30 May 2023

Worrying data in the U.S. on PFAS contamination in soil


In New Hampshire, the presence of fluorine-based substances was detected in all soil samples taken by researchers. These products, known as PFASs and contained in pesticides, are typically difficult to dispose of

by Matteo Cavallito


Pollution levels from fluorine-based substances in soil and air are reportedly higher than previously thought. This is suggested by a U.S. survey conducted in the state of New Hampshire. The researchers, in particular, found high levels of PFAS or Per- and polyfluoroalkyl substances, in a hundred soil samples taken at shallow depths in areas far from the best-known sources of contamination.

Because of this, writes The Guardian, “the chemicals are thought to largely have gotten there through the air.” Mindi Messmer, a former member of the New Hampshire House of Representatives, quoted by the British newspaper, called the results of the investigation ‘pretty disturbing’ highlighting the risks to people’s health. “However it got here, it’s there and it is widespread,, ” she explained. “It’s the fault of decades of regulatory inaction.”

Fluorine products do not go away easily

PFASs are not surprisingly called forever chemicals because of their persistence in soils. “Such chemicals are both highly stable and useful in products designed to repel grease and water. But it also means they do not readily biodegrade,” the journal Scientific American wrote, highlighting the relevance of this characteristic.

These substances are typically found in fluorinated pesticides – those that contain one or more fluorine atoms in their molecular structure – which are considered particularly effective in combating plant pests.

What favors their antiparasitic action is precisely their recognized chemical stability, which promotes their prolonged action while limiting their disposal margins. It is estimated that the half-life of some fluorinated pesticides – that is, the time it takes for their presence in the environment to be halved after spraying -can be as long as 2 1/2 years. The EPA, the U.S. Environmental Protection Agency, defines “persistent” as pollutants characterized by a half-life of not less than 60 days.

The study

In New Hampshire, “At all 100 locations, samples were collected from 0 (land surface) to 6 inches in depth. At 50 locations, samples from 6 to 12 inches depth were collected, while at 6 of these locations soil profiles were collected in 6-inch increments to a maximum of 36 inches in depth,” the study states. The analysis showed the presence of PFAS in all the observed samples.

As the Guardian points out, “No limits on PFAS in soil exist federally or in New Hampshire, but the levels are millions of times higher than the US Environmental Protection Agency advisory drinking water threshold for some common PFAS compounds.” Also according to the newspaper, “Many of the contaminated sites would trigger remediation in Massachusetts, New Hampshire’s southern neighbor, which set limits for individual compounds in soil between 0.3 and 2 ppb.”

A global problem

Fluorine pollution is not just an American problem. Last year, the Guardian still recalls, research by Stockholm University found that the presence of PFAS in rainwater on a global scale exceeds the safety limits set by several national and supranational authorities. Including those of the United States, Denmark, the Netherlands and the European Union. And that “atmospheric deposition also leads to global soils being ubiquitously contaminated.”

Also of concern is the expansion of sales of pesticides containing PFAS. In the late 20th century, the market share of fluorinated products stood at around 9 percent. Today, by contrast, they are booming. To the point of accounting for almost 70 percent of all new pesticides introduced worldwide from 2015 to 2020.