The influence of habitual alcohol intake on breath-alcohol concentrations following prolonged drinking.

Fifty-one healthy men aged 20-35 years kept daily drinking diaries for 4 weeks prior to a 90-min drinking session of 1 ml of ethanol/kg body weight, taken as 4% alcohol by volume lager, at a constant rate, whilst fasting. This was followed by repeat breath-alcohol measurements for 90 min. Habitually light drinkers had significantly lower breath-alcohol levels than heavier drinkers up to 10 min post-drinking. Variation in breath-alcohol level was independent of habitual intake 15-90 min post-drinking. However, habitually light drinkers still had significantly lower blood-alcohol levels than heavy drinkers 30 min post-drinking. Group mean post-drinking breath-alcohol levels peaked at 20 min in light and moderate drinkers, at 10 min in heavy drinkers and at 5 min in very heavy drinkers. Wide individual variation in peak and rate of decline of breath-alcohol levels occurred independently of habitual intake and despite experimental control for factors influential on alcohol kinetics. Algorithms for alcohol intake and breath concentrations have limited application if drinking is prolonged. We suggest that preabsorptive metabolism and/or delayed absorption of alcohol may contribute to lower breath-alcohol levels in habitually light drinkers for 10 min following alcohol intake under the conditions of this study.