Matt is an environment correspondent.

PFASImage source, Getty Images
Image caption, PFAS have been found in rain in Tibet

There are levels of chemicals that exceed safety levels in the rain.

Non-stick pans, fire-fighting foam, and water-repellent clothes are some of the things that are made from these synthetic substances.

They persist in the environment for a long time.

Scientists say there is no safe place to avoid them.

It is vital that the use of these substances is restricted quickly.

Scientists are concerned about the health risks of PFAS. They are concerned about the increase in the number of PFAS.

Poly- and perfluoroalkyl substances are referred to as PFCs.

Food packaging, non-stick cookware, rain gear, adhesives, paper and paints are just a few of the hundreds of everyday products that contain fluorine based compounds.

Image source, Getty Images
Image caption, Fire fighting foams often contain PFAS chemicals

Concerns about the safety of drinking water have been raised.

The current safety level in England and Wales is not exceeded by the levels found in water samples in England.

A new study suggests that levels of one of the chemicals in the class can exceed US drinking water advisories.

Evidence shows that the world's soil is contaminated.

According to the findings of the study, there is no safe space on Earth to avoid these substances.

"We argue here that we're not within this safe operating space anymore, because we now have these chemicals everywhere, and these safety advisories, we can't achieve them anymore," said Prof IanCousins.

I am not saying that we will all die of these effects. We are in a place where you can't live anywhere on the planet and be sure that the environment is safe.

This is definitely cause for concern, but there are some things to consider.

Advisory levels are not legally enforceable.

Some scientists believe that the health risks of these chemicals should not be taken lightly.

Scientists say that exposure to high levels may be associated with an increased risk of some cancers and fertility issues in children.

Other studies have found no correlation between the two.

Image source, Markus Frey
Image caption, Scientists drilling for ice samples in Antarctica to see how far PFAS have travelled

The evidence in the new research paper shows the need for a precautionary approach for those who have been working with it for a long time.

The levels are higher in the rain than they are in the air. Prof Crispin Halsall from the University of Lancaster said that the chemicals would have a significant impact on human health. He was not part of the study.

How will that happen? It's going to come out over time, because we're exceeding those concentrations which are going to cause some harm, because of exposure to humans in their drinking water.

It is possible to remove the chemicals from the water.

Image source, Getty Images
Image caption, Rainwater all over the planet exceeds US safety guidelines say scientists

It is very difficult to get below the US advisory levels.

Over the past two decades, the safety advisories have been lowered as scientists have gained more knowledge.

Problems have arisen due to the presence of these chemicals in the soil.

In the Netherlands, the infrastructure ministry set limits on the amount of PFAS in soil.

70% of building projects were stopped because of this. The guidelines were loosened after protests.

This type of relaxation of safety levels is likely to happen when water is contaminated.

Prof Ian Cousins said that if those guidelines were applied everywhere, they wouldn't be able to build anything.

The US drinking water advisories are not practical to apply.

There is nothing wrong with the risk assessment. You cannot apply those things. It is not possible to apply any of those guidelines.

Image source, Getty Images
Image caption, A Netherlands construction site - many projects in the country had to stop because of restrictions on PFAS

According to the study authors, the main challenge with these chemicals is their persistence.

Two decades ago, some harmful PFAS were phased out, but they still persist.

Sea spray can carry small particles into the air and then back to land.

The inability to breakdown in the environment means that PFAS are now found in remote areas.

There are moves at European level to restrict the use of these chemicals and to find more benign replacements, but there are also hopes that industry will move away from using these chemicals.

"We want our products to last a long time while we use them, that's why we need persistent chemicals and substances."

There are progressive actors as well. When I see these industries working together, I'm very hopeful.

The research has been published.

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