Environmentalists in Portland are still trying to clean tear gas residue from the streets as more than two months of protests continue throughout the city and officials worry the chemicals could pollute local waterways.

PORTLAND PROTESTERS, RIOTERS, TARGET POLICE WITH LASERS AND FIREWORKS OUTSIDE FEDERAL COURTHOUSE

Police and federal officers have come under heavy scrutiny for using pepper spray and tear gas to disperse crowds of demonstrators calling to defund the police and stop the use of force against minorities, particularly Black people.

Officers have said that protesters have thrown fireworks and other projectiles at police as well.

FILE - In this July 28, 2020, file photo, Federal officers deploy tear gas and crowd-control munitions at demonstrators during a protest at the federal courthouse in Portland, Ore. (AP Photo/Marcio Jose Sanchez, File)

But now officials are worried that toxins from the sprays could be harming the environment.

The Portland Bureau of Environmental Services cleaned and took samples from six storm drains last week around the federal courthouse and a building with a police station and jail that have been the epicenter of nightly demonstrations, many of which began peacefully and descended into violence as the night progressed.

Environmental officials aimed to prevent pollutants from reaching the Willamette River, which runs through downtown and is popular with kayakers, canoeists and boaters.

In this July 25, 2020, file photo, a protester carries an umbrella as federal officers deploy tear gas during a protest. (AP Photo/Marcio Jose Sanchez, File)

Officials said they’re testing for pollutants that are found in crowd-control agents such as the heavy metals zinc, lead, copper and chromium.

They are also trying to preemptively determine the possible impact if contaminants did flow into the waterways but so far, environmental agency spokeswoman Diane Dulken says, there is no evidence tear gas has reached the river.

State lawmakers are urging the U.S. Environmental Protection Agency and the Oregon Department of Environmental Quality to investigate “the public health and environmental risks of tear gas and other chemicals to people, wildlife, aquatic life and local air and water quality.”

Information about how much chemical reagents were used by officers as well as the compounds inside the gases have not been released to the public.

Some experts have also worried that the chemicals could also contribute to the spread of the coronavirus, as tear gas and pepper spray trigger coughing and sneezing from anyone impacted by it.

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The Associated Press contributed to this report.