At those levels, women were more frequently accident-involved than men. Laboratory studies of the responses by men and women to alcohol, however, provide inconclusive results. As Sutker et al. Since the body fat and total body water of men and women differ greatly even when they are the same age, height and weight, women reach a higher BAC than men for the same alcohol amount. Many early studies failed to take this into account, but more recent studies have used comparable BACs rather than equivalent doses.
More reliable evidence exists for an interaction between alcohol and drinking practices.
The Grand Rapids study reported that the likelihood of involvement in a collision for drivers at the same BAC was greatest for the drivers with the lowest daily alcohol consumption. They reported that heavy drinkers were less impaired than moderate drinkers at equal BACs on several psychomotor tasks. It also examined whether variations in drivers' age, gender, or drinking practices interacted with BAC and resulted in variability in the impairment produced by alcohol. One hundred sixty- eight subjects were classified by four age groups, two genders, and three drinking practice categories. Also, although evidence of an interaction of gender and alcohol is less substantial than the evidence of interactions of age and drinking practices and alcohol, the study included equal numbers of men and women in order to examine the issue.