As students carried David Busco to a house near the grounds of an Occupy demonstration in 2011, the pepper spray coating his face and mouth moved through his sinuses and throat. It burned everything it touched, damaging cells in the outer layer of his corneas. It inflamed his airways, causing swelling and restriction; his breathing was strained. The water his friends poured on him exacerbated the problem, and the burning didn't ebb until they scrubbed him down with dish soap. Busco told reporters it felt like "thousands of pieces of glass shooting into your eyes."

Pepper spray, made with the active ingredient oleoresin capsicum, is a nonlethal weapon regularly used by law enforcement to control crowds. Like tear gas, it contains capsaicin, the active ingredient that makes peppers hot. Pepper spray comes in an aerosol can to spray a thick, focused line, while tear gas is often deployed like a grenade so it can envelop a large group of people.

Many activists are all too familiar with it. "We've come to expect tear gas and have become accustomed to it, which is messed-up in its own right," said DeRay Mckesson, a civil rights activist who participated in Black Lives Matter protests in Baltimore and St. Louis.

Given pepper spray's role in police-brutality deaths, and its potential to do long-term damage to the body, its extremely frequent documented use is more alarming than the descriptor "nonlethal weapon" may suggest. "Being tear-gassed in America" while "protesting the police killing people is unreal," Mckesson told Mic.

Moreover, tear gas and pepper spray aren't the only supposedly less harmful law-enforcement tools that have the potential to cause serious damage to the body. It's important to know offhand what the most common crowd-control weapons used by law enforcement will do to a body. If a city cuts cellphone service to quell protests, protesters won't have the chance to call for help.

Why pepper spray burns so badly

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Pepper spray in the eyes burns 10 times worse than habanero pepper. That's thanks to that oily extract, oleoresin capsicum, which comes from some pepper plants and is used in everything from salsa to anesthetics to the weaponized sprays we're talking about here.

Since there isn't a hard and fast rule for OC content in a pepper spray, potency varies from 1% to more than 12% — meaning the really hardcore stuff can be about 30 times more potent than the watered-down versions. It's measured on the Scoville scale, the same way Buffalo Wild Wings measures its sauces. For perspective, a habanero pepper is generally in the 200,000 to 350,000 range of Scoville units. The pepper spray used by police tops out at a brutal 5.3 million units.

Pepper spray's effects can include apnea, abnormally low blood pressure, respiratory arrest, inability to breathe or speak and burning in the anus.

Think of the residual heat left over when you taste an extremely hot sauce. Pepper spray works the same way, continuing its burn for around an hour. In most cases, pepper spray comes out like a Super Soaker stream of what feels like wet, coarse sand. When it hits a moist membrane, like the eyes or skin, the burning takes over, further exacerbated by air exposure, which is why it hurts so bad to open your eyes after they've been hit.

Like anyone with a sensitive stomach can tell you, the extreme heat of the OC content translates to other areas of the body. A 1999 paper from the North Carolina Medical Journal, titled "Health Hazards of Pepper Spray," said pepper spray's effects can include apnea, abnormally low blood pressure, respiratory arrest, inability to breathe or speak and burning in the anus — most of which is leagues more painful than the Blazin' Wing Challenge.

"Pepper spray is 45 minutes of pure hell," Steve Ijames, a former assistant chief of the Springfield, Missouri, police department, told Mic. For decades, Ijames tested pepper spray on incoming law enforcement agents during police and security-force training. "It's so you know what you're capable of handling once you get sprayed," he told Mic. Feeling sympathy for the victims of pepper spray is "a small component," but the biggest reason Ijames pepper-sprayed fellow cops was "to educate them about what they'd need to do if they got sprayed, and give context of when to use it on somebody."

Tasers don't electrocute. Here's what they're really doing to your body.

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When that college student famously shouted "Don't tase me, bro!" at oncoming security, we all watched it and assumed the man was being electrocuted, or having volts of electricity shot through his body — something that could kill a person.

From 2001 to 2013, there were 540 deaths by police stun guns in the United States.

But Human Electro-Muscular Incapacitation devices, commonly called Tasers after the popularity of Taser International's models, actually work by sending low-current pulses, manipulating your reflex neurons, causing a bunch of uncoordinated muscle responses that result in tetanic muscle cramps.

When you have what's called adequate probe spread, or when the HEMI barbs cover about 12 inches of their target, the device scrambles the electronic signal from brain to muscle.

"It's the tensing of muscles, lack of control, and it feels like you can't breathe," Ijames told Mic. "Taser pain is a consuming, controlling kind of pain."

Flash-bang grenades could blow your jaw off.

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A flash-bang grenade is the foreplay of law enforcement action. The idea behind it is to create a disorienting distraction with a bright flash, a loud noise and an elevated atmospheric pressure so that the human brain would perceive a rapid stimulus without explanation. It's something that happens in less than the blink of an eye, but overloads the brain with data to create a six- to eight-second period of disorientation, according to Ijames.

But flash-bangs have also been known to blow off limbs.

"There have been many legal cases involving blown-off eyes and faces and hands."

"[Flash-bangs] are way less reliable than the other tools we've been talking about," Ijames told Mic. "They kill people in close contact. There have been many legal cases involving blown-off eyes and faces and hands."

Like a high-powered firework, the flash-bang's explosion can be deadly — and carries the potential for serious abuse. During a 2014 drug raid in Georgia, police dropped one in a baby's crib, leaving the infant in a coma, his body covered in burns.

Ijames estimated flash-bangs work half of the time — with varying results.

"From TV, people have this crazy idea they're like stun grenades," Ijames told Mic. He explained that the noise level, about 170 decibels, isn't even enough to rupture an eardrum. "The risk is contact."

