A chemistry professor at Houston-area Lonestar College allegedly taught students the wrong material for the majority of a semester, according to a local news station's investigative report.

Lonestar student Lauren Firmin told KHOU that she enrolled in and believed she was taking an "Intro to Chemistry" course in Fall 2013. However, the self-identified straight-A student realized something was wrong when she failed every test in the class, she said.

"I was getting 40's on every test. I studied as hard as I could, did everything in my power to try," Firmin told KHOU.

According to Firmin, Lonestar chemistry teacher Thao Shirley Nguyen admitted to the entire class that she had accidentally been teaching a more advanced general chemistry curriculum. "In short, Firmin says Nguyen told the class that she had NOT been teaching them the introductory course in chemistry that they originally signed up for, but an advanced course in chemistry," KHOU reports.

The situation was allegedly remedied by raising every student's grade. Firmin — who would otherwise have failed the course — recieved a B, she said.

While Nguyen refused comment on the claims and the Lonestar administration denied that the professor had taught the wrong course, the head of the university's science department confirmed the mistake in an email. Lonestar told KHOU that they would not be conducting a formal investigation.

[H/T Inside Higher Ed]

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Literally everything around us is made up of chemicals. That includes all foods. And the different kinds of chemicals they contain give the stuff we eat their flavors, colors, and smells.

On the blog Compound Interest, a chemist and teacher in the United Kingdom has illustrated the chemistry behind everyday foods through a series of colorful infographics. Check them all out below.

The taste of coffee partly comes from chlorogenic acids, which make up 8% of unroasted coffee beans.

Aldehydes found in the leaves of coriander (also known as cilantro) that are similar to those found in soaps and lotions are what cause the herb to taste soapy to some people.

A compound called myristicin could be one of several compounds responsible for nutmeg's hallucinogenic effect, produced when the spice is consumed in amounts larger than one tablespoon.

Theobromine, a stimulant that produces a similar effect to caffeine, is what makes chocolate toxic to dogs.

Beetroot gets its deep red color from a class of compounds called betacyanins. When betacyanins aren't broken down by the digestive system, they can also turn our pee red.

The breakdown of asparagusic acid, a chemical found only asparagus, might be what causes some people's pee to smell after eating the vegetable.

An enzyme that's released when an onion is chopped breaks down compounds within the onion to form the compound that irritates the eyes and causes them to water. 

Citric acid makes up around 6% of the lemon's juice and is what makes it taste sour.

A class of chemical compounds called furanocoumarins can interfere with how some prescription drugs are broken down by the body.

A family of compounds called capsaicinoids are what gives chillies their heat. A burning sensation is produced when the capsaicinoids bind to a receptor in the mouth.

Polyphenols give tea their taste and color.

Head over to the Compound Interest to see more educational graphics about chemical compounds »

SEE ALSO: What It Would Look Like If Your Banana Came With An Ingredient List

DON'T MISS: The Surprising Truth About How Many Chemicals Are In Everything We Eat

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When it comes to discovering elements, the U.K. is at the top of the table.

This periodic-table graphic was posted by Google Science Fair on Sunday, and it shows which nations discovered each element.

Leading the charge, the U.K. has discovered 24 elements, closely followed by the U.S. with 21, Sweden with 20, and Germany with 19.

A number of old favorites — including gold, mercury, and copper — are listed as “ancient discovery” and don’t have a country of origin.

NOW WATCH: 9 Animated Maps That Will Change The Way You See The World

MORE: 6 Scientifically Proven Things Men Can Do To Be More Attractive

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Most of us know how annoying chopping a raw onion can be because it usually makes our eyes sting and tear up.

But why does this happen?

A chemist teacher in the United Kingdom created a whole bunch of interesting graphics on his blog Compound Interest that explain the chemistry behind everyday foods.

One of the graphics, posted below, explains why slicing into an onion makes us cry. In short, an enzyme that's released when the onion is chopped breaks down compounds within the onion to form the compound that irritates the eyes and causes them to water. Read more about the specific compound produced in this process below.

Head over to the Compound Interest to see more educational graphics about chemical compounds »

SEE ALSO: What It Would Look Like If Your Banana Came With An Ingredient List

DON'T MISS: The Surprising Truth About How Many Chemicals Are In Everything We Eat

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Coca-Cola is removing the controversial ingredient Brominated Vegetable Oil (BVO) from Powerade, Consumerist reports.

But if you are getting ready to cheer and gleefully guzzle down some Powerade, you might want to reconsider: Removing BVO from sweetened beverages, as PepsiCo did with Gatorade last year, does not make them healthy.

In fact, most soft drinks are already pretty bad for you, BVO or not.

What is BVO?

If beverage manufacturers added fruit and citrus flavoring to carbonated water without a stabilizer like BVO, the flavor would separate from the water and float to the top. (Imagine trying to keep oil and water evenly mixed.) This would look gross and probably taste unpleasant too.

Adding BVO to flavorings lets food scientists change their density, so that they evenly mix with the rest of the drink and ensure you get that lemony flavor in every sip. (Yum, chemistry!)

BVO is found in Mountain Dew, Fresca, Fanta Orange, and a number of other citrus-y drinks. (Update: Coca-Cola said it would remove BVO from Fresca and Fanta by the end of the year.)

It caused a ruckus last year when a teenager's Change.org petition asking Gatorade to remove it garnered more than 200,000 signatures.

She pointed out that it was also used as a flame retardant ("Its use as a flame retardant does not preclude its use as a food ingredient so long as the food use is safe," an FDA spokesperson said). The EPA is currently investigating the health risks of brominated flame retardants, but we'll stick to a discussion of the use of BVO as a food additive.

Is BVO safe?

For decades, the FDA has allowed BVO as a food additive on an "interim" basis, meaning they believe it is safe, although additional studies could conceivably find that it should be banned (as it is in the European Union). The concentration of BVO in a beverage cannot legally exceed 15 parts per million (that's 0.0015%).

There is some concern that BVO builds up in the body, reaching levels that could be dangerous. But early FDA studies actually tested BVO in animals at levels as high 3,600 parts per million and found no effects.

While there's plenty of reasons to double check the safety of chemicals in our foods, an ingredient like BVO added in tiny amounts is not the real problem with your soda addiction, and focusing on these compounds takes away the heat from the real problem: the added sugar.

Newsflash: Soda is not healthy

Stories of people who have been poisoned by BVO miss the main facts: These people were drinking soda in mind-blowing amounts.

You may have heard about the man who developed a rare case of brominism (a kind of poisoning) after drinking too much fruity soda. The story is true — but there's an important caveat: He was drinking two to four liters of the soda every day.

Another patient, a 63-year-old man, developed ulcers on his hands after drinking 8 liters of Ruby Red Squirt — daily, for several months.

