'Forever chemicals' may have polluted 20m acres of US cropland

[lordsummerisle]

theguardian.com

About 20m acres of cropland in the United States may be contaminated from PFAS-tainted sewage sludge that has been used as fertilizer, a new report estimates.

PFAS, or per- and polyfluoroalkyl substances, are a class of about 9,000 compounds used to make products heat-, water- or stain-resistant. Known as “forever chemicals” because they don’t naturally break down, they have been linked to cancer, thyroid disruption, liver problems, birth defects, immunosuppression and more.

https://www.theguardian.com/environment/2022/may/08/us-cropland-may-be-contaminated-forever-chemicals-study

[bucolic_frolic]

1. " don't naturally break down"

Ever? Not like in 500 years? That would be hard to believe. Shoe leather can take millennia to decompose, but it eventually makes the turn. Forever would be good as gold. Preservative wise.

[NNadir]

2. It has been shown that there are a number of defluorination enzymes known, but the kinetics...

...are limited by the rarity of the organisms involved. Many of this organisms end up producing trifluoroacetate the world concentrations of which are increasingly in all environmental matrices.

The OP is a little misleading in the sense it seems to limit the case to farmland fertilized with sewage sludge. PFAS substances are now found everywhere because of their long environmental half-life.

There are two possible sinks for mineralization, conversion to CO2 and insoluble CaF2. One is thermal; at very high temperatures PFAS decompose. The other is radiolytic. In order for these processes to be effective, they must be operated in continuous flow situations, which would be generally practiced in a sustainable world, but not the world in which we live.

[Phoenix61]

3. They do break down very, very slowly. They have been

used for over 80 years. Developed by DuPont and used in Teflon to keep things from sticking. One of the reasons we are hearing about them in the environment now is they are measured in parts per trillion and the technology wasn’t available to measure that small of an amount of anything.

[hunter]

4. Some of the worst PFA pollution is from fire fighting foams...

... especially on military bases where they were used regularly in practice drills.