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Dirty Money: The Cash In Your Wallet Is a Magnet for Germs

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If an item is handled by the public, whether it's a library book, a subway pole, or an ATM, you can count on it being filthy. One of the worst offenders is something most people carry around wherever they go: money. As TIME reports, a new study confirms that paper money is a magnet for germs and other microorganisms.

For their paper, which appears in the journal PLOS One, researchers swabbed dozens of $1 bills collected from New York City banks over the course of 2013. The results showed microbes from numerous sources living within the fibers. Most came from the human body, like skin bacteria, oral bacteria, and even vaginal bacteria. But non-human DNA was also prevalent. In the summer, researchers were most likely to find traces from pets like dogs and horses, while microbes from indoor fungi were more common in the winter. Skin break out lately? The bacteria to blame for acne were the most common microorganisms detected.

That list alone is enough to make you feel squeamish when leafing through your wallet, but it doesn't end there. American paper currency is 75 percent cotton and 25 percent linen; this composition makes it a cozy environment for other microorganisms like viruses. According to SmartMoney, the flu can survive on paper money for more than 10 days under the right conditions. E. coli and salmonella have also been detected on paper bills.

While these facts make a good case for washing your hands after each transaction, there's no reason to make the full switch to plastic. The same properties that make money such a good home for bacteria also make it hard to spread those germs to people. When microbes settle into the woven material of a dollar, they tend to stay there, even when you take it out and pass it to someone else. And if some microbes do rub off on you, your skin does a great job of keeping them from getting inside your body where they can do real harm. But you should still remember to use hand sanitizer before eating that burger you just paid for.

Unfortunately, objects touched by strangers aren't the only germ-infested environments to be aware of. Here are some of the dirtiest surfaces lurking in your home.

[h/t TIME]

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Animals
Owning a Dog May Add Years to Your Life, Study Shows
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We've said that having a furry friend can reduce depression, promote better sleep, and encourage more exercise. Now, research has indicated that caring for a canine might actually extend your lifespan.

Previous studies have shown that dog owners have an innate sense of comfort and increased well-being. A new paper published in Scientific Reports and conducted by Uppsala University in Sweden looked at the health records of 3.4 million of the country's residents. These records typically include personal data like marital status and whether the individual owns a pet. Researchers got additional insight from a national dog registry providing ownership information. According to the study, those with a dog for a housemate were less likely to die from cardiovascular disease or any other cause during the study's 12-year duration.

The study included adults 40 to 80 years old, with a mean age of 57. Researchers found that dogs were a positive predictor in health, particularly among singles. Those who had one were 33 percent less likely to die early than those who did not. Authors didn't conclude the exact reason behind the correlation: It could be active people are more likely to own dogs, that dogs promoted more activity, or that psychological factors like lowered incidences of depression might bolster overall well-being. Either way, having a pooch in your life could mean living a longer one.

[h/t Bloomberg]

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Live Smarter
Not Sure About Your Tap Water? Here's How to Test for Contaminants
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In the wake of Flint, Michigan's water crisis, you may have begun to wonder: Is my tap water safe? How would I know? To put your mind at ease—or just to satisfy your scientific curiosity—you can find out exactly what's in your municipal water pretty easily, as Popular Science reports. Depending on where you live, it might even be free.

A new water quality test called Tap Score, launched on Kickstarter in June 2017, helps you test for the most common household water contaminants for $120 per kit. You just need to take a few samples, mail them to the lab, and you'll get the results back in 10 days, telling you about lead levels, copper and cadmium content, arsenic, and other common hazardous materials that can make their way into water via pipes or wells. If you're mostly worried about lead, you can get a $40 test that only tells you about the lead and copper content of your water.

In New York State, a free lead-testing program will send you a test kit on request that allows you to send off samples of your water to a state-certified lab for processing, no purchase required. A few weeks later, you'll get a letter with the results, telling you what kind of lead levels were found in your water. This option is great if you live in New York, but if your state doesn't offer free testing (or only offers it to specific locations, like schools), there are other budget-friendly ways to test, too.

While mailing samples of your water off to a certified lab is the most accurate way to test your water, you can do it entirely at home with inexpensive strip tests that will only set you back $10 to $15. These tests aren't as sensitive as lab versions, and they don't test for as many contaminants, but they can tell you roughly whether you should be concerned about high levels of toxic metals like lead. The strip tests will only give you positive or negative readings, though, whereas the EPA and other official agencies test for the concentration of contaminants (the parts-per-billion) to determine the safety of a water source. If you're truly concerned with what's in your water, you should probably stick to sending your samples off to a professional, since you'll get a more detailed report of the results from a lab than from a colored strip.

In the future, there will likely be an even quicker way to test for lead and other metals—one that hooks up to your smartphone. Gitanjali Rao, an 11-year-old from Colorado, won the 2017 Young Scientist Challenge by inventing Tethys, a faster lead-testing device than what's currently on the market. With Tethys, instead of waiting for a lab, you can get results instantly. It's not commercially available yet, though, so for now, we'll have to stick with mail-away options.

[h/t Popular Science]

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