That means that while both men were consuming more BVO than was safe, they were also ingesting a minimum of 250 grams of sugar — more than 20 times the amount recommended by the World Health Organization's updated guidelines.

"Any normal level of consumption of BVO would not cause any health problems — except the risk of diabetes and obesity from drinking that much sugar water," Zane Horowitz, medical director of the Oregon Poison Center, told Environmental Health News.

What should you do?

Powerade, Gatorade, and other sports drinks don't have nearly as much sugar as, say, Mountain Dew, but they still have around 20 grams per serving — or up to 50 grams if you thirstily consume a whole bottle after a run. While brominated vegetable oil comes near the very end of Powerade's ingredient list, high-fructose corn syrup is number two.

"While any harms of BVO are speculative, the public health toll of excess calories and sugar is well-established,"notes Dr. David Katz, the director of the Yale Prevention Research Center. "I don't drink any of the products that contain BVO — and wouldn't drink them if they didn't, either."

You may want to follow Katz's advice: If you're concerned about your health enough to petition a soda company about BVO, you'd be better off just avoiding soda and sugar-sweetened beverages all together.

SUGAR IS THE REAL PROBLEM: Here Are 15 Terrible Things That Happen If You Eat Too Much Of It

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Machines that can fix themselves are such staples in fantastic fiction that the concept has its own name at TV Tropes (the 'net's ultimate guide to fiction cliches): Self Healing Phlebotinum.

In reality, chemists and engineers have devised materials and coatings that "self-heal” minute holes or thin cracks, often by melting and reforming under some sort of applied heat. But the size of the gap that can be repaired has been extremely limited.

Until now: A new plastic described last week in the journal Science contains a self-healing system that can repair sizable holes of greater than 3 centimeters (1.18 inches) in diameter, and recreate much of the plastic's original strength at the same time.

This new self-healing technique is both chemical and mechanical. The researchers were inspired by the human circulatory system to create a plastic, or polymer, laced with extremely narrow "veins," then filled them with one of two different liquids, or monomers.

When the plastic ruptures and cracks, the veins break open and the liquids mix, setting off two sequential chemical reactions: First the mixture turns into a gel. Then, it hardens up.

As long as the liquids continue to pump out of their channels and mix together, the plastic continues to grow, effectively "scarring over" and sealing off the hole or gap.

Sentient space ship fans take note: We're not quite in TARDIS territory yet. This new plastic has been tested only in the laboratory. If it can be made to work in real-world conditions, however, it's likely to have diverse applications in both inner and outer space.

This article originally appeared on Popular Science

SEE ALSO: 6 Futuristic Construction Materials That Will Change The Way We Build Stuff

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Humans love caffeine. 

It's the world's most popular psychoactive drug, with a full 90% of Americans consuming it on a daily basis, be it through coffee, tea, or soda.

As anyone who feels like a slug before their morning cup knows, caffeine has loads of effects on productivity, like: 

• Drinking coffee after first learning something increases the chance you'll remember it.
• Consuming caffeine makes people more sociable.
• Drinking coffee improves alertness. 

The video at the bottom of the post from the American Chemical Society does a great job of illustrating the chemistry underlying these effects.

It goes like this. 

1. Caffeine comes into your body whole.

2. Then the caffeine molecule enters your liver, where enzymes cut off three methyl groups to form three more small molecules. 

3. The molecules in question are theobromine, paraxanthine, and theophylline. 

4. Together with the original caffeine molecule, they heighten your brain activity, get nutrients flowing, increase your athleticism, and boost your focus. 

 Watch the full video to get the full lowdown on the chemistry of caffeinated productivity. 

Kudos to Lifehacker, where we first spotted the video. 

SEE ALSO: Never Hold A Hot Cup Of Coffee When You're Negotiating

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Everyone’s familiar with the smell of old books, the weirdly intoxicating scent that haunts libraries and second-hand book stores. Similarly, who doesn’t enjoy riffling through the pages of a newly purchased book and breathing in the crisp aroma of new paper and freshly printed ink? As with all aromas, the origins can be traced back to a number of chemical constituents, so we can examine the processes and compounds that can contribute to both.

As far as the smell of new books goes, it’s actually quite difficult to pinpoint specific compounds, for a number of reasons. Firstly, there seems to be a scarcity of scientific research that’s been carried out on the subject – to be fair, it’s understandable why it might not exactly be high up on the priority list. Secondly, the variation in the chemicals used to manufacture books also means that it’s an aroma that will vary from book to book. Add to this the fact that there are literally hundreds of compounds involved, and it becomes clearer why it evades attribution to a small selection of chemicals.

It’s likely that the bulk of ‘new book smell’ can be put down to three main sources: the paper itself (and the chemicals used in its manufacture), the inks used to print the book, and the adhesives used in the book-binding process.

The manufacture of paper requires the use of chemicals at several stages. Large amounts of paper are made from wood pulp (though it can also be made from cotton and textiles) – chemicals such as sodium hydroxide, often referred to in this context as ‘caustic soda’, can be added to increase pH and cause fibres in the pulp to swell. The fibres are then bleached with a number of other chemicals, including hydrogen peroxide; then, they are mixed with large amounts of water. This water will contain additives to modify the properties of the the paper – for example, AKD (alkyl ketene dimer) is commonly used as a ‘sizing agent’ to improve the water-resistance of the paper.

Many other chemicals are also used – this is just a very rough overview. The upshot of this is that some of these chemicals can contribute, through their reactions or otherwise, to the release of volatile organic compounds (VOCs) into the air, the odours of which we can detect. The same is true of chemicals used in the inks, and the adhesives used in the books. A number of different adhesives are used for book-binding, many of which are based on organic ‘co-polymers’ – large numbers of smaller molecules chemically chained together.

As stated, differences in paper, adhesives, and inks used will influence the ‘new book smell’, so not all new books will smell the same – perhaps the reason why no research has yet attempted to definitively define the aroma.

An aroma that has had much more research carried out around it, however, is that of old books. There’s a reason for this, as it’s been investigated as a potential method for assessing the condition of old books, by monitoring the concentrations of different organic compounds that they give off. As a result, we can be a little more certain on some of the many compounds that contribute to the smell.

Generally, it is the chemical breakdown of compounds within paper that leads to the production of ‘old book smell’. Paper contains, amongst other chemicals, cellulose, and smaller amounts of lignin. Both of these originate from the trees the paper is made from; finer papers will contain less lignin than, for example, newsprint. In trees, lignin helps bind cellulose fibres together, keeping the wood stiff; it’s also responsible for paper yellowing with age, as oxidation reactions cause it to break down into acids, which then help break down cellulose.

