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(Almost) Everything You Need to Know About Tear Gas

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What started as a protest against the demolition of Istanbul’s Gezi Park has boiled over into broad anti-government unrest in cities across Turkey. Almost everywhere, the protestors have been met with heavy resistance from riot police and torrents of tear gas. Here’s a crash course in the chemical weapon of the moment.

What is it?

Tear gas isn’t one specific chemical, and it’s usually not even a gas, despite the name. There are a few different compounds that are used as “lachrymatory agents.” Most of them are solids at room temperature, and get mixed with liquid or gas dispersal agents for use.

The variety favored by the Turkish police is known as CS gas, which is made from a powdery compound called 2-chlorobenzylidene malononitrile and a liquid solvent (often methylene chloride), mixed into an aerosol spray.

Where did it come from?

Tear gases in general are something that militaries have been messing around with since World War I. Both France and Germany developed and deployed lachrymatory irritants in battle, but there was evidently a bit of a learning curve. According to the U.S. Army’s Combat Studies Institute, the Germans fired some 3000 tear gas shells during one day of fighting in 1914, but the British troops on the receiving end “suffered no ill effects and never suspected they were under chemical attack.”

In just a few years, the Germans had gotten a handle on things and were using tear-inducing gases to great effect. In 1916, they fired 2000 shells into a French trench system and 2400 French soldiers—blinded, coughing and crying—quickly found themselves surrounded by German troops in protective goggles.

CS gas would come a few decades later. Its active component, 2-chlorobenzylidene malononitrile, was synthesized by American chemists Ben Corson and Roger Stoughton in 1928 and tear gas using it (CS = Corson + Stoughton) was developed and tested during the 1950s and '60s.

What does it do?

Tear gases irritate the mucous membranes of the eyes, nose, mouth, and lungs, and cause tearing, coughing, burning, and stinging sensations, chest tightness and difficulty breathing. At higher concentrations, exposure can cause stomach irritation leading to vomiting and diarrhea.

According to German toxicologist Uwe Heinrich, dispersing the gas at a concentration of one milligram per cubic meter will cause symptoms of irritation. From there, things go sour pretty quickly. A concentration of 10 mg per cubic meter can force trained soldiers to retreat from an area. Ten to 20 mg/m3 or higher can cause serious injury or, depending on the victim and conditions of exposure, death. In one incident reported in a Swiss medical journal, an otherwise healthy adult man was exposed to a tear gas grenade containing just one gram of CS while inside a building. He quickly developed toxic pulmonary edema, a condition where excess fluid collects in the air sacs of the lungs and causes difficulty breathing, and recovered only after weeks of medical treatment.

Sounds nasty. Shouldn’t stuff like this be illegal?

It is. Kind of. Tear gases were used in warfare through most of the 20th century until 1993, when the Chemical Weapons Convention banned the production, stockpiling and use of chemical weapons in battle. The international treaty doesn’t apply to nations’ domestic law enforcement, though, so police officers from Turkey to Texas are free to spray it at civilians.

Repressive Middle Eastern governments really love the stuff, don’t they?

Boy, do they ever! During a protest just last month, Turkish police used 14 tons of water mixed with CS components, and Prime Minister Recep Tayyip Erdoğan has earned the nicknames “Chemical Tayyip” and “Gasman” thanks to police and security forces’ rampant use of tear gas.

Bahraini police also have a gas problem, to the point where the foreign policy writer Steve Fake says the country has “raised the global bar on the usage of tear gas to unprecedented heights. It has become the Tear Gas Regime.” A report released by the organization Physicians for Human Rights last year says, “Preliminary analysis of data suggests that the majority of Shi’a neighborhoods (comprising 80% of all neighborhoods in Bahrain) have been exposed to toxic chemical agent attacks at least once per week since February 2011.” [Emphasis theirs]

How do you treat tear gas exposure?

If you’re outside, the best antidote to any breathing problems is fresh, untainted air, and time. For high dose exposure or exposure in enclosed spaces, bottled oxygen or certain asthma medications may be administered to ease difficulty breathing. Any exposed skin should be washed with soap and water and eyes should be flushed with sterile water or saline solution. A flyer circulated at the Occupy Wall Street protests also recommended spraying the eyes, mouth and throat with a 50/50 mix of water and Maalox. (Though this specifically mentions capsaicin-based tear gases. Not sure if it works for other types, and I’m  not looking to test it out.)

Is there anything else you wanna know about tear gas? Have other questions about current events or sciencey things? Email askmatt@mentalfloss.com. 

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Big Questions
What Do Morticians Do With the Blood They Take Out of Dead Bodies?
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Zoe-Anne Barcellos:

The blood goes down the sink drain, into the sewer system.

