Some forest fire extinguishers contain heavy metals and can pollute the environment

Water isn’t the only thing used to put out flames in fire-prone areas. Wildland firefighters also use chemical or synthetic extinguishing agents. Researchers to report in Environmental Science and Technology Letters investigated whether these suppressants are the source of elevated metal levels sometimes found in waterways after forest fires are extinguished.

Several of the products they researched have at least one high level metalincluding chromium and cadmium and may contribute to post-fire increases in the environment.

“Forest fires are associated with the release of toxic heavy metals into the environment, but so far these metals natural sources like soil,” says Daniel McCurry, the study’s principal investigator. “We now know that fire retardants may contribute to these metal releases.”

Products designed to prevent wildfires fire activity before and after water vaporizes, includes fire retardants, water enhancers and foams. As wildfires become more frequent and intense, greater volumes of water are required to extinguish them, along with chemical and synthetic suppressants sprayed from the ground and dropped from aircraft.

Although manufacturers identify most of the active ingredients in suppressants, some components are proprietary. In addition, previous researchers have observed increased concentrations of potentially toxic metals in soil and runoff following wildfires.

So McCurry and his colleagues at the University of Southern California wondered whether the suppressants contained metals and could contaminate the environment.

The researchers tested samples from 14 fire extinguisher products sold by commercial vendors. They analyzed samples for 10 metals known to be toxic or regulated by the US Environmental Protection Agency (EPA).

Each product contained at least one metal with concentrations that exceeded EPA’s Maximum Contaminant Level guidelines for drinking water.

Specifically, two extinguishing products classified as fire retardants contain eight metals (chromium, cadmium, arsenic, lead, vanadium, manganese, antimony, and thallium) that far exceed the EPA’s drinking water guidelines. And one of the delays exceeded California’s hazardous waste regulations for three of those metals.

The researchers say these results show that fire retardants can pollute the environment aquatic environment and potentially drinking water if these products enter water bodies.

The volume of fire retardants fell forest fires In the United States between 2009 and 2021, researchers found that the total amount of metals applied varied from year to year, but generally increased over time. For one Southern California wildfire, they estimate that elevated cadmium concentrations in a nearby stream can be explained by 31% of the fire retardant used to contain the fire.

They say these results suggest that firefighting activities may contribute to elevated levels of metals in the environment, but that more work is needed to determine the potential risks to people and humans. environmental health.