I work/live on ships (freighters) for 6 months a year in what would be classified as the coastal (Great Lakes) trade. Alcohol is not allowed, period. Since the Exxon Valdez fucked it up for all us sailors, things have changed. Having said all of that, a zero tolerance scheme is detrimental to people. The job is not a good one and no matter what you do, there comes a day when you need to decompress. Office types may disagree, but until you've worked in an industrial environment, you will not know how it feels. And if you say you do and you don't need a drink after being yelled at for 4hrs in 35*C heat then you need your head checked.
I am an alcoholic, simply through the fact that I love the taste of beer. It's amazing, different variations on malts, hops, yeast, water. I route my vacations around City and breweries. I will not change and nor do I want to. If I die an early death through liver failure or whatever then so be it, I have loved what I do on my free time and I feel I have worked enough to warrant it.