‘Old book smell’ is derived from this chemical degradation. Modern, high quality papers will undergo chemical processing to remove lignin, but breakdown of cellulose in the paper can still occur (albeit at a much slower rate) due to the presence of acids in the surroundings. These reactions, referred to generally as ‘acid hydrolysis’, produce a wide range of volatile organic compounds, many of which are likely to contribute to the smell of old books. A selected number of compounds have had their contributions pinpointed: benzaldehyde adds an almond-like scent; vanillin adds a vanilla-like scent; ethyl benzene and toluene impart sweet odours; and 2-ethyl hexanol has a ‘slightly floral’ contribution. Other aldehydes and alcohols produced by these reactions have low odour thresholds and also contribute.

Other compounds given off have been marked as useful for determining the extent of degradation of old books. Furfural is one of these compounds, shown below. It can also be used to determine the age and composition of books, with books published after the mid-1800s emitting more furfural, and its emission generally increasing with publication year relative to older books composed of cotton or linen paper.

So, in conclusion, as with many aromas, we can’t point to one specific compound, or family of compounds, and categorically state that it’s the cause of the scent. However, we can identify potential contributors, and, particular in the case of old book smell, a number of compounds have been suggested. If anyone’s able to provide further information on ‘new book smell’ and its origins, it would be great to include some more specific details, but I suspect the large variations in the book-making process make this a tough ask.

In the meantime, if you can’t get enough of that new book or old book smell, you might be interested to learn that one company has produced a range of aerosols designed to replicate them, although they no longer seem to be available to purchase. Alternatively, if you yourself would rather smell like a book, it seems the aroma is also available in perfume form.

SEE ALSO: 25 Popular Business Books Summarized In One Sentence Each

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Alexander "Sasha" Shulgin, the inventor of more than 200 psychedelic compounds, died yesterday at 88.

While Shulgin is best known for his work with the popular party drug Ecstasy (or MDMA), the anti-establishment scientist's past is full of surprises: He began studying mind-altering drugs with the backing of the giant multinational company Dow Chemical and was later granted a research license from the U.S. Drug Enforcement Agency (DEA).

From Pesticides To Psychedelics

Shulgin, who claimed to have had more than 4,000 psychedelic experiences, entered Harvard University at age 16 on a scholarship to study organic chemistry. He left two years later to join the Navy. After serving in WWII, Shulgin went on to earn his bachelor's degree and doctorate in biochemistry from the University of California, Berkeley.

In the late 1950s, Shulgin began working as a senior research chemist at Dow Chemical, where he helped to develop the first biodegradable pesticide, Zectran. After the pesticide's tremendous success, Shulgin was "given freedom to pursue research of his own design" at the company, according to the Alexander Shulgin Research Institute.

Around the same time, Shulgin had his first psychedelic experience with mescaline, the active ingredient in the small, naturally-occuring cactus peyote. He began to study the plant's chemical makeup. While employed at Dow, Shulgin published more than six papers on the psychedelic properties of substances like nutmeg oil and mescaline in respected journals like Nature and Mind.

"But while America's anti-drug fervor picked up, Dow found itself in the uncomfortable position of holding several patents on psychedelic drugs," reported the Los Angeles Times.

In 1965, Shulgin left Dow and opened his own personal laboratory behind his house in Lafayette, California, where he developed and tested new psychedelic compounds with a small group of friends and his wife, Ann.

Friends In The Drug Enforcement Agency

For almost 40 years, Shulgin continued to experiment and work out of his home laboratory. And for 20 of those years, he held a Drug Enforcement Agency (DEA) Schedule I research license. (The license lets a select group of scientists legally experiment with controlled substances whose possession would otherwise be considered illegal.)

According to the DEA website, "Schedule I drugs, substances, or chemicals are defined as drugs with no currently accepted medical use and a high potential for abuse. Schedule I drugs are the most dangerous drugs of all the drug schedules with potentially severe psychological or physical dependence."

Shulgin maintained a close relationship with the very government agency tasked with overseeing his research, according to a 2005 profile in The New York Times Magazine:

The head of the D.E.A.'s Western Laboratory, Bob Sager, was one of [Shulgin's] closest friends. Sager officiated at the Shulgins' wedding and, a year later, was married on Shulgin's lawn. Through Sager, the agency came to rely on Shulgin: he would give pharmacology talks to the agents, make drug samples for the forensic teams and serve as an expert witness — though, he is quick to point out, he appeared much more frequently for the defense.

He was also the author of a definitive textbook used by the DEA called "Controlled Substances: Chemical & Legal Guide to Federal Drug Laws" (Ronin Publishing, 1988).

Shulgin never considered his experimentation with psychedelics, many of which were eventually labeled as Schedule I, to be illegal. Most of his research involved trying to create new drugs that hadn't been classified. "It's my stance that what I do is nothing illegal," he said in a 1995 interview with the Los Angeles Times.

But in 1993, the DEA raided Shulgin's lab. There has been speculation that the raid was prompted by the publication two years earlier of PiHKAL: A Chemical Love Story, which stands for "Phenethylamines I Have Known and Loved" with his wife Ann. The book includes instructions on how to synthesize chemical compounds and the appropriate doses. After the raid, Shulgin was fined $25,000 for violating the terms of his Schedule I license and his license was terminated.

The MDMA Renaissance

It was in 1976 that Shulgin first began experimenting with MDMA, the substance that eventually earned the nickname the 'Godfather of Ecstasy.'

The drug was originally "designed by the pharmaceutical company Merck in 1912 to produce a blood-clotting agent," according to The Guardian. Shulgin resynthesized MDMA after reading a report from a graduate student that hinted at the drug's potential.

While MDMA is known to cause changes in perception and an enhanced sense of touch, Shulgin wasn't profoundly impacted by the drug and referred to it as a "low-calorie martini," likening the experience to an alcohol buzz in an interview with The New York Times.

Throughout his research career, Shulgin was particularly careful of drug dosages. He would begin to test chemical compounds by ingesting incredibly small amounts that wouldn't cause any side effects and slowly build up the dosage.

He was also a strong advocate for the therapeutic qualities of MDMA, but his research on MDMA was halted once his Schedule I license was terminated.

Today, MDMA is the subject of a series of clinical trials, including as a potential therapy for military veterans suffering from post-traumatic stress disorder.

SEE ALSO: VETERAN: Ecstasy Drug Saved Me From My Battle With PTSD

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Christopher H. Hendon, a PhD student in theoretical and computational chemistry at the University of Bath, was sitting in his local coffee shop when he overheard a conversation between two frustrated baristas. 

"They were having problems with coffee that tasted good one day and not another," he explained to Business Insider. While that's a frustrating mystery for a coffee shop with exacting standards, "from a chemistry point of view, that's an interesting problem."

Specialty coffee shops can control where their beans come from and how they are roasted, ground, and brewed, but there's one crucial factor that can throw a wrench into the whole operation, Hendon found: the water.

