A spent tear gas canister on the street in downtown Portland.
A spent tear gas canister on the street in downtown Portland. Mathieu Lewis-Rolland
US Sen. Ron Wyden wants to know exactly what chemical weapons federal officers have been using on Portland protesters, when they were manufactured, and what their effects are on human health.

In a letter sent to Attorney General William Barr and Acting Secretary of Homeland Security Chad Wolf on Thursday morning, the Oregon Democrat wrote that reports of protesters having prolonged negative effects from tear gas "raises serious questions about the federal government's sustained use of tear gas during the occupation of Portland."

"Residents of downtown Portland, including the houseless community, were exposed to these dangerous chemicals regardless of whether they took part in the protests," Wyden wrote. "This response would be disturbing under any circumstances but it is completely unacceptable in the middle of a global respiratory pandemic."

Wyden's request comes a week afterUS Rep. Earl Blumenauer and Oregon State Rep. Karin Power sent a joint letter to national and state environmental agencies, seeking information about the environmental and public health impacts tied to tear gas use.

Wyden's letter asks for clarification about the policies—or lack thereof—that allow agents with the Department of Homeland Security (DHS) the ability to use such copious amounts of tear gas during their occupation of the city.

"What processes do your agencies and their subcomponents follow when determining whether to use tear gas or riot control agents?" the letter reads. "Are [Department of Justice] and DHS officials required to indicate that they have exhausted all other options before using tear gas or riot control agents?"

Wyden's letter twice cites reporting from OPB that found more than two dozen protesters who believe that regular exposure to tear gas has caused irregularities in their menstrual cycles since the protests began.

The letter also highlights an ongoing Kaiser Permanente study on the health effects of tear gas and smoke grenade exposure that launched at the end of July and is soliciting data from Portlanders exposed to gas through an anonymous survey. As of Wednesday, the survey had already received more than 1,500 responses.

While little is known about the longterm effects of nightly exposure to tear gas, Wyden's letter notes that the Center for Disease Control and Prevention (CDC) lists death alongside choking, vision problems and respiratory failure as a potential risk of exposure.

Even less is known about the dangers of exposure to expired tear gas, which Portland protesters have faced for weeks.

Neither the Portland Police Bureau (PPB) nor DHS have confirmed that their officers have used expired tear gas or other riot control agents against protesters. Wyden is seeking not only an answer to that question, but also information on if and how federal agencies track when those chemicals do expire.

Wyden's letter does not mention the copious use of tear gas by Portland officers, which has been ongoing for more than two months.

The senator is asking for a response from Barr and Wolf by August 31.