I am not a mortician, but I work for a medical examiner/coroner. During an autopsy, most blood is drained from the decedent. This is not on purpose, but a result of gravity. Later a mortician may or may not embalm, depending on the wishes of the family.

Autopsies are done on a table that has a drain at one end; this drain is placed over a sink—a regular sink, with a garbage disposal in it. The blood and bodily fluids just drain down the table, into the sink, and down the drain. This goes into the sewer, like every other sink and toilet, and (usually) goes to a water treatment plant.

You may be thinking that this is biohazardous waste and needs to be treated differently. [If] we can’t put oil, or chemicals (like formalin) down the drains due to regulations, why is blood not treated similarly? I would assume because it is effectively handled by the water treatment plants. If it wasn’t, I am sure the regulations would be changed.

Now any items that are soiled with blood—those cannot be thrown away in the regular trash. Most clothing worn by the decedent is either retained for evidence or released with the decedent to the funeral home—even if they were bloody.

But any gauze, medical tubing, papers, etc. that have blood or bodily fluids on them must be thrown away into a biohazardous trash. These are lined with bright red trash liners, and these are placed in a specially marked box and taped closed. These boxes are stacked up in the garage until they are picked up by a specialty garbage company. I am not sure, but I am pretty sure they are incinerated.

Additionally anything sharp or pointy—like needles, scalpels, etc.—must go into a rigid “sharps” container. When they are 2/3 full we just toss these into one of the biotrash containers.

The biotrash is treated differently, as, if it went to a landfill, then the blood (and therefore the bloodborne pathogens like Hepatitis and HIV) could be exposed to people or animals. Rain could wash it into untreated water systems.

This post originally appeared on Quora. Click here to view.

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Why Does Asparagus Make Your Pee Smell Funny?
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The asparagus has a long and storied history. It was mentioned in the myths and the scholarly writings of ancient Greece, and its cultivation was the subject of a detailed lesson in Cato the Elder's treatise, On Agriculture. But it wasn't until the turn of the 18th century that discussion of the link between asparagus and odorous urine emerged. In 1731, John Arbuthnot, physician to Queen Anne, noted in a book about food that asparagus "affects the urine with a foetid smell ... and therefore have been suspected by some physicians as not friendly to the kidneys." Benjamin Franklin also noticed that eating asparagus "shall give our urine a disagreeable odor."

Since then, there has been debate over what is responsible for the stinky pee phenomenon. Polish chemist and doctor Marceli Nencki identified a compound called methanethiol as the cause in 1891, after a study that involved four men eating about three and a half pounds of asparagus apiece. In 1975, Robert H. White, a chemist at the University of California at San Diego, used gas chromatography to pin down several compounds known as S-methyl thioesters as the culprits. Other researchers have blamed various "sulfur-containing compounds" and, simply, "metabolites."

More recently, a study demonstrated that asparagusic acid taken orally by subjects known to produce stinky asparagus pee produced odorous urine, which contained the same volatile compounds found in their asparagus-induced odorous urine. Other subjects, who normally didn't experience asparagus-induced odorous urine, likewise were spared stinky pee after taking asparagusic acid.

The researchers concluded that asparagusic acid and its derivatives are the precursors of urinary odor (compared, in different scientific papers, to the smell of "rotten cabbage," "boiling cabbage" and "vegetable soup"). The various compounds that contribute to the distinct smell—and were sometimes blamed as the sole cause in the past—are metabolized from asparagusic acid.

Exactly how these compounds are produced as we digest asparagus remains unclear, so let's turn to an equally compelling, but more answerable question:

WHY DOESN'T ASPARAGUS MAKE YOUR PEE SMELL FUNNY?

Remember when I said that some people don't produce stinky asparagus pee? Several studies have shown that only some of us experience stinky pee (ranging from 20 to 40 percent of the subjects taking part in the study, depending on which paper you read), while the majority have never had the pleasure.

For a while, the world was divided into those whose pee stank after eating asparagus and those whose didn't. Then in 1980, a study complicated matters: Subjects whose pee stank sniffed the urine of subjects whose pee didn't. Guess what? The pee stank. It turns out we're not only divided by the ability to produce odorous asparagus pee, but the ability to smell it.

An anosmia—an inability to perceive a smell—keeps certain people from smelling the compounds that make up even the most offensive asparagus pee, and like the stinky pee non-producers, they're in the majority.

Producing and perceiving asparagus pee don't go hand-in-hand, either. The 1980 study found that some people who don't produce stinky pee could detect the rotten cabbage smell in another person's urine. On the flip side, some stink producers aren't able to pick up the scent in their own urine or the urine of others.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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