To truly brew a perfect cup, it's not enough to know what kind of beans you're working with. You also have to know about the chemistry of the water.

What's In The Water?

Most people know that water can be "hard" (full of minerals like magnesium) or "soft" (most distilled water falls into this category). But there's also natural variation. Here's a map of the U.S. that shows how water hardness varies from place to place, although it can also vary over time:

When Hendon teamed up with baristas Lesley Colonna-Dashwood and Maxwell Colonna-Dashwood — who won the UK Barista Championship in April — they found that different kinds of "hardness" in water bring out significantly different flavors in coffee. (Hendon ran the experiments using a computer, while the coffee shop owners actually brewed sample cups.)

So why does the water matter?

Roasted coffee beans are packed with compounds like citric acid, lactic acid, and eugenol (a compound that adds a "woodsy" taste). All of those compounds occur in varying levels in beans, giving coffee its complex and highly varied flavors.

Water, meanwhile, has a complexity all its own. When you turn on a tap, you're not just getting H2O, but different levels of ions like magnesium and calcium. (Higher levels = "harder.")

Here's the key: Some of the compounds in hard water are "sticky," glomming onto certain compounds in coffee when they meet (in your coffeemaker). The more eugenol the water hangs on to, for example, the woodsier the taste of your coffee will be. 

Magnesium is particularly sticky, meaning water that's high in magnesium will make coffee with a stronger flavor (and higher levels of caffeine). Hard water can also have high levels of bicarbonate, though, which Hendon found could lead to more bitter flavors coming through.

But while hard water is a bit of a gamble, depending on which minerals are in the higest concentrations, soft water had no benefits at all. Its chemical composition "results in very bad extraction power," Hendon explained.

Soft water often contains sodium, but that has no flavor stickiness (for good or bad flavors), Hendon found. That means that if you use the exact same beans, you'll get a much stronger flavor if you use high-magnesium "hard water" in place of distilled or softened water.

A Chemically Perfect Cup

Unlike Hendon, the average coffee lover is not also a chemist. You can't easily alter the composition of your water supply every time you want a delicious cup of coffee. 

But there's good news: You don't have to. Understanding that the kind of water you use can change the kind of coffee you get will help you on the path to the perfect brew — even if you're stuck with whatever comes out of your kitchen tap.

To start, you can look up the hardness of your water online (New Yorkers can call 311), and then buy beans that are meant for "soft" or "hard" water. (Hendon said that's the kind of thing upscale roasters will know.) 

Sure, you won't know the specific water compounds that will pair perfectly with a particular roast — that's the kind of rigorous coffee science Hendon and Colonna-Dashwood will be leaning on at the World Barista Championship next week — but you'll already be a step ahead if you buy from a local roaster.

When roasters test their beans, they do so using local water, so you can at least assume that locally-roasted coffee is optimized for the chemistry of your water. That's the opposite of Starbucks, which, according to Hendon, uses totally pure water to ensure a completely uniform taste across the country.

"A lot of dark art has gone into coffee," said Hendon. "This is some real science."

The study was published in the Journal of Agricultural and Food Chemistry.

SEE ALSO: Why You Should Be Drinking More Coffee — In One Chart

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With summer more or less here (stifle those sniggers, English readers), it seemed as good a time as any to examine the chemicals in sunscreen. It’s a product that many of us may take for granted, but you’ve got chemistry to thank for it preventing your skin turning lobster red in the summer sun. There are a number of chemical molecules used in currently available sunscreens, with the exact formulation actually depending on where in the world you live. Additionally, the chemistry of these molecules can help explain why sunscreen has to be reapplied periodically.

To understand the protection that sunscreen affords, we first have to understand what we’re trying to protect ourselves from. Sunscreen is designed to protect us from UV radiation from the sun; this has a shorter wavelength than visible light, and a lot of the energy emitted by the sun is in the form of UV, which can be divided into three categories. One of these, UVC (with a wavelength of ~290-100nm) isn’t a problem, as it’s absorbed by ozone in the atmosphere before it can reach the Earth’s surface. There are two other categories, however, UVA & UVB, which can cause damage to skin.

UVB (wavelength ~290-320nm) is responsible for around 5% of the UV radiation reaching Earth, with the majority of it also being absorbed by the atmosphere. It causes your skin to produce more melanin, which is what causes the tanning effect of sitting in the sun. However, it can also cause sunburn, and direct DNA damage, which can increase the risk of developing skin cancer. Sunscreen has been available as a product since around 1928, and most early sunscreens were formulated to screen the skin against UVB rays.

UVA (wavelength ~320-400nm) is responsible for the largest proportion of the UV radiation from the sun that reaches the Earth’s surface – approximately 95%. UVA can penetrate much deeper into the skin than UVB, down into the connective tissue. This causes wrinkling and premature ageing of the skin. UVA can also generate reactive species in the skin, and thus indirectly causing DNA damage, and contribute to an increased skin cancer risk. It was for a time considered relatively harmless in comparison to UVB, but now the damage it can cause is beginning to be understood, sunscreens have included different chemicals to also shield against this portion of the UV spectrum.

So, how does sunscreen work chemically? Both inorganic chemicals and organic (carbon based) chemicals can be used to afford protection. The two inorganic compounds used are titanium dioxide and zinc oxide. These protect the skin due to their particles forming a physical barrier, reflecting, or scattering, the UV radiation. The first sunscreens containing only these chemicals would have left a visible white layer on the skin.

In present day sunscreens, a combination of inorganic chemicals with organic chemicals are used. These organic chemicals work in a different way to protect us from UV radiation. Due to their chemical structures, their chemical bonds are able to absorb photons of UV light – this energy is then dissipated harmlessly in the form of heat. Variations in structure can lead to absorption at different wavelengths, meaning a mix of these organic chemicals is often used to ensure protection against the full range of UVA and UVB wavelengths.

These organic chemicals also explain, to an extent, why sunscreen has to be reapplied. Some of the organic chemicals used will be photostable; that is, they won’t break down when exposed to UV light. Some of them, however, will slowly break down as they absorb UV light over time – avobenzene, shown in the graphic, is one of the prime examples of this. Other chemicals can be added to help slow this breakdown, but it can be one of the reasons why it’s necessary to reapply sunscreen regularly. The more obvious reasons include the fact that even sunscreens that claim to be ‘water-resistant’ will still eventually wash off, which is why regulation now states sunscreens should also specify the length of time to which they remain water resistant.

If the the idea of this range of chemicals in your sunscreen has you concerned, it shouldn’t. All of them undergo a rigourous testing process before they are permitted to be used in sunscreens, and they all have limits on the amounts that can be used, to ensure that they’re nowhere near the levels that could be harmful. Some are absorbed more by the skin than others, but this is accounted for in safety testing, so it’s no cause for concern.

