According to this, from Brown University:
Alcohol and Your Body:
http://www.brown.edu/Student_Servic...&_other_drugs/alcohol/alcohol_&_your_body.php
A 100 lb woman would come pretty darned close, at .050, to the legal limit of .080, after consuming one beer in one hour. (And that is given no variables like disease state, food, menstrual cycle (!), etc. Or, as they say , better than I: "Note: these charts give you good general guidelines, but there are many factors involved in a person's reaction to alcohol, including body composition, use of medication or other drugs, mood changes and metabolism.")
According to them,
"Peak BAC [blood alcohol content] could be as much as 3 times higher in someone with an empty stomach than in someone who has eaten a meal before drinking." So, if this is true, and I assume it is,
that same 100 lb woman who drank one beer in one hour but had an empty stomach could well have a BAC of .015, in reality, or somwhere between the two. So yes, I do consider that a gamble.
This could well apply to men, too, when other factors are considered.
Do I still think it's ok to have a beer on the train or in celebration after work. As I said before, yes, it's likely fine.
But I don't think it's EVER as cut and dry as some want to make it out to be, and I think that almost any drinking and driving can be a gamble. (And most people underestimate what they drink, and their judgement about it becomes impaired, too, at BAC levels lower than the legal limit.)