The use of tear gas by Egyptian security forces has drawn a lot of attention.

Particularly since the tear gas canisters used in Egypt have “Made in the USA” labels.

To find out more about what’s in the canisters, Marco Werman speaks with Sven-Eric Jordt, assistant professor of pharmacology at Yale University.

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Marco Werman: The use of tear gas by Egyptian security forces has drawn a lot of attention, particularly since as we mentioned, the tear gas canisters used in Egypt have “Made in the USA” on the labels. To find out more about what’s in the canisters we turned to Sven-Eric Jordt. He’s an assistant professor of pharmacology at Yale University.

Sven-Eric Jordt: The major tear gas currently used is called CS gas that was developed in the 1920s actually, and deployed in the military and also for riot control in the ’50s and ’60s. This is a compound that is actually a solid that is burned or is sprayed, contained in an organic solvent. This is a compound that activates very fine pain sensing nerve endings in the cornea of our eyes and also in the mucous membranes of our airways. So, CS tear gas is the major gas currently used for example, in the riots in Egypt. In the United States at UC Davis, pepper spray was used and…

Werman: Right, differentiate it. Is it the same thing?

Jordt: No, it’s not the same thing. It actually uses another compound, it’s called capzasin, that’s the pungent ingredient in chili peppers. That’s why it’s called pepper spray, that’s either isolated from chilis or synthetically produced, but it has a similar effect. It’s just not as corrosive and chemically aggressive as CS tear gas.

Werman: And pepper spray and CS or tear gas, are the effects permanent in any way? I mean mostly we think of them as temporary.

Jordt: Usually people recover quite well after being exposed, however, there have been frequent reports, especially for the CS tear gas, of skin injuries and burns. And people, especially civilians who have preexisting conditions such as asthma, bronchitis can have severe effects, life-threatening effects that have been reported in many cases where people were exposed.

Werman: What about some claims that nerve agents were introduced into the chemical mix in the tear gas canisters in Cairo. Does that seem correct to you?

Jordt: I doubt that, frankly, however, I think it’s possible that there was so much tear gas used that people got really highly toxic exposures and interpret that as nerve agent deployment. But I doubt that this was truly used.

Werman: Break it down though, what does it feel like because you’ve been sprayed with tear gas when you were a student in Germany.

Jordt: I experienced this myself. It causes really severe initially burning of the eyes and the nose. You start tearing profusely, your involuntarily and your eyelids get closed shut by muscle cramps in the eyelids. The next stage is basically that your airways fill with mucous and it’s not the upper airways, but also the lower airways, and you have the sensation of suffocation and panic actually. So that can lead to incapacitation and serious anxiety and fear. So it’s not a very pleasant experience.

Werman: Sven-Eric Jordt, assistant professor of pharmacology at Yale, thanks very much.

Jordt: You’re welcome, thanks.

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