SALEM, Ore. (AP) — In 2020, Black Lives Matter protesters were doused with tear gas, making them gasp for breath, their eyes feeling as if they were on fire. Bystanders, including children and pregnant women, were also exposed.

As police responded to mass protests across the nation two years ago with tear gas and other chemical munitions, more than a dozen U.S. senators asked the congressional watchdog to find out whether federal agencies have assessed how safe they are.

But the report by the Government Accountability Office skipped that question, dedicating only three paragraphs to the effects of “chemical irritants” and flash bangs. Both of the U.S. senators from Oregon — where the Trump administration deployed militarized federal agents — believe the report leaves too many questions unanswered and are calling for regulation of the tear gas industry.

The GAO report noted there were incidents in which less-lethal force may have been used by federal agents in violation of policy, but provided no details.

“This report is completely inadequate,” U.S. Sen. Jeff Merkley, D-Ore., one of the report requesters, said through spokeswoman Molly Prescott. “Congress and the American people deserve to know the details to better understand the significant issues and damage done by inappropriate use of less-lethal force.”

Portland, Oregon’s largest city, was an epicenter of the protests, with months of nightly, often violent demonstrations and vandalism following the murder of George Floyd by police in Minneapolis. Portland police used tear gas and pepper balls against protesters, and the Trump administration sent militarized federal agents to the city, starting in July 2020.

At least 1,315 federal officers were deployed to Oregon, according to a redacted document obtained by U.S Sen. Ron Wyden, D-Ore., from the Department of Homeland Security. They used more than a dozen different types of crowd-control devices, including 40 mm canisters loaded with tear gas or an oily extract of pepper plants, 40 mm “direct impact rounds” loaded with tear gas or pepper compounds, smoke grenades and foggers that emit chemical irritants, the document showed.

Law enforcement officials say tear gas, if used properly, is an effective tool for crowd control. On Sunday, police in Akron, Ohio, used tear gas against people protesting the shooting of Jayland Walker, a Black man who was killed by police on June 27 in a hail of gunfire.

Wyden isn’t satisfied with the GAO report and will keep pressing for answers, spokesman Hank Stern said.

Gretta Goodwin, a director of the GAO and lead author of the report released late last year, said her office was unable to answer the senators’ question on whether federal agencies have assessed the safety and effectiveness of tear gas and other chemical munitions, or their impacts on underlying health conditions.

“We start out by looking to see what information is out there,” Goodwin said over the phone. “We weren’t really able to find anything.”

Instead of government oversight, the multibillion-dollar industry regulates itself, a situation Wyden believes must end.

“He will push … for the appropriate federal agencies to oversee the manufacture of tear gas in our country, as well as to undertake an urgently needed non-industry and neutral study into the impact of these weapons on human health and the environment,” Stern said.

The Associated Press previously found few studies exist on the health effects of tear gas, with many being old and focusing on military personnel, who tend to be healthier and in better physical condition than the general public.

The GAO found that three federal agencies — the Marshals Service, Immigration and Customs Enforcement and the Secret Service — don’t even document when officers violate their agencies’ policies while using these weapons.

“That needs to be known. That needs to be more transparent,” Goodwin said.

Among controversial tactics and actions taken by law enforcement during Black Lives Matter protests: “kettling,” in which police seal off escape routes while blanketing people in tear gas and firing pepperballs; and firing projectiles point-blank at people. Donavan LaBella suffered severe injuries while peacefully protesting in Portland when he was hit in the face by a projectile fired by a federal officer.

Samira Green, pregnant at the time, found herself enveloped by tear gas fired by Portland police on June 2, 2020.

“Literally, you cannot breathe anything. It is clenched,” Green said, describing how her lungs seemed to seize up.

The U.S. Centers for Disease Control and Prevention warns that “long-lasting exposure or exposure to a large dose of riot control agent, especially in a closed setting” may cause blindness, glaucoma, severe chemical burns to the throat and lungs, respiratory failure and death.

The GAO report footnoted a 2016 study by Physicians for Human Rights and the International Network of Civil Liberties Organizations on health consequences of crowd-control weapons.

But the congressional watchdog agency should have noted that “our data is quite limited because there is no transparency about the weapons,” said Rohini Haar, co-author of the 2016 study.

Tear gas, which is banned in warfare by the Chemical Weapons Convention, is getting more powerful, Haar said. Silicon is sometimes added to make tear gas last longer in the air and on surfaces, even though its health effects are unknown, said Haar, an emergency room physician and researcher at the University of California School of Public Health in Berkeley.

Haar said it’s time for the U.S. government to either do its own research on riot-control agents or support others to conduct it.