Even in the most remote parts of the world, the level of so-called “forever chemicals” in the atmosphere has become so high that rainwater is now “unsafe to drink” according to newly released water quality guidelines.
Forever chemicals are a group of man-made hazardous products known as PFAS, which stands for perfluoroalkyl or polyfluoroalkyl substances, some of which are linked to cancer in humans.
In recent decades they have spread globally through water courses, oceans, soils and the atmosphere and as a result, they can now be found in the rainwater and snow in even the most remote locations on Earth – from Antarctica to the Tibetan Plateau, researchers have said.
Guideline values for PFAS in drinking water, surface waters and soils have been revised down dramatically due to greater understanding into their toxicity and the threats they pose to health and the natural world.
The changes mean the levels of these chemicals in rainwater “are now ubiquitously above guideline levels”, according to researchers from Stockholm University and ETH Zurich university.
“There has been an astounding decline in guideline values for PFAS in drinking water in the last 20 years,” said Ian Cousins, the lead author of the study and professor at the Department of Environmental Science at Stockholm University.
“For example, the drinking water guideline value for one well-known substance in the PFAS class, namely the cancer-causing perfluorooctanoic acid (PFOA), has declined by 37.5 million times in the US.”
He added: “Based on the latest US guidelines for PFOA in drinking water, rainwater everywhere would be judged unsafe to drink.“
“Although in the industrial world we don’t often drink rainwater, many people around the world expect it to be safe to drink and it supplies many of our drinking water sources,” Professor Cousins said.
To study the prevalence of these chemicals the Stockholm University team have conducted laboratory and fieldwork on the atmospheric presence and transport of PFAS for the past decade.
They have found that the levels of some harmful PFAS in the atmosphere are not declining notably despite their phase out by the major manufacturer, 3M, already two decades ago.
PFAS are known to be highly persistent – hence being known as “forever chemicals” – but their continued presence in the atmosphere is also due to their properties and natural processes that continually cycle PFAS back to the atmosphere from the surface environment.
A key way PFAS are continually cycled into the atmosphere is through the transport from seawater to marine air by sea spray aerosols, which is another active research area for the Stockholm University team.
“The extreme persistence and continual global cycling of certain PFAS will lead to the continued exceedance of the [water quality] guidelines,” said Professor Martin Scheringer, a co-author of the study and based at ETH Zurich in Switzerland and Masaryk University in the Czech Republic.“
“So now, due to the global spread of PFAS, environmental media everywhere will exceed environmental quality guidelines designed to protect human health and we can do very little to reduce the PFAS contamination.”
“In other words, it makes sense to define a planetary boundary specifically for PFAS and, as we conclude in the paper, this boundary has now been exceeded,” he added.
The research team noted that PFAS have been associated with a wide range of serious health harms, including cancer, learning and behavioural problems in children, infertility and pregnancy complications, increased cholesterol, and immune system problems.
Dr Jane Muncke, managing director of the Food Packaging Forum Foundation in Zurich, who was not involved in the research, said: “It cannot be that some few benefit economically while polluting the drinking water for millions of others, and causing serious health problems.“
The vast amounts that it will cost to reduce PFAS in drinking water to levels that are safe based on current scientific understanding need to be paid by the industry producing and using these toxic chemicals. The time to act is now.”
The research is published as a perspective article in the journal Environmental Science & Technology.