People exposed to teargas or other crowd-control chemicals during recent Gaza and immigration protests say the toxic substances have caused long-lasting health effects, including disrupting their menstrual cycles and inducing hormone imbalances, according to accounts collected by the Guardian and reports from protesters in Michigan and Los Angeles.
More than a dozen people across three protests reported the health effects. Among other issues, they say they have experienced intense cramping and increased bleeding during menstruation, along with irregular menstrual cycles, weight gain and fatigue.
The accounts were connected to teargas exposure during protests in 2024 and 2025. They come after a 2021 study found that at least 900 women in Portland, Oregon, who were exposed to high levels of teargas during a Black Lives Matter protest experienced similar health problems.
Still, few regulations around the substances’ uses exist, and the ongoing health effects are “really, really frustrating”, said Sammie Lewis, an Ann Arbor, Michigan, community organizer who was active in the pro-Palestinian protests that took place at the University of Michigan in the spring of 2024. They say they are developing a study in partnership with a U-M PhD student examining health problems stemming from the use of Deep Freeze, a substance combining teargas and pepper spray, to break up a Gaza protest encampment at the University of Michigan in May 2024.
“I feel like my body is failing me and I’m out of touch with it,” Lewis said. “This is something that I’ve never gone through. I feel like I don’t have a lot of control, and it has been detrimental to my mental health.”
Police used teargas on campuses across the country to disperse the protests that erupted at US universities in the spring of 2024, including in Michigan, Arizona and Florida.
Heavier exposures to teargas have been found by the US Environmental Protection Agency to be linked to cancer and organ damage, and the US army found that people exposed to it are at “2.5-times greater risk of being diagnosed with acute respiratory illness”.
However, there is a dearth of research on the effects of chemical sprays on women, said Asha Hassan, an assistant professor of obstetrics, gynecology and women’s health at the University of Minnesota who co-authored the 2021 Portland study. Some protesters sued the city of Portland over its use of teargas and other crowd-control devices, resulting in a $250,000 settlement.
The substances’ chemical make-ups are proprietary, but Portland city staff found significantly elevated levels of barium, copper, lead and zinc in storm drains near where the gas was deployed.
The EPA has set advisory health levels, but no enforceable limits exist.
Lewis collected accounts from a dozen people who reported health effects from teargas at the University of Michigan. The Guardian also spoke to a woman who experienced similar issues after attending a Los Angeles protest against Ice in early June 2025 and who reported hearing similar accounts from other women. Issues were also reported to the Guardian by a protester against Ice in Newark, New Jersey.
Lewis described how U-M police descended on a pro-Palestinian encampment and “hosed” protesters with Deep Freeze. One held the canister to Lewis’s face and moved it up and down Lewis’s body, they said. It caused “excruciating” burning, Lewis said, but the worst of their problems came in the incident’s wake.
They said they had started their period the night before the encampment raid, and that it stopped that day, which was unusual. It came back three weeks later, and since then has frequently returned every three weeks. Lewis said they rarely experienced cramps prior to the incident, but suffered from the “worst cramps I’ve ever had” afterwards. Meanwhile, they have been fatigued and gained weight that has been difficult to lose despite eating well and exercising.
Lewis said they got their blood checked and learned that their progesterone and estrogen levels were “way off”.
About 12 out of the approximately 20 people who menstruate who were at the encampment say they have had issues, Lewis said. One merely hugged another who had been sprayed, and suffered some health effects, they said.
Symptoms of those people only lightly exposed to the spray have begun to subside, Lewis said, but others, like them, who were heavily exposed, continue to suffer.
“Between the physical effects of everything from the raid, and the mental effects of the repression, it has been hard to piece my life back together and heal,” Lewis said.
In New Jersey, a protester who was outside Delaney Hall, a New Jersey Ice facility, said she was sprayed by a federal agent with a substance that was in an unmarked black can.
The protester, who declined to use her name for fear of retaliation, said she had painful cramps for several days after the incident. Since then, her period was late and heavier than usual.
The health effects are “very scary”, the protester said, and added she fears the long-term effects.
“It’s giving me a healthy amount of anxiety because I just don’t know what passed through my body,” the protester said.
In Michigan, a student involved with the encampment there said she was “drenched” by Deep Freeze and suddenly got her period two weeks early, halfway through her cycle. It was accompanied by flu-like symptoms and nausea, and she said the consistency of her blood was much thicker than usual. The issues remain, though they began to subside in recent months.
In a statement, the University of Michigan did not respond to accounts of side effects from teargas. It “welcomes dissent and the expression of the broadest array of ideas – even those that may be upsetting to some, or critical of the university” but that “no one is entitled to disrupt the lawful activities or speech of others, disrupt operations, or threaten the safety of the community”, a spokesperson wrote.
Anecdotal evidence collected in Bahrain, the occupied Palestinian territories and elsewhere has linked teargas to miscarriages, but the precise impact on reproductive health has been difficult to prove given methodological challenges. “Tear gas has so many components that any one of them could potentially cause fetal harm,” Rohini Haar, a doctor with Physicians for Human Rights and a lecturer at the University of California at Berkeley law school, told Scientific American. She added that separating the effects of teargas on pregnancy from other variables like stress, mental health issues, impacts of arrest and components other than the main compound found in teargas is “near impossible”.
Hassan, the co-author of the Portland study, says she is currently working on a peer-reviewed study to check whether those exposed during Black Lives Matter protests suffer from pregnancy complications. She believes more research is desperately needed.
“There is a need for more safety investigation into what the potential impacts are, and it should be considered in the context of policy and how law enforcement is utilizing tear gas,” she said.
