A pair of substances harmful to health, known as perfluoroalkyl and polyfluoroalkyl substances (PFAS), are spreading through the atmosphere and can already be found in rainwater and snow, even to the ends of the Earth.
This is the conclusion reached by researchers from Stockholm University, Sweden, and ETH Zurich, Switzerland, who reviewed the new safe limits for these substances, such as the cancer-causing PFOA, and compared them with atmospheric measurements across the globe.
“Under the latest U.S. guidelines on PFOA in drinking water, rainwater from around the world would be considered unsafe to drink,” said Ian Cousins, the study’s lead author and a professor in the University’s Department of Environmental Sciences, in a statement.
Supply of drinking water sources
“Although we don’t often drink rainwater in the industrial world, many people around the world expect it to be safe to drink and to supply many of their drinking water sources,” he continues.
The Stockholm University team has carried out laboratory and field work on the presence and atmospheric transport of PFA over the last decade. They have found that the levels of some harmful PFAs in the atmosphere are not falling markedly, even though their main manufacturer, 3M, phased them out two decades ago.
Why are there PFAS in the Earth’s atmosphere?
PFAs are known to be very persistent, but their continued presence in the atmosphere is also due to their properties and the natural processes that continually return PFAs to the atmosphere from the surface environment.
One of the most important natural processes in the PFA cycle is the transport of seawater into marine air by marine aerosols, which is another active research area for the Stockholm University team.
“The extreme persistence and continuous global cycling of certain PFAs will lead to continued exceedance of the aforementioned guidelines,” says Professor Martin Scheringer, co-author of the study based at ETH Zurich, Switzerland, and RECETOX, University of Zurich.
“So now, due to the global spread of PFAs, environmental media everywhere will exceed environmental quality guidelines designed to protect human health and we will be able to do very little to reduce PFA pollution,” he says. “In other words, it makes sense to define a specific planetary limit for PFAS and, as we conclude in the paper, this limit has already been exceeded,” he adds.
PFAs are a collective name for perfluorinated and polyfluorinated alkyl substances or highly fluorinated substances that have a similar chemical structure. All PFAs are either extremely persistent in the environment or break down into extremely persistent PFAs, earning them the nickname ‘forever chemicals’.
These substances have been linked to a wide range of serious health harms, including cancer, learning and behavior problems in children, infertility and pregnancy complications, increased cholesterol, and immune system problems.