45 and he/she is up walking around, then he/she is definitely an alcoholic but probably on the verge of death. Most people would be passed out
cold, but an alcoholic can function (not well but much better than a social drinker) with a much higher BAL -- .2 to .3 is common.
Like ibizan said, .045 is about one drink, depending on the size of the person. To be considered too impaired to drive in Florida the limit is .08. Above .