Is It Bad to Use the Same Plastic Water Bottle Every Day?

If you’re not washing it, then yeah, it can get kind of gross. Reusing an unwashed bottle or cup, even if you’re “only” drinking water out of it, puts your mouth in intimate contact with a wonderful bacterial breeding ground.

Bacteria grow really well in moist, warm environments. While almost any similar container will suffice, a narrow-mouthed plastic water bottle is difficult to scrub and especially friendly to bacterial growth. In a 2003 study, Canadian researchers collected samples from children’s water bottles and found that almost two-thirds contained bacterial contamination that exceeded safe drinking water guidelines. While the study couldn’t pinpoint the source of the contamination, the researchers thought that the bacteria most likely simply made the leap from the students’ hands to the bottles and set up shop.

So, you have to vanquish the bacteria between uses, but here’s the snag to washing your bottle: cleaning the things might actually make them unsafe in a different way. Bisphenol A or BPA is a chemical compound used in the making of polycarbonate plastics, including some kinds of plastic bottles. It mimics estrogen and binds to the same receptors in the human body as natural hormones. Over the years, it’s been linked to everything from cancer cell growth and decreased sperm count to developmental and neurological issues.

When you give a bottle a good scrub, you’re wearing down the plastic and allowing BPA and other chemicals to leach from it and into the bottle’s contents. Using the bottles for hot liquids, putting them in the dishwasher, and trying to sterilize them with boiling water all do the same thing. Dr. Scott Belcher, a pharmacolgist at the University of Cincinnati, has done several studies on BPA in bottles and found that heat is a big factor in its release. One study showed that when BPA-containing drinking bottles are exposed to boiling water, the chemical is released 15 to 55 times faster than normal. “These are fantastic products and they work well,” Belcher told Scientific American. “[But] based on my knowledge of the scientific data, there is reason for caution. I have made a decision for myself not to use them."

As for the alternative to polycarbonate plastics, PET, the jury is largely still out on how safe it is. The contents of the bottle and the temperature at which it’s stored and washed both seem to influence the amount of plastic components leaching from it and the rate at which they leach (Update: Just a few of the relevant studies on bottles from both the US and Europe can be found here, here, here and here.) At the very least, solar water disinfection appears safe (depending on where the bottle came from), if a little inconvenient.

So what's a person to do to avoid illness from both creepy crawlies and plastic components? Regularly-washed glass, stainless steel or aluminum water bottles seem to be the way to go. They’re dishwasher-safe and easier to clean, providing less favorable breeding grounds for germs. They’re also chemically safe, according to one of Belcher’s most recent studies.

Water bottles image via Shutterstock

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'Lime Disease' Could Give You a Nasty Rash This Summer
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A cold Corona or virgin margarita is best enjoyed by the pool, but watch where you’re squeezing those limes. As Slate illustrates in a new video, there’s a lesser-known “lime disease,” and it can give you a nasty skin rash if you’re not careful.

When lime juice comes into contact with your skin and is then exposed to UV rays, it can cause a chemical reaction that results in phytophotodermatitis. It looks a little like a poison ivy reaction or sun poisoning, and some of the symptoms include redness, blistering, and inflammation. It’s the same reaction caused by a corrosive sap on the giant hogweed, an invasive weed that’s spreading throughout the U.S.

"Lime disease" may sound random, but it’s a lot more common than you might think. Dermatologist Barry D. Goldman tells Slate he sees cases of the skin condition almost daily in the summer. Some people have even reported receiving second-degree burns as a result of the citric acid from lime juice. According to the Mayo Clinic, the chemical that causes phytophotodermatitis can also be found in wild parsnip, wild dill, wild parsley, buttercups, and other citrus fruits.

To play it safe, keep your limes confined to the great indoors or wash your hands with soap after handling the fruit. You can learn more about phytophotodermatitis by checking out Slate’s video below.

[h/t Slate]

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Why Eating From a Smaller Plate Might Not Be an Effective Dieting Trick 
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It might be time to rewrite the diet books. Israeli psychologists have cast doubt on the widespread belief that eating from smaller plates helps you control food portions and feel fuller, Scientific American reports.

Past studies have shown that this mind trick, called the Delboeuf illusion, influences the amount of food that people eat. In one 2012 study, participants who were given larger bowls ended up eating more soup overall than those given smaller bowls.

However, researchers from Ben-Gurion University in Negev, Israel, concluded in a study published in the journal Appetite that the effectiveness of the illusion depends on how empty your stomach is. The team of scientists studied two groups of participants: one that ate three hours before the experiment, and another that ate one hour prior. When participants were shown images of pizzas on serving trays of varying sizes, the group that hadn’t eaten in several hours was more accurate in assessing the size of pizzas. In other words, the hungrier they were, the less likely they were to be fooled by the different trays.

However, both groups were equally tricked by the illusion when they were asked to estimate the size of non-food objects, such as black circles inside of white circles and hubcaps within tires. Researchers say this demonstrates that motivational factors, like appetite, affects how we perceive food. The findings also dovetail with the results of an earlier study, which concluded that overweight people are less likely to fall for the illusion than people of a normal weight.

So go ahead and get a large plate every now and then. At the very least, it may save you a second trip to the buffet table.

[h/t Scientific American]

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