Even in the most remote parts of the world, levels of so-called “forever chemicals” in the atmosphere have become so high that rainwater is now “unsafe to drink” according to recently released water quality guidelines.
Forever chemicals are a group of dangerous man-made products known as PFAS, which stand for perfluoroalkyl or polyfluoroalkyl substances, some of which have been linked to human cancer.
In recent decades, they have spread globally through waterways, oceans, soil and the atmosphere, and as a result they can now be found in rainwater and snow in even the most remote places on Earth – from Antarctica to the Tibetan Plateau, scientists have said. .
Guideline values for PFAS in drinking water, surface water and soil have been dramatically revised due to greater understanding of their toxicity and the threats they pose to health and nature.
These changes mean that levels of these chemicals in rainwater “are now ubiquitous above guideline levels”, according to researchers from Stockholm University and ETH Zurich University.
“There has been an astonishing decline in guideline values for PFAS in drinking water over the past 20 years,” said Ian Cousins, lead author of the study and professor in the Department of Environmental Sciences at Stockholm University.
“For example, the drinking water guideline value for one well-known substance in the PFAS class, namely the carcinogenic perfluorooctanoic acid (PFOA), has decreased by 37.5 million times in the United States.”
He added: “Based on the latest US guidelines for PFOA in drinking water, rainwater everywhere would be considered unsafe to drink.”
Although in the industrialized 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 distribution of these chemicals, the Stockholm University team has been conducting laboratory and field work 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 decreasing much despite being phased out by the major manufacturer, 3M, already two decades ago.
PFAS are known to be highly persistent – hence known as “forever chemicals”, but their continued presence in the atmosphere is also due to their properties and natural processes that continuously cycle PFAS back into the atmosphere from the surface environment.
An important way in which PFAS is continuously cycled into the atmosphere is through transport from seawater to marine air with sea spray aerosols, which is another active area of research for the team at Stockholm University.
“The extreme persistence and continuous global cycling of certain PFASs will lead to continued exceedances of [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, because of 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 PFAS contamination.
He added: “In other words, it makes sense to define a planetary limit specifically for PFAS, and as we conclude in the paper, this limit has now been exceeded.”
The research team noted that PFAS have been associated with a wide range of serious health harms, including cancer, learning and behavioral problems in children, infertility and pregnancy complications, increased cholesterol and problems with the immune system.
Dr Jane Muncke, chief executive of the Food Packaging Forum Foundation in Zurich, Switzerland, who was not involved in the research, said: “It cannot be that a few benefit financially while polluting the drinking water of millions of others, causing serious health . problems.”
The enormous sums it will cost to reduce PFAS in drinking water to levels that are safe based on current scientific understanding must be paid for by the industries that produce and use these toxic chemicals. The time to act is now.” The research is published as a perspective article in the journal Environmental science and technology.