–10 mg/mL for diverse compounds including flavors

[37, 58]

[59]

[34]

[60]

Ratio (%), corresponding to the dilution of e-liquid

0.001–1%

0–0.3%

0–1%

0–3%

0–4%

0–10%

0–30%

[61, 62]

[63]

[60]

[50]

[64]

[55, 65]

[51]

Ratio (%), corresponding to the dilution of a cigarette or aerosol extract

0.625–20%

3.125–100%

12.5–100%

40–100%

[66]

[67, 68]

[69]

[70]