Distribution of ethanol between saliva and blood in man

1. Forty-eight male subjects drank ethanol (0.72 g/kg) as neat whisky on a fasting stomach within 20 min and the ethanol concentrations in saliva and capillary blood were determined at 30--60 min intervals for the next 7 h. 2. The concentration of ethanol in saliva was generally slightly higher than in capillary blood, as expected from their relative water contents. The mean saliva/blood ethanol ratio between 60 and 360 min from the start of drinking was 1.082 (s.e.m. = 0.0059), (n = 336). Moreover, the saliva/blood ethanol ratio was remarkably constant throughout the absorption, distribution and elimination phases of ethanol metabolism. 3. The saliva (y) and blood ethanol (x) concentrations (mmol/l) were highly correlated (r = 0.976, standard error = 0.011, P less than 0.001). The regression equation was y = 0.109 + 1.071x. The saliva and blood ethanol concentrations reached zero nearly simultaneously, there being no appreciable time lag in the saliva. 4. The results indicate that saliva is a practical medium for ethanol determinations and that blood ethanol can be reliably estimated from analysis of a saliva specimen. Saliva ethanol analysis could well serve as supporting evidence in clinical and medico-legal diagnosis of ethanol intoxication.