Dear Science,

My roommate talked me into making infused "martinis" at home by squeezing fruit we had from the grocery store into vodka. (Hey, we're in a depression. We have no money for the bar.) Hours into the adventure, I realized we hadn't washed any of the fruit that went into our drinks. Nor had either of us washed our hands before squeezing the fruit. Think of all the samonella outbreaks that have hit recently! Are we going to end up ill?

Concerned Home Bar Patron

The health of your digestive tract is in the hands of the sterilizing power of alcohol. How good is ethanol at killing disease-causing bugs? The mouth is the unrivaled place on the human body for bacteria and viruses. If ethanol can kill off this collection of scum and villainy, whatever can be found on fruit and your hands should be easy work. There is a reason most mouthwashes are alcohol based: High concentrations of ethanol do a pretty damn good job of killing off the nasty bugs. Fifty to sixty percent ethanol can take out most bacteria. Viruses require a higher punch—80 to 90 percent ethanol.

All that alcohol isn't just bad for the bugs; it chews up the cells lining your mouth as well. Sadly, all that mouthwash we've been swilling seems to be causing quite a bit of oral cancer, and only about half of people who get oral cancer live five years after diagnosis—that's with aggressive treatment. Most of us shouldn't be using alcohol-containing mouthwash every night.

Well, what of lower concentrations of alcohol? Below 50 percent, most bugs take it in stride. Horrifying experiments can be done with elementary-school kids, dirty hands, and bacterial-growth plates when comparing crappy hand sanitizer (less than 50 percent alcohol) to the good stuff. The plates planted with unwashed hands show some colonies of bacteria. Those sanitized with greater-than-60-percent-alcohol-content gels are clean. Hands sanitized with the cheap stuff grow lawns of bacteria. Lawns! Ethanol, in low concentrations, can be a food source for some bugs rather than a cause of doom.

Vodka is typically 80 proof, a mere 40 percent alcohol—not enough to kill off disease-causing bacteria or viruses. (Lawns!) Your infused-vodka drinks were also probably infused with more than juice; here's hoping you aren't barfing as you read this. Still, Science doesn't recommend increasing the proof of your liquor next time. Regular consumption of 180 proof (90 percent alcohol) hooch is likely to cause barfing and illness through other mechanisms. Next time, try some soap and water beforehand, and all should be well.

Tipsily yours,

Science

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