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

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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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iStock // Ekaterina Minaeva
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Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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May 23, 2017
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