No one really knows what’s in fire retardant – but it’s affecting fish and plants

No one really knows what’s in fire retardant – but it’s affecting fish and plants

 29 November 2017

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USA: So far this year California has dropped 15 million gallons of fire retardant on burning forests and hillsides across the state.

But here’s the thing: No one really knows what it’s made of — or its full environmental impact. The ingredients are protected as trade secrets under federal law, but they’re affecting plants and animals and humans.

The chemical powder is a flame retardant, used to slow down fast-moving fires to clear the way for ground firefighters. It’s considered a vital firefighting tool, but this year California has dropped a new record amount, that’s double what it was three years ago.

So, with the increase in drops, what are the repercussions on the environment?

Matt Weiser from News Deeply spoke to A Martinez about the four things worth considering about California’s increased use of fire retardant.


The retardant powder ingredients are protected as trade secrets under federal law.

“But we do know that the main ingredient is some type of ammonia compound,” explained Weiser, “mixed with a gelling agent of some sort that is meant to cause this chemical to stick to plants.”


Effect on fish

Weiser cited a study that can kill salmon at “less than one percent of the concentration at which it is applied.” In other words, fire retardants remain deadly to fish even after they’re diluted in their environment.

Effect on plants

Because their main active ingredient is ammonia, a key ingredient in fertilizer, it’s been found that these retardants become a powerful fertilizer for plants in the aftermath of fires. This is true for invasive non-native plants in particular.

Many of these plants are “better able to colonize burned areas after a fire,” said Weiser. “They actually feed on the ammonia in these retardants and they can crowd out the native plants.”

The result of this phenomenon changes the habitat of the affected area considerably.

What about humans?

There are no studies that look into the effect on humans once the retardants are applied. However, they can be harmful to those who mix it.

“These things are usually delivered as a powder and then mixed with water before being pumped onto a plane or a helicopter. If the people mixing them on the ground breathe the power excessively, it can cause health problems.”


“One of the situations we have with a lot of wildfires these days is they’re occurring closer and closer to developed areas and that’s largely because we’re developing in areas that are more likely to burn.”

These areas are known as wildland-urban interface. A lot of burning happened in wildland-urban interfaces during the October Sonoma and Napa county fires. The fires that devastated Santa Rosa occurred in areas that had burned in a large fire 50 years ago, but there were no homes there back then.


An alternative has been developed by a company in Georgia called “Hazard Control Technologies,” according to them, their retardant is less harmful than the ones being used now by Cal Fire and the U.S. forest service.

But don’t expect to hear about this new Georgia retardant being used by the forest service anytime soon.

“It doesn’t meet their testing protocol. The company claims that the test protocol is outdated and needs to be revised.”

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