One company, BACtrack, has just released a key chain alcohol test about the size of a lighter for $50.

BACtrack claims its newest product, the Vio, will be a "game changer" for people who want to drink more responsibly. Technology like this, which can help people find out if they're around or over 0.08 BAC, the limit for driving, might even help make a dent in drunk driving rates and the 10,000 related deaths every year, the company's president and CEO Keith Nothacker tells us.

"Previously there was a stigma with alcohol testing, and we've been fighting that stigma," says Nothacker, who started the company in 2001 as a college senior, and is now based in San Francisco. "We want people to talk about their BAC and not be embarrassed."

The BACtrack app that goes with the Vio takes a reading of your BAC after you blow into the device. But it also allows you to text your friends your BAC. "So someone can say, 'I am two drinks in, I'm not meeting you there, here's my BAC,' " Nothacker says.

Other companies have also begun marketing smartphone blood-alcohol tests to quantified self enthusiasts — any any drinker who wants to be better informed. For example, there's the Breathometer, a device that plugs into the audio jack of the smartphone and connects with an app. It's also about $50.

Nothacker might be right that more testing devices in the hands of consumers — rather than just law enforcement — could help bring down consumption of alcohol. But the reading you get will be, at best, a ballpark figure of your actual BAC.

None of the smartphone devices are as precise or accurate as what the police will use to test your BAC if they pull you over under suspicion of intoxication. According to Nothacker, those devices can compensate for more variables, such as altitude.

But one interesting feature of both the Vio and the Breathometer tells you how long it will take to reach 0.0 BAC from wherever you are over 0. "So if you're drinking late, you'll see that you won't sober up until the next day in a lot of cases," Nothacker says.

But these companies are clear in their marketing materials about one thing: Don't use this tool to decide whether you should "operate a motor vehicle or equipment." And it's never safe to drink any amount of alcohol and drive, partly because there's a huge variation in how alcohol impairs individuals, even at very low BAC.

So if these devices can't help you decide definitively if you're too drunk to drive, why would you use it?

One public health researcher, who's familiar with the technology, says he thinks these new tools could help people make better decisions.

"The key chain Breathalyzer allows people to find out how much they've had to drink objectively. And they can get a pretty good sense of whether it's a good idea to drive," Michael McDonell, an associate professor in the department of psychiatry and behavioral sciences at the University of Washington, tells The Salt. "In study after study, we see that just objectively tracking your use of [a substance] will reduce your use."

And while a super accurate blood-alcohol test is essential if you're using it to decide whether to send someone to jail, knowing your BAC is 0.041 versus 0.047 is less important for a personal tool, says McDonell.

"If the outcome is to help a person stop using or reduce their use of alcohol, accuracy is less important," he says. "And those expensive devices are never going to get out there to everybody."

McDonell is planning to use the Vio in a study of incentive-based alcohol addiction treatment. He'll give patients the device. They'll measure their BAC and then send it to him through the app. If they blow a 0, they get a reward of some kind.

"It should allow us to deliver alcohol treatment in people's home, without having them come into the clinic. And that's big because we know most people don't come in," he says. The clinic is often too far or too time-consuming or they fear the stigma of being there, he says.

Our anecdotal playtime with the Vio certainly made us more aware of the degree of our intoxication. Soon, we were able to more accurately guess our BAC, which the Vio asks you to do before every measurement.

We also became more aware of just how much the amount of food in your stomach influences the rate at which you absorb alcohol — the more food you eat, and the slower you drink while eating, the slower your BAC will rise. That rate, though, differs person to person. Check out the graphs from our yeast experiment: The variation between three people of about the same age and weight is pretty significant.

But these tools are far from perfect. It turns out that it's a bit awkward to operate both blood-alcohol testing device and a smartphone app in a noisy bar with drunk people around you. And if you're lending the tool to a friend who's never used it before, it can be hard to tell if he's blowing hard enough into the device — the likely cause of several faulty readings of 0.0 one of our friends got with the Vio.

The Vio is also a bit fussy. We got a lot of error messages. And the company recommends you use it at least once a month to keep it moist and in working order. The texting feature is also a bit clunky, and there's some mixed messages with the marketing of the device. If BACtrack is trying to discourage people from going overboard with alcohol, why encourage them to post pictures of their drunk selves on the Internet through the app?

And while BACtrack says to wait at least 20 minutes after eating, drinking or smoking before blowing into the device, that can be inconvenient if you're already intoxicated and need a quick reading. And Nothacker notes it can take up to an hour for alcohol to be absorbed, so your BAC could continue to rise for 40 minutes after a reading.

All in all, though, a key chain blood-alcohol reader is a handy tool to have around. And we can easily imagine a future where people sign their texts and emails with their BAC: "This email was composed at BAC .06."

Maybe we should even try that here at The Salt: Over and out, with a BAC of 0.0.

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Key Chain Blood-Alcohol Testing May Make Quantified Drinking Easy