Fact check: Does tear gas become more dangerous once expired?

The issue: When police fired tear gas at protesters in Raleigh in late May, a comment heard on a police scanner went viral, appearing to show officers discussing expired gas provided by the Cary Police Department. The audio clip led to discussions that also spread rapidly on social media about whether expired tear gas could turn into something more dangerous — like cyanide, a fast-acting and potentially deadly chemical.

Why we’re checking this: After protests around the state and country, and

changes to some law enforcement agencies’ policies on use of force, tear gas will remain a concern for many. As confusion and rumors spread across social media, it’s important to understand the facts.

What you need to know: The Cary Police Department disputes what officers appear to discuss on the scanner, saying it did send about 16 officers in response to a call for assistance from Raleigh on May 30, but did not deploy nor provide anyone with gas.

“Any gas that we maintain within the agency, when it reaches its shelf life it loses its potency, so it becomes weaker,” said Shawn Anderson, deputy chief of police for the CPD. He said that they would not use nor give another department any less potent gas.

Raleigh Police had not provided any comment in response to multiple News & Observer requests at the time of publication. The N&O first reached out to the Raleigh Police Department on June 2. Despite eight additional follow-up requests over the subsequent 20-day period, and correspondence with a department spokeswoman, RPD still had not provided information about the incident.

But according to Sven-Eric Jordt, a researcher at Duke University who has studied the effects of tear gas since the mid-2000s, research on expired tear gas is sorely lacking. While Anderson may be correct that it becomes less potent, without proper study it’s not entirely clear.

“It might be less effective, but we also need to monitor really what kind of compounds are formed,” Jordt said.

James Bonner, a toxicologist at NC State University, said while he was unsure whether the chemicals would grow more toxic or potent with age, expired chemicals should not be used.

“Otherwise, why would you have an expiration date?” he said. “There’s an expiration date for a reason.”

According to Jordt, as they expire, tear gas canisters do become more dangerous to use. As the combustive component breaks down, it can cause inaccuracy in its deployment, or result in a higher concentration of chemicals if they are unable to properly disperse. These canisters could pose a threat to police and civilians alike.

As talk of expired tear gas spread online, many concerns centered around the deadly chemical cyanide and claims that it could be released by expired canisters. But experts said the levels of cyanide found in tear gas are unlikely to cause any immediate harm.

“The levels are in the same range as what a smoker inhales when he or she smokes a cigarette,” Jordt said. “It’s certainly not advised to inhale cyanide in any form, but I don’t think this is really at a level where it would cause serious injury or death.”

Instead, Bonner warned that the main danger with tear gas is its impact on those of older age, or who have weak respiratory systems, who could suffer more severe harm. This danger, he said, is present in tear gas whether or not it has expired.

“Every individual is not like one another,” Bonner said. “If you have a pre-existing condition like asthma, or you’re older, or something like that, then it could be very serious. You don’t want to be exposed to something like that.”

While we don’t know whether it was deployed in the Raleigh protest, several instances of expired gas use in other countries have cropped in recent years. During protests against government corruption in Iraq last year, Reuters reported canisters with an expiration date of 2014 were deployed. Medical volunteers who spoke with the news organization claimed the gas was making people choke.

Expired tear gas was also reportedly used in Hong Kong, where protesters’ opposition to an extradition bill broadened to encompass government corruption and a push for democracy. In August, Bloomberg News reported that the city’s police pledged to stop using expired tear gas after photos of expired canisters spread on social media.

Our sources. Here’s where we found information and research on this topic.

The Annals of the New York Academy of Sciences article on the effects of tear gas

Bloomberg article on tear gas use in Hong Kong protests

Reuters article on anti-government protests in Iraq

This story was produced by The News & Observer Fact-Checking Project, which shares fact-checks with newsrooms statewide. It was edited by politics editor Jordan Schrader and Managing Editor Jane Elizabeth. Submit a suggestion for what we should check, or a comment or suggestion about our fact-checking, at bit.ly/nandofactcheck.

This story was originally published June 29, 2020 at 1:39 PM.