Per- and polyfluoroalkyl substances (PFAS) – also known as “forever chemicals” – are highly persistent human-made hazardous chemicals, which are currently spread globally in the atmosphere, and can be found in rainwater and snow in even the most remote locations on our planet. These chemicals have been associated with a range of serious health issues, including cancers, behavioral and learning problems in children, increased cholesterol, immunity problems, and infertility and pregnancy complications.
During the past two decades, guideline values for PFAS in drinking water, surface waters, and soils have decreased dramatically due to new insights into their extreme toxicity. According to a recent study led by Stockholm University and ETH Zurich, the current levels of PFAS in environmental media are now ubiquitously above guideline levels, defining a new planetary boundary for novel entities that has been exceeded.
“There has been an astounding decline in guideline values for PFAS in drinking water in the last 20 years. 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 U.S.” said study lead author Ian Cousins, a professor of Environmental Science at Stockholm.
“Based on the latest U.S. 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.”
By conducting laboratory and field work on the atmospheric presence and transport of PFAS for the past decade, Professor Cousins and his colleagues have found that the atmospheric levels of some of these chemicals are not declining notably, despite their phase out by several major manufacturers. Besides being highly persistent, their continued presence in the atmosphere is also due to natural processes that continually cycle them back to the atmosphere from the surