How much can you drink for it to be safe to drive home?

Ever curious what your blood alcohol content is before driving home from that bar? Then read this story!

Courtesy James Palinsad /FlickR Creative Commons

Courtesy James Palinsad /FlickR Creative Commons

I know you’ve thought it. You’re at the bar. You’ve downed a couple beers. And now you’re wondering whether it’s safe to drive home. It’s better to be safe than sorry and to always designate a driver, but that doesn’t stop us from wondering whether we are actually safe to drive and what our blood alcohol content (BAC) actually is. Every state in the US has adopted the .08 rule for BAC level, but how much is that exactly?

Well, it’s hard to say and unfortunately I can’t give you clear numbers. In theory, if you binge (i.e. 5 drinks in 2 hours for men and 4 drinks in 2 hours for females) you will reach that level. But there are so many factors that aren’t accounted for in that. What if you’re a big guy or you just ate a big meal? Those things will definitely affect where your BAC level ends up. Bigger people will absorb alcohol slower and if you eat a lot, the alcohol won’t get absorbed into the blood stream as quickly.

Regardless of your weight, height, and eating habits, there are various tools you can use to estimate it. A curious writer from the Los Angeles Times recently took one of these tools, the BACtrack, for a test drive. The writer designed her own pseudo-experiment and drank two glasses of wine within two hours. She even snacked on some crackers and cheese during that time. The result? She had a BAC level of .08, which is the legal limit of driving intoxicated. And that’s only after 2 drinks.

How accurate is this machine? Well, the CEO says that it is accurate for 250 tests. There aren’t any third party tests that I know of to confirm this number, but either way, I think it’s fair to say that this machine or any other machine gives you a ballpark estimate of your actual BAC. Some things that I know through research that can affect your BAC level are mouthwash, lotions, and perfumes, so it’s hard to say how much of that stuff is being picked up by the devices. Also, as the article states, make sure to wait 20 minutes or so after drinking to take your BAC – otherwise, you’ll get a very inaccurate reading.

At the end of the day though, it’s your call and your choice. This article is a reminder to us all to be very aware that you may overestimate your actual BAC level and that even after waking up the morning after a crazy night, you can still be above the legal limit. Our bodies metabolize alcohol at about .01 every hour, which means 8 hours if you were at the .08 level and double that if you were like one of the people who had a level of .16 in the posted link. Research is also beginning to show that we are better at guessing our BAC level as we are still drinking, but poorer at guessing it as we are sobering up, meaning that we sober up slower than we think. So be careful next time you go out and designate a driver. It’s not worth the risk.

Rubin Khoddam, Clinical Psychology PhD student at University of Southern California, founder of Psych Connection.

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Categories: Addiction Connection, Articles, Blogs by Rubin

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2 replies


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