On a final note, interestingly, there are many more chemicals permitted for use in sunscreen in the EU (28) and Australia (34) when compared to the USA (17). In particular, a number of chemicals that block both UVA and UVB radiation have yet to be approved by the FDA despite being used for several years in other countries. This has something to do with the fact that, in the US, sunscreen is classed as an over-the-counter drug, whereas in other countries it’s classed as a cosmetic. As a consequence, the FDA’s approval process seems to be a little on the slow side – a new compound hasn’t been approved since 1999, and there are at least 8 new compounds waiting for approval, some of which have been waiting for over a decade.

SEE ALSO: CONSUMER REPORTS: The Best Sunscreens Aren't The Most Expensive Ones

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Everyone knows cats go crazy for catnip. It's an effect that's been noted in scientific literature as far back as the 18th Century, when scientists observed that cats seemed to be attracted to catnip when the plant was withered or bruised. Since then, research has managed to amass a little more detail on exactly why catnip affects cats in the way it does.

Firstly, a little background on what exactly catnip is. It's a plant that's a member of the same family as mint; in fact, one of catnip's alternate names is "catmint". When cats are exposed to the smell of catnip, their behaviour can take a turn for the strange. Their response to the scent has previously been categorised into four components:

• Sniffing.
• Licking, chewing and head shaking.
• Chin and cheek rubbing.
• Head-over rolling and body rubbing.

Source: Todd: Inheritance of the Catnip Response in Domestic Cats (1962)

As well as these, stretching, leaping, sexual stimulation and euphoria have also been noted. This behaviour is a response to a specific chemical, nepetalactone, which occurs in the plant. Nepetalactone and its isomers make up 70-99% of the essential oil that can be obtained from the catnip plant - 4aα,7α,7aα-Nepetalactone is the specific isomer responsible for the catnip effect, but for ease we'll just refer to it throughout as nepetalactone.

The exact mechanism through which the response is caused still isn't precisely known, but scientists have a pretty good idea of the general steps involved. Firstly, nepetalactone will enter the cat's nasal tissue, and there it will bind to certain receptors. These can then trigger particular sensory neurons to signal to other neurons, and eventually the brain; in particular, the "olfactory bulb", a region at the front of the brain responsible for processing smells. This region then signals other regions of the brain, including the amygdala, responsible for emotional responses to stimuli, and the hypothalamus, responsible for behavioural responses to stimuli. This results in the observed response in cats – a response that is actually similar to their response to natural sex pheromones.

The effect of catnip lasts for around ten minutes, and afterwards there will be a refractory period of around an hour where the cat will remain unaffected. Interestingly, not all cats are affected by catnip; the response is genetic, and autosomal dominant, which means if one parent passes on the gene, then the offspring will inherit the response. Around 70-80% of cats are affected by catnip, with the remaining 20-30% exhibiting no reaction to it whatsoever. Additionally, very young cats are also unaffected by catnip, until they reach sexual maturity. The figures stated for the age up to which they are unaffected are variable, but generally 6-8 weeks old is the most frequently mentioned.

Nepetalactone doesn't just affect domestic cats, either. It also has documented effects on lions, tigers and leopards, and additionally it can have effects on selected other animals. Notably, it can be used as a mosquito and fly repellent, and in humans it can act as a mild sedative and anti-spasmodic agent. It doesn't affect humans in the same way as cats, as the human brain is physiologically different from that of a cat.

If you're not a cat owner, or you've never seen the effect of catnip on cats, you can watch this clip from the BBC's "Weird Nature" series, which shows just how odd cats get in its vicinity.

SEE ALSO: People Are Going Crazy Over New York's Cat Café

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I never thought anybody took the phrase "chemical-free" seriously, because, obviously everything contains chemicals. But it has become a marketing slogan that a lot of people apparently subscribe to, and indeed some of the top Google search results, for example this site authored by a PhD, no less, pursue this angle without strenuously qualifying that the term is meaningless. 

But wait! Now a study has been done on all of the chemical-free products out there. If you like, check out the exhaustive manuscript over at Nature Chemistry. Here's the summary: 

Manufacturers of consumer products, in particular edibles and cosmetics, have broadly employed the term ‘Chemical free’ in marketing campaigns and on product labels. Such characterization is often incorrectly used to imply — and interpreted to mean —that the product in question is healthy, derived from natural sources, or otherwise free from synthetic components. We have examined and subjected to rudimentary analysis an exhaustive number of such products, including but not limited to lotions and cosmetics, herbal supplements, household cleaners, food items, and beverages. Herein are described all those consumer products, to our knowledge, that are appropriately labelled as ‘Chemical free’.

(SPOILER WARNING) If you don't have all of the 0 seconds required to read the list of products that are truly chemical-free, I'll ruin it for you: there aren't any. 

A funny (fake) study, to be sure; the term "chemical-free" is irritating and blatantly wrong. However, there is an argument to be made for expanded testing of industrial chemicals that have been introduced into humans' lives in increasing quantities in the past few centuries. The phrase "chemical-free," in encouraging uninformed chemophobia, detracts from that more nuanced line of thought, and doesn't help anybody. 

This article originally appeared on Popular Science

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As you settle down on your blanket to watch the July Fourth fireworks, you might be wondering: How do they make all those amazing colors and shapes?

We're here to tell you!

A firework is generally a tube or sphere holding explosives with a time-delay fuse leading to it. The explosives typically contain small balls (often about an inch in diameter) of colored explosives, called "stars" that blaze brightly in the sky once a certain amount of time has elapsed (which is how they determine how high in the sky it explodes).

The ignition of the explosive by a bursting charge in the center of the firework creates the explosion. The ignited explosive creates a high-pressure gas blowing the colorful stars outward.

The heat, height, and size of the explosion of the firework depends on the very specific chemistry of the explosives in the firework itself, but the colors are determined by chemistry.

"Everything you see at a fireworks display is chemistry in action," John Conkling told ACS Reactions. "The colors are all produced by very specific chemical mixtures."

Each star contains an oxidizing agent and fuel which create the intense heat and gas of the explosion, according to the American Chemical Society. The balls also contain a chemical that colors them, usually based on metals.

These metals create colorful lights in two ways. Some heat up and cycle through red, orange, yellow, and white colors depending how hot the explosion is, like how a traditional lightbulb heats up a wire until it glows.

The heat makes the atoms inside the wire move faster and faster and bump into each other more. These bumps give off light. The color of the glow can be controlled by how hot the firework is when it explodes.

Other fireworks create light by letting off specific colors. The metal atoms in the stars absorb heat energy from the explosive blast and release it as light, but the light released is specific to the atom in the mixture, because electrons that create the lights can only move between certain energy levels, giving off light with very specific colors.

