New study finds widespread reports of menstrual irregularities among Portland protesters

By Rebecca Ellis (OPB)
April 28, 2021 8:53 p.m.

The authors found over half of the 1,650 respondents who potentially menstruate reported an impact of some sort.

Last summer, in the midst of nationwide racial justice demonstrations that regularly ended with law enforcement emitting clouds of tear gas, anecdotes started cropping up online of protesters convinced regular exposure to the chemical had disrupted their menstrual cycles.

As of Tuesday, those anecdotal reports are no longer relegated to the realm of social media and news outlets. Researchers with Portland’s Kaiser Permanente Center for Health Research have published what they say is the nation’s first ever peer-reviewed study exploring the connection between periods and tear gas.


The study, published in BMC-Public Health Journal, surveyed 2,257 adults who had been exposed to tear gas during demonstrations in Portland between July 30 to Aug. 20. The vast majority had encountered the gas at a protest, while about 150 had been exposed in their homes or elsewhere. The online survey asked participants about physical and psychological health issues, whether the participant had sought out health care services and experienced any menstrual changes, among other questions.

The survey found a majority of respondents who potentially menstruate reported irregular periods after tear gas exposure.

The authors found 54.5% of the 1,650 respondents who potentially menstruate reported a menstrual impact of some sort. The most commonly reported issues were increased menstrual cramping (36.6%), unusual spotting (27.8%), increased bleeding (23.6%), and more days of bleeding than expected (18.9%).

“Many respondents noted that after their exposures, their menstrual cycle started days or weeks earlier or later and lasted longer, compared to their typical cycle,” the study stated.

A graphic showing the changes in menstrual health associate with tear gas exposure.

A graphic showing the changes in menstrual health associate with tear gas exposure.


OPB reported last July on the accounts of 26 protesters, ranging in age from 17 to 43, who believed regular exposure to tear gas has caused irregularities within their menstrual cycles. Both federal and local law enforcement regularly blanketed protests with tear gas over the summer to disperse crowds. Portland Mayor Ted Wheeler, who also serves as the police commissioner, banned Portland police from using CS gas, a widely used kind of tear gas, in most situations in September.

At the time, OPB could find little scientific research into whether tear gas agents could impact a person’s hormones.


Britta N. Torgrimson-Ojerio, the lead author of the study, said the report does not answer the question of whether chemicals in tear gas can impact the endocrine system, but fuels a push for this to be taken up in future research.

“We can’t say anything definitive,” said Torgrimson-Ojerio, a researcher at Kaiser Permanente Center for Health Research. “Other than that this is widespread and widely reported.”

The findings of widespread health issues after tear gas exposure come with a few big caveats. The health issues were self reported, and the participants were self-selected. Perhaps most significantly, a protest is hardly a controlled environment. There are a host of other factors that could influence the findings aside from tear gas — among them aggressive law enforcement tactics and the general stress of a protest environment.

The paper acknowledged this stress could be another major culprit for irregular periods. Rising levels of cortisol, the body’s primary stress hormone, are known to upend normal menstrual cycles.

But Torgrimson-Ojerio emphasized that stress could be a factor in all health issues participants reported. Nearly all respondents reported physical or psychological health issues after exposure. Nearly half reported an issue with their lungs or chest and nearly a third reported gastrointestinal issues in the days after exposure. The study also found more than half of survey respondents received or planned to receive healthcare services.

“It’s interesting this question seems to come up mostly in this change reported with menstrual impact, and this isn’t questioned so much with the other systems that are impacted: digestive system, respiratory system, nervous system,” she said. “We have no reason to believe that stress impacted these findings more than any other.”

She also noted that stress is not usually linked to reports of increased bleeding, unusual spotting and increased cramping.

Theo Blackman, a 25-year-old who protested almost nightly last summer, believes a summer of tear gas exposure is the reason their period vanished.

Blackman said they have not taken any hormones in the last year, are not pregnant and haven’t experienced any dramatic life changes. But, in the last 10 months, they have had no spotting, no cramping and no period.

Blackman said they were skeptical the new study would serve as a call-to-action in the healthcare industry, which has a legacy of overlooking the health needs of female and transgender patients.

This week, they made an appointment with a doctor to talk about their period and potential lingering effects of tear gas exposure. Blackman said they felt dismissed by the physician, who thought pregnancy was more likely.

“They don’t listen to me,” they said. “I really hope people are actually paying attention to what this is going to be doing. This is a lifelong repercussion, possibly.”