Rubber bullets are still fired out of shotguns.

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The history of less-than-lethal bullets actually goes back over 100 years, when Singapore police launched sawed-off broom handles at rioters. British soldiers used rubber bullets a few decades ago against the Irish Republican Army. Even some crowd-control grenades are full of rubber pellets. In the United States, however, their use is few and far between. Instead, they're replaced by what are colloquially called "beanbags": cloth-filled lead shot, which can cost about $8 a round.

"Police departments don't have a lot of money ... [and] plastic bullets are about $26 a shot," Ijames told Mic, though similar "baton" rounds can be found for about $22 per round. "A lot of what we do in policing isn't because it's the best; it's because it's the least worst."

Billions of dollars go into firearms in the U.S. But when you're a cop and use a lot of bullets, keeping those expenses down takes a lot of corner-cutting. "In the Springfield police department, where I worked, the SWAT team uses 37 mm polyurethane projectiles," Ijames told Mic. "Much more accurate with longer range. We've shot hundreds of people with them since the '90s. In 2001, the patrol shot 32 people with them."

Even beanbags, used as weapons, can cause a lot of damage. A 2004 study by the National Institute of Justice showed eight people were killed in 373 instances of using beanbag "impact munitions." The study reported 782 of the rounds caused injury, about 10.8% of them causing real damage when they didn't need to use lethal force.

"A lot of what we do in policing isn't because it's the best, it's because it's the least worst."

This is where things get tricky. For some weapons to continue to be nonlethal, range becomes a factor. When you're shot with a nontraditional bullet from a certain distance, you can still die. The same way a paintball stings at long range and causes welts point-blank, a beanbag bullet or rubber pellet can cause serious bodily harm, or even death, if used carelessly or abusively.

Even weapons meant for close combat can be enough to cause fatal injuries. A study conducted by Amnesty International and Inquest revealed that, from 2001 to 2013, there were 540 deaths by police stun guns in the United States.

There's a program of the Department of Defense called the Non-Lethal Weapons Program that decides what does and doesn't count as nonlethal, and when the risk for serious injury becomes too high. Its coverage area is specifically for the U.S. military. But when local police forces have access to the same weapons used to fight enemy soldiers overseas, it's important to know how those tools are regulated.

There's a program to decide what nonlethal weapons could kill you.

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When the U.S. military needs a new nonlethal technology for use in missions, it solicits third-party weapons developers. One of the most important variables, risk of significant injury, is the potential of a nonlethal weapon to directly cause injury requiring medical treatment, permanent injury or death.

According to the Defense Department's Direction 3200.19, risk of serious injury is the parameter used to describe reversibility of nonlethal weapons as they relate to human effects — that is, the ability to return whatever was shot, whether an inanimate object, animal or person, to whatever state it was in before impact. The Non-Lethal Weapons Program is in place to make sure that when you buy a box of rubber bullets, they aren't going to put a bloody hole in their target.

"If you want your device to never injure someone, it will probably also never work."

Wesley Burgei, a human effects scientist with the Non-Lethal Weapons Program, is part of the team that determines these factors. When a weapons developer wants to know the parameters for building a flash-bang or a type of less-than-lethal bullet, it's run through the Joint Capabilities Integration and Development System, the procedure for defining and evaluating criteria for future defense tools. It's Burgei's data that tells the military whether it's going to cause a bump or a hole.

The Joint Capabilities Integration and Development System is the formal Department of Defense procedure that defines acquisition requirements and evaluation criteria for future defense programs. Department of Defense

The RSI scale accounts for anything nonlethal, whether it's a "dazzling laser," a bright light used to warn oncoming vehicles that they're approaching a military checkpoint, or something used to protect an embassy or Defense Department facility — especially when the intent of the visitor isn't immediately apparent.

"It's a trade-off of accepting risk," Burgei told Mic. "In many things we do, when you say, 'I want it to work 90% of the time' ... you're asking yourself, what risk to a target am I willing to accept while still accomplishing the mission? If you want your device to never injure someone, it will probably also never work."

Burgei has worked to help weapons developers have guidelines for the RSI through applied research — or shooting nonlethal bullets and bombs at targets to figure out how they'll impact human flesh.

Another model from JCIDS Department of Defense

"We really want RSI to be zero, because we're intending to not cause injury," Burgei told Mic. "But given the situation, you have to understand what [injury] could you accept."

For blunt impact munitions like rubber bullets, Burgei says, you measure the peak pressure on a force plate, or a sensor calibrated to know how bad the impact would be on a human body. Burgei's data would tell you that, hypothetically, if you want your ranged weapon to have less than a 10% RSI, it shouldn't be fired from less than 15 meters away.

But here's the scary part: The Department of Defense, along with Burgei, defines the guidelines of these technologies under the assumption that they won't be abused. They often are.

Weapons developers give their creations safety ranges. At close range, these nonlethal weapons cease to be safe and enter a high risk of significant injury gray area. These tools are powerful methods of keeping fatalities down when they can be helped, but to use them requires sound minds on the part of law enforcement.

Meanwhile, protests in response to police killings of people of color are becoming more widespread, and police are resorting to more severe methods to contain the crowds. "The continuum of weapons is really wide," Mckesson told Mic. "The sound cannon [Long Range Acoustic Device], to pepper balls, to smoke bombs, to pepper spray, to tear gas — the gamut has been used over the past year against protesters." And if police "haven't used it directly," Mckesson said, "they have had it ready to be used at a moment's notice."

No manufacturer or government agency wants lethal technology in the hands of people like Daniel Pantaleo or Timothy Loehmann. To wield the technology to protect lives takes courage and critical thinking — traits that not every officer possesses.