This is how we get purple, blue, and green fireworks and is also how fluorescent lightbulbs work.

And how the stars are laid out within the cylinder or spherical firework itself determines what shape they make.

The stars are typically laid out in a particular shape — say, a smiley face — on a cardboard cylinder, which is then wrapped around the inside of the firework. Those stars will explode outward in the pattern they are placed in. Usually multiple shells are fired off at one time, because they can't control what angle at which the firework spews.

A spherical shell will expand outward equally in all directions. Different-colored stars can be studded in a specific pattern to make pretty presentations in the sky.

Not only does the firework look beautiful — it makes an amazing sound. That's a sonic boom created by the gasses inside the firework expanding greater than the speed of sound.

That firework is loaded into a second canister, called the mortar, that shoots it into the sky. That canister is usually powered by explosive as well, which is ignited under the firework, creating a lot of heat and pressure and shooting it high into the air. Some more modern displays use compressed-air mortars to fire the firework. This is more environmentally friendly and less dangerous.

All these explosives and awesome chemistry together and you get this:

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The supermassive black holes in the cores of most massive galaxies wreak havoc on their immediate surroundings. During their most active phases — when they ignite as luminous quasars — they launch extremely powerful and high-velocity outflows of gas.

These outflows can sweep up and heat material, playing a pivotal role in the formation and evolution of massive galaxies. Not only have astronomers observed them across the visible Universe, they also play a key ingredient in theoretical models.

But the physical nature of the outflows themselves has been a longstanding mystery. What physical mechanism causes gas to reach such high speeds, and in some cases be expelled from the galaxy?

A new study provides the first direct evidence that these outflows are accelerated by energetic jets produced by the supermassive black hole.

Using the Very Large Telescope in Chile, a team of astronomers led by Clive Tadhunter from Sheffield University, observed the nearby active galaxy IC 5063. At locations in the galaxy where its jets are impacting regions of dense gas, the gas is moving at extraordinary speeds of over 600,000 miles per hour.

"Much of the gas in the outflows is in the form of molecular hydrogen, which is fragile in the sense that it is destroyed at relatively low energies," said Tadhunter in a press release."I find it extraordinary that the molecular gas can survive being accelerated by jets of highly energetic particles moving at close to the speed of light.

As the jets travel through the galactic matter, they disrupt the surrounding gas and generate shock waves. These shock waves not only accelerate the gas, but also heat it. The team estimates the shock waves heat the gas to temperatures high enough to ionize the gas and dissociate the molecules. Molecular hydrogen is only formed in the significantly cooler post-shock gas.

"We suspected that the molecules must have been able to reform after the gas had been completely upset by the interaction with a fast plasma jet," said Raffaella Morganti from the Kapteyn Institute Groningen University. "Our direct observations of the phenomenon have confirmed that this extreme situation can indeed occur. Now we need to work at describing the exact physics of the interaction."

In interstellar space, molecular hydrogen forms on the surface of dust grains. But in this scenario, the dust is likely to have been destroyed in the intense shock waves. While it is possible for molecular hydrogen to form without the aid of dust grains (as seen in the early Universe) the exact mechanism in this case is still unknown.

The research helps answer a longstanding question — providing the first direct evidence that jets accelerate the molecular outflows seen in active galaxies — and asks new ones.

The results were published in Nature and are available online.

SEE ALSO: This Space Picture Changes Our Understanding Of How Black Holes Form

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In spite of its looks, this is not the lovechild of an accordion and an earthworm. It is actually a whole new material photographed in the middle of its creation process.

It's a crystalline material being soaked in a special acid solution. After some days of soaking, the pleats in this structure sloughed off. The resulting sheets were so thin, they were actually 2-dimensional—made of just one layer of atoms. They were among the first 2-dimensional polymers ever made by engineers, Chemical & Engineering News reports.

This week, two separate research teams publishedpapers announcing they had made the world's first verified 2-D polymers. The polymer sheets are akin to graphene, a material made of a single layer of carbon atoms. The difference is that polymers are made of atoms of several different elements in a repeating pattern. (In case you're curious, the two teams made polymers of slightly different atomic compositions.) A 2-D polymer has proved to be more difficult to make than sheets of graphene, which can sometimes even flake off the tips of pencils.

Both graphene and 2-D polymers are being studied for similar reasons, C&EN reports. They could do cool things in optics, and their super-tiny pores mean they could be used in high-tech filters. However, 2-D polymers still need work before they can be used in practical applications. For one thing, engineers will have to figure out how to make more of the polymers. Right now, just making a few grams of the stuff is a big feat, as it's taken the scientists years to get the process just right.

Both labs had previously made 2-D polymers, but this is the first time they've determined the exact structure of the polymers, C&EN reports. How were they able to visualize these vanishingly thin structures? They used X-ray crystallography, the same technique Rosalind Franklin used to visualize a single molecule of DNA in 1952. Franklin's X-ray image was crucial to James Watson and Francis Crick's insight into the true structure of DNA.

[Chemical & Engineering News]

This article originally appeared on Popular Science

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Anyone who's ever purchased an avocado will testify that, after taking several days to reach the point of perfect ripeness, they remain at that point for an incredibly short amount of time before morphing into a brown, sludgy mess.

As if to confound this problem, if you do catch them at the optimum ripeness, they turn brown incredibly quickly after being cut open if not eaten straight away. As always, there are chemical processes at work that are to blame for this occurrence.

The flesh of avocados is made up of mainly fatty acids, such as oleic acid and linoleic acid. They contain very little sugar or starch. Avocados don't start to ripen until they are picked from the tree, and if you put them into the fridge whilst still unripe, it can prevent them from ripening at all.

Putting into the fridge once they have reached the point of ripeness, however, can prolong the time at which they stay at this point for several days.

The rapid browning of avocado flesh is a consequence of its exposure to oxygen in the air, as well as the presence of phenolic compounds in the avocado itself.

In the presence of oxygen, an enzyme avocados contain, called polyphenol oxidase, aids the conversion of phenolic compounds to another class of compounds, quinones. Quinones are capable of polymerising, taking the smaller molecules and joining them together to form a long chain, to produce polymers called polyphenols. This polymerisation manifests itself as a brown colouration to the flesh.

The browning doesn't happen in the intact avocado, not only because the flesh isn't exposed to oxygen, but because the phenolic compounds are stored in the vacuole of the plant cells, whilst the enzymes are found in the surrounding cytoplasm. So, both damage to these cell structures and exposure to oxygen is required for browning to occur.

This browning isn't unique to avocados – the browning of many other fruits, such as apples, is also a consequence of this reaction. For the fruit, it's not a purely aesthetic process. Quinones are compounds that are toxic to bacteria, so their creation from phenolic compounds serves a practical purpose for the fruit by enabling it to last a little longer after exposure to oxygen before beginning to rot.

