Anybody who is wondering why such a fuss is being made about the close-range use of pepper spray on University of California-Davis protesters last weekend should read some of the research papers that have been written about the spray’s health effects.
The commercial-grade pepper spray used by policemen is nasty, nasty stuff.
It’s also dangerous.
Deborah Blum, a science writer (“The Poisoner’s Handbook”) and University of Wisconsin journalism professor, summarized what researchers have learned about pepper spray’s biological effects in a post last Sunday for the PLoS Blogs Network.
The first thing you should know, she points out, is that “commercial grade pepper spray leaves even the most painful of natural peppers (the Himalayan ghost pepper) far behind.”
Commercial-grade pepper spray is listed at between 2 million and 5.3 million units on the Scoville scale (the scale used since 1912 to measure the piquancy of chili peppers). That’s much hotter than the Himalayan ghost pepper (about 1 million Scoville units) and much, much hotter than the hottest pepper most Americans are familiar with, the habenero (150,000 to 350,000 Scoville units).
If you’ve ever accidentally rubbed your eyes after handling, say, an ordinary Jalepeno pepper (3,500 to 8,000 Scoville units), you know how painful capsaicin — the active compounds that make peppers hot — can be.
Now, imagine the pain you’d experience if sprayed with a chemical capsaicin concoction that’s roughly 600 times as hot.
The source of the danger
Yet, it’s not the pain per se, but how the capsaicin causes the pain — by binding directly to proteins in the heat-sensing nerve cells — that makes pepper spray so dangerous. Here’s Blum’s explanation:
[A]ny compound that can influence nerve function is, by definition, risky. Research tells us that pepper spray acts as a potent inflammatory agent. It amplifies allergic sensitivities, it irritates and damages eyes, membranes, bronchial airways, the stomach lining — basically what it touches. It works by causing pain — and, as we know, pain is the body warning us of an injury.
In general, these are short-term effects. Pepper spray, for instance, induces a burning sensation in the eyes in part by damaging cells in the outer layer of the cornea. Usually, the body repairs this kind of injury fairly neatly. But with repeated exposures, studies find, there can be permanent damage to the cornea.
The more worrisome effects have to do with inhalation — and by some reports, California university police officers deliberately put [pepper] spray down protesters’ throats. Capsaicins inflame the airways, causing swelling and restriction. And this means that pepper sprays pose a genuine risk to people with asthma and other respiratory conditions.
Indeed, pepper spray has been suspected over the years of causing a number of deaths of people in police custody, says Blum.
Other health risks
Commercial-grade pepper spray contains ingredients other than capsaicin that may also pose health risks, as a study published in 2004 by University of North Carolina researchers (and quoted by Blum) discovered:
Depending on brand, [a pepper spray] may contain water, alcohols, or organic solvents as liquid carriers; and nitrogen, carbon dioxide, or halogenated hydrocarbons (such as Freon, tetrachloroethylene, and methylene chloride) as propellants to discharge the canister contents. Inhalation of high doses of some of these chemicals can produce adverse cardiac, respiratory, and neurologic effects, including arrhythmias and sudden death.
Of the protesters sprayed by the University of California-Davis police, 11 had to be treated by paramedics at the scene and two were sent to a nearby hospital.
“Undoubtedly, these injuries will factor into another scientific study of pepper spray, another acknowledgement that top of the Scoville scale is dangerous territory,” writes Blum. “But my own preference is that we start learning from these mistakes without waiting another 13 years or more, without engaging in yet another cycle of abuse and injury.”
“Now would be good,” she added.