Cadmium, Arsenic, Chromium Among Toxic Metals In Fire Suppression Chemical Dropped From Planes

[hatrack]

The US federal government and chemical makers have long concealed the contents of pink wildfire suppressants widely spread by firefighting aircraft to contain blazes, but new test results provide alarming answers – the substances are rife with cadmium, arsenic, chromium and other toxic heavy metals. The suppressants are a “major” source of toxic pollution that causes heavy-metal levels to spike in the environment, and the products themselves contain metal levels up to 3,000 times above drinking water limits, the peer-reviewed research found.

The government and chemical makers have claimed up to 20% of aerial suppressants’ contents are “trade secrets” and exempt from public disclosure, so while there has been suspicion of the substances’ toxicity, the study is the first to confirm the metals’ presence.

It also highlights the tension between protecting human health and property from wildfires by spraying highly toxic substances – about 440m gallons were sprayed between 2009 and 2021, the study noted. “As rates of aerial fire retardant application have grown, likely so too have loadings of toxic metals released into the environment from their use, a trend which may intensify if wildfire frequency and intensity continues to increase,” the University of Southern California authors wrote.

The suppressants are a mix of water, fertilizer, and undisclosed ingredients, while the pink color comes from added dye to show firefighters where it has been sprayed. Metals are likely used as anti-corrosion agents to prevent the plane’s tankers (Ed. - sic) from disintegrating, they authors wrote. The mix works by coating vegetation and lowering the amount of oxygen that could fuel the fire.

EDIT

https://www.theguardian.com/us-news/2025/feb/13/us-wildfire-suppressants-toxic-study