What Are the Long-Term Health Effects of Tear Gas?

FERGUSON, MO - AUGUST 17: Tear gas fills the street as a demonstrator walks through the haze during protests over the killing of teenager Michael Brown by a Ferguson police officer, on August 17, 2014 in Ferguson, Missouri. Despite the Brown family's continued call for peaceful demonstrations, violent protests have erupted nearly every night in Ferguson since his August 9, death. (Photo by Scott Olson/Getty Images)
Photo: Scott Olson/Getty Images

In recent photos from Ferguson, Missouri, clouds of tear gas hang ominously in the air, and protestors tend to each other after getting doused with a chemical weapon that’s been banned in war, but not in domestic riots. (Though reports indicate that tear gas has not been used the last two nights.) 

The immediate symptoms of exposure to tear gas are clear: intense pain in the eyes that cause secretion of tears in the eyes and mucous in the airways. Some victims feel as if their airways are flooding with water, a sensation akin to suffocation or drowning, explained Duke University associate professor of anesthesiology Sven Jordt.

But what do scientists know about what happens to victims of tear gas in the following weeks, months, or even years? Surprisingly little. Jordt has studied tear gas for nearly a decade, and Science of Us spoke with him to find out more about the emerging research in this area.

What do we know about the long-term effects of tear gas exposure?
At this time, there are no long-term studies published monitoring long-term outcomes in tear-gas-exposed individuals and groups. But our research shows that tear-gas exposures cause severe inflammation that can take weeks to resolve, and also chemical burns to the skin.

Do you know why there aren’t yet any long-term studies?
The issue is it’s usually a small number of people who are exposed and affected. It would require a massive effort to follow these exposure victims over years or decades.

But there are now efforts under way by doctors in Turkey to start long-term studies of exposure victims. They have patients in Istanbul they have been following over the last two years, and have shown some data at meetings I’ve attended in the U.S. on the effects on the respiratory system in the lungs of people who have been exposed. People basically had asthmalike conditions, or signs of chemical lung injury, that were very clear.

What does that mean — “signs of chemical injury”?
It basically means reduced respiratory capacity — so, reduced oxygen in your blood, which can lead to asthmalike conditions.

Again, we don’t yet know what the effect over the course of these victims’ lives will be. But I’m concerned. If there are severe respiratory exposures, this can lead to a decline in lung function that may not be observed initially — that has been found in people who have been exposed to similar agents in industrial accidents, for example.

And has tear gas really been linked to miscarriage?
In Bahrain, women experienced miscarriages after tear-gas exposures. But it’s not clear that the tear gas caused this, because miscarriage can certainly happen during severe distress. The issue is that there is no follow-up research on this.

This research that has been done recently on tear-gas exposure has been done in Turkey. I expect we can’t directly compare that to what’s happening in Ferguson, right?
Right. In these incidents in the Middle East, they likely inhaled large amounts and therefore may have suffered lung injury. But it has to be in a really, really dense environment, like these dense Middle Eastern cities such as Istanbul, for those large amounts to be ingested. Ferguson, like many American cities, is suburban, more spread out. So there’s less of a risk there.

So, no, it cannot be really compared in these environments in Turkey. But Ferguson is scary; tear gas was deployed against crowds with children and the elderly, which we know are especially vulnerable populations. So it’s certainly a concern. 

This conversation has been lightly edited.

What Are the Long-Term Effects of Tear Gas?