Flame retardant | When bright pink hides harmful products

Above the flames, firefighting planes drop huge tanks of bright pink flame retardant in just 20 seconds. This product has long been considered essential in fighting forest fires.

But new research has shown that the millions of liters of retardant sprayed each year to control fires come with a toxic load, because they contain heavy metals and other chemicals harmful to human health and the environment .

This toxicity poses a serious dilemma. Air tankers and their cargo are a powerful tool for controlling deadly fires. Yet as fires intensify and become more frequent in the era of climate change, firefighters are using them more often and thus releasing more harmful chemicals into the environment.

Some environmental groups have questioned the effectiveness of retardants and their potential for harm.

The effectiveness of flame retardants is difficult to measure because it is one of many firefighting tactics deployed during a large fire.

Once the flames are extinguished, it is difficult to determine the exact contribution.

A health burden added to smoke

The frequency and severity of wildfires have increased in recent years, particularly in the western United States. Scientists also found that fires in the region were moving more quickly in recent decades.

We must also consider the long-term health effects of exposure to wildfire smoke, which can enter the lungs and heart and cause illness. A recent global study of the health effects of air pollution from wildfires found that in the United States, exposure to wildfire smoke has increased by 77% since 2002.

Globally, it is estimated that forest fire smoke is responsible for 675,000 premature deaths per year.

Flame retardants add to these health and environmental burdens because they represent “a really, really thorny trade-off,” says Daniel McCurry, an assistant professor of civil and environmental engineering at the University of Southern California, who led the recent research on their heavy metal content.

The U.S. Forest Service said Thursday that nine large aircraft spraying retardants, along with 20 helicopters dropping water, were deployed to fight the Southern California fires, which have displaced tens of thousands of people. Amphibious aircraft, such as the Canadair CL-415, capable of skimming the surface of the sea or other bodies of water to refill their fuel tanks, are also used.

Two DC-10 aircraft, nicknamed “Very Large Airtankers” and capable of holding up to 35,583 gallons of retardant, are also expected to join the fleet soon, said Stanton Florea, a spokesman for the National Interagency Fire Center in Boise, Idaho. , which coordinates national efforts to fight wildfires throughout the western part of the country.

A screen between fire and oxygen

Sprayed upstream of the fire, the retardant coats the vegetation and prevents the supply of oxygen necessary to burn it, explains Stanton Florea. (A red-pink dye is added so firefighters can see the retardant in the landscape.) The retarder, usually made from salts like ammonium polyphosphate, “lasts longer; it doesn’t evaporate like water which falls,” he adds.

The new study by Mr. McCurry and his colleagues, however, found that at least four types of heavy metals, including chromium and cadmium, found in a common type of retardant used by firefighters, exceeded California’s safety requirements. hazardous waste.

Federal data shows that more than 1,665 million gallons of retardant were dumped on federal, state and private lands between 2009 and 2021.

From this figure, the researchers estimated that during these years, more than 400 tonnes of heavy metals were released into the environment following the suppression of fires, a third of which in the south of the California.

The federal government and the retarder’s manufacturer, Perimeter Solutions, both disputed that analysis, saying researchers evaluated a different version of the retarder. Dan Green, a spokesman for Perimeter Solutions, said the retardants used for aerial firefighting had undergone “extensive testing to confirm that they meet strict standards for aquatic and mammal safety.” “.

Nevertheless, these results explain why concentrations of heavy metals tend to increase in rivers and streams after wildfires, sometimes by several hundred times. As attention to firefighting products has increased, the Forest Service has established buffer zones around lakes and rivers, although its own data shows that retardant products continue to inadvertently drift into these waters.

In 2022, the environmental nonprofit Forest Service Employees for Environmental Ethics sued the government in Montana federal court, demanding that the Forest Service obtain a permit under the Water Act (Clean Water Act) to cover accidental spraying into watercourses.

The judge ruled that the agency must indeed obtain a permit. However, he authorized the continued use of retardant products in order to protect lives and property.

This article was originally published in the New York Times.

Read the original article from (in English; subscription required)