Browning of avocados can be prevented in several ways. One of the most effective is to rub lemon juice on the exposed flesh of the fruit. The enzymes which enable the enzymatic browning reactions to occur are sensitive to acidic conditions, and work much slower in them.

Another option is covering the avocado flesh tightly in cling-film. This prevents oxygen from reaching the flesh, and thus browning cannot take place.

Chilling the avocado in the fridge can also slow down the enzymes to an extent, as their activity is lower at lower temperatures.

The commonly touted method of leaving the seed pit in the avocado to prevent browning does work – but only on the part of the avocado that it's shielding from oxygen. Exposed areas of the flesh will still turn brown in time.

One final fact about avocados that I feel compelled to include here doesn't actually have anything to do with chemistry, but with the origin of the fruit's name. Whether because of its shape, or because they were thought to consider avocados to have aphrodisiac properties, the Aztecs named the trees it grew on 'āhuacacuahuitl' – which roughly translates as 'testicle tree'. If that isn't enough crude humour for your liking, then you'll be pleased to learn that 'guacamole' derives from the Aztec word 'ahuacamolli', which translates as testicle soup. Lovely.

It seems unclear as to which came first in the Aztec lexicon, and it's entirely possible that their word for avocado was used euphemistically for 'testicle', rather than the other way around. Either way, next time you're eating avocados or guacamole, it's a great fact to unsettle your fellow diners with.

SEE ALSO: Everything You Think You Know About Fish Oil And Omega-3s Is Probably Wrong

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Cream and sugar may not be the only additives in your morning cup of coffee. Tough growing conditions and rising demand are leading some coffee producers to mix in wheat, soybean, brown sugar, rye, barley, acai seeds, corn, twigs and even dirt.

The filler ingredients are natural and don't pose any immediate health risks for most people. But these additives could be a serious problem for people with soy or wheat allergies, said Suzana Lucy Nixdorf, a researcher at Universidade Estadual de Londrina in Brazil.

That's why Nixdorf developed a chemical test that can spot the difference between a batch of pure coffee grounds and a batch with unwanted ingredients. [10 Things You Need to Know About Coffee]

Coffee shortage

According to a 2013 report from the National Coffee Association, 83 percent of Americans drink coffee, up from 78 percent in 2012, and 63 percent said they drink it daily. The health benefits of coffee are still unclear.

As the demand for coffee increases, high temperatures, drought and a plant disease known as "coffee rust" are devastating Arabica coffee trees (Coffee arabica), which produce one of the most popular kinds of coffee bean and are grown in high-altitude farms in Central and South America.

Brazil, the world's leading producer of coffee, usually cranks out about 55 million 132-lb. bags (60-kilogram bags) each year. But a devastating drought that hit the country in January and lasted through March means Brazilian coffee growers may produce about 10 million fewer bags this year, according to the International Coffee Report issued by Informa Agra, Inc. The 10-million-bag difference translates to about 42 billion cups of coffee lost.

That doesn't mean caffeine addicts and coffee lovers should start hoarding coffee beans. Producers will likely be able to keep up with the growing demand, but they may have to rely more on lower-quality coffee, Gleidson Patto, a coffee cost analyst for Pinhalense, which makes equipment for farmers, told National Geographic News.

These trends will eventually drive up the price of coffee and are already encouraging "coffee counterfeiting," experts say, as fillers can make supplies of pure ground coffee last longer and boost profits.

"Less coffee makes prices rise," Nixdorf told Live Science. "You pay for coffee, but you aren't really getting coffee. That's the problem."

How to spot coffee fraud

Right now, one way to detect counterfeit coffee is to put the grounds under a microscope and try to spot the filler ingredients, Nixdorf said. But after roasting and grinding the beans, it becomes impossible to spot any twigs, berries or even dirt that blend in with the dark grounds. Nixdorf said it is common for Brazilian growers to produce very dark roasts so the filler ingredients blend in better.

Counterfeit coffee can also be identified by taste. For example, coffee grounds mixed with corn will produce sweeter tasting coffee, but the subtle flavor change can be hard to detect, Nixdorf said.

Nixdorf invented a new test that analyzes the chemical composition of coffee. She uses liquid chromatography, a process that creates a unique "fingerprint" stain for each ingredient. First, brewed coffee is sent through a pressurized pump. The coffee passes through a special paper filter. Each ingredient in the coffee will interact differently with the filter and will flow through it at different rates. The ingredients are separated out by the length and color of the stain they leave behind. The filler ingredients have different sugar levels than the natural compounds in coffee, and they leave behind distinct stains. Nixdorf said the test can tell if filler ingredients are mixed into coffee grounds with 95 percent accuracy.

For now, the chromatography test can be done only in a lab. Nixdorf recommended that consumers stick to whole-bean coffee or buy from reliable brands and coffee shops they trust.

Nixdorf's research was presented at the National Meeting & Exposition of the American Chemical Society in San Francisco last week.

Follow Kelly Dickerson on Twitter. Follow us @livescience, Facebook& Google+. Original article on Live Science.

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BI Answers: Is it OK to pee in the ocean?

If you've been to the beach this summer, chances are you probably had to pee, decided not to get out of the water, and just peed in the ocean.

Don't worry, you're not alone. Two-thirds of people surveyed by Proctor & Gamble (the company that makes Charmin toilet paper) said that they've peed in the ocean and almost half said they had done it more than once.

And after doing the deed, you may have had second thoughts because, at some point during your childhood, someone probably told you that pee attracts sharks. And you kind of believed them.

Does pee attract sharks?

We asked David Shiffman, a marine biologist who studies shark feed and conservation (also known by his Twitter handle @WhySharksMatter), about whether or not sharks are attracted to human urine.

His response was pretty blunt.

We were hard pressed to find academic research papers on the subject (although there are a whole bunch of papers written about shark kidneys), but we found some other accounts that support Shiffman's statement.

Vic Peddemores, senior research scientist, from the New South Wales Department of Fisheries in Australia told The Sydney Morning Herald: "I would have been dead a long time ago — there is no evidence that urine attracts sharks. I have been in the water close to large sharks like a tiger shark and have [p]eed, and it makes no difference."

National Geographic ran a series of experiments with sharks and divers to debunk several shark-related myths. They placed 2 divers in water, one holding a bottle of urine that slowly seeped into the water and another diver, in a separate area, without any urine:

Experiment Result: No reaction from sharks

We couldn't find peer-reviewed evidence, but it seems that when it comes to peeing in the water, you are probably fine as far as sharks are concerned.

Does pee pollute the ocean?

According to a recent video produced by American Chemical Society, it is A-OK to pee in the ocean.

Here's the quick chemistry lesson:

Human urine is 95 percent water. It also contains sodium (Na) and chloride (CL) ions — these are the same components that make up regular table salt (NaCL).

The ocean too is made up mostly of water (more than 96 percent) and an even higher concentration of sodium and chloride ions.

Both the ocean and urine also contain potassium (K).

One compound found in urine that is not found in the ocean is urea. It is an carbon-based compound that helps the body rid itself of nitrogen. But, as the video notes, the nitrogen in urea can combine ocean water to produce ammonium, a compound that acts as food for ocean plant life. You might even say that peeing in the ocean is actually GOOD for the plants and animals there.

Another point made in the video is that all of the animals that live in the ocean also pee in the ocean, including fin whales, which produce 250 gallons of pee each day. Even if every human on earth peed in the ocean at the same time, it would only create a tiny concentration of urea.

What about in the pool?

There are chemical reasons *not* to pee in the pool, according to a study published in Environmental Science and Technology. As Professor Ernest Blatchley of the Purdue University Engineering department explains in another YouTube video produced by the American Chemical Society, uric acid, which is found in human urine, interacts with chlorine (a disinfectant found in most pools) to create two dangerous compounds: cyanogen chloride and trichloramine. There is a little bit of evidence to show that these two compounds may contribute to respiratory problems and skin irritation in swimmers.

Though, a very thorough analysis from Ars Technica throws much of that chemistry out the window: The chemicals in the pool would have to be a much higher concentration — which would be very dangerous in itself — to make the reaction happen at a high enough level to make enough toxic byproducts that it would be dangerous. According to Casey Johnston:

In the end, we need a pool that is two parts water to one part chlorine and would probably burn the eyeballs out of your sockets and make your skin peel away from your bones (this calls for a pool boy who can only be criminally sadistic). If you and three million other people could get at this pool and unload your pee into it before your bodies melted, before the crowd crushed you to death, and before you drowned from the massive tidal wave of pee... yes, you could feasibly die of cyanogen chloride poisoning originating from chlorinated water and pee.

There's a lot worse things in the pool. The chemicals themselves send 5000 people to the ER ever year. The pool water is also loaded with nasty bacteria.

Where not to pee

Coral reefs! As with the relationship between human urine and sharks, it is difficult to find academic research on the impact of human urine on coral reefs. However, there is anecdotal evidence to suggest that it may be an issue. CNN interviewed Paul Sanchez-Navarro, Director of Centro Ecologico Akumal, an organization that monitors the impact of development on the reefs that thrive off the coast of Mexico's Quintana Roo province:

Pollution spilled into the sea by the thousands of hotels on the Mexican Riviera is "stressing" the coral reefs. "There are a lot of nutrients going into the ground water caused by treated water from the hotels and municipal waste water treatment plants," [Sanchez-Navarro] explains. "They inject the water into the ground and that makes its way into the aquifer... We've found way too many nutrients -- nitrates and phosphates -- and that comes from human waste, mostly urine." The result, says Sanchez-Navarro, is increased algae growth that effectively suffocates the coral, impeding its growth.

Small bodies of water! In 2012, TIME reported that a lake in northern Germany had been closed due to an "an algae bloom that poisoned over 500 fish," which some researchers thought was due to "a significant amount of human urine [in the lake]."

The bottom line? Pee in the ocean (but not on coral reefs) and it's unlikely that sharks will bother you. But don't pee in freshwater or small bodies of water because anecdotally, bad things might happen.

This post is part of a continuing series that answers all of your "why" questions related to science. Have your own question? Email science@businessinsider.com with the subject line "Q&A"; tweet your question to @BI_Science; or post to our Facebook page.

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Monosodium glutamate, more commonly known as MSG, gets a bad rap.

People claim that it's a toxin that causes headaches and sweating, and that it leaves you feeling lethargic and flushed. The thing is, most research shows that that's not true at normal dietary levels.

Despite its umami flavor boosting power, rumors have given MSG a reputation so bad that many Chinese restaurants frequently put up "No-MSG" signs to assuage customer's fear. Some customers then put soy sauce on their food, adding the missing MSG in after the fact. Because it's delicious.

The folks at the American Chemical Society decided to bust some MSG myths in their latest Reactions video.

What Is MSG And What Does It Do?

MSG's flavor enhancing properties were first discovered in 1908 by Japanese chemist Kikunae Ikeda, who wanted to understand how seaweed, which had been used by chefs for centuries, enhanced the flavor of foods.

Ikeda found that the key was a common amino acid — one of the building blocks for a protein — called L-Glutamate.

Glutamate is everywhere. It's found in many foods, including meat, dairy, and vegetables, and it's even produced in our own bodies naturally when we process food.

MSG's name tells us the key difference between glutamate and monosodium glutamate. MSG has a sodium atom that glutamate doesn't, which turns it into a salt form, making it easy to add to food. That's it.

Add it to food and it reacts with umami receptors on our tongue and allows us to better taste that savory flavor in whatever we're eating.

The Source Of The Myth

In 1968, a scientist wrote to the New England Journal of Medicine saying that he'd experienced something he decided to call "Chinese Restaurant Syndrome" after chowing down on Chinese food. He claimed he'd experienced "a numbness at the back of the neck that radiates to the arms and back," along with "general weakness and palpitation."

At the time, they decided to place the blame on the flavor additive.

But research over the next few decades didn't support the claim that a normal dose of MSG could cause the mysterious "Chinese Restaurant Syndrome" effects.

Instead, as the ACS says, the scientific consensus from that research is that "MSG can temporarily affect a select few when consumed in huge quantities on an empty stomach, but it's perfectly safe for the vast majority of people." 

So, a normal person may get temporary symptoms if they eat huge quantities of the stuff without any other other food. But no normal person would consume MSG in that way — it would make as much sense as eating tablespoons of salt, and cause the same reaction.

As for glutamate itself — as the ACS explains, it's one of the 20 amino acids that make up all naturally occurring proteins. Nothing to fear, here.

This graphic by Compound Interest breaks down all the research a little further:

So if MSG really isn't bad for you, why do people claim they experience these unpleasant effects after they eat food that may contain it?

In a lot of cases, it's simply a placebo effect. If you think you'll feel something, you can make yourself feel that way. Some other people may experience similar reactions if they're eating something new and have some sort of allergic reaction to that food, but MSG doesn't create antibodies that could cause an allergic reaction on its own.

Other people just eat way too much when eating out, or they are sensitive to the sodium levels of the foods.

There is a key thing to learn from this food myth, as explained in the ACS video below.

"If someone tells you that something is bad for you and you can't get a definitive answer as to why, it's your job to dig in and find out for yourself. This is what science is all about, not accepting something as truth without proper evidence."

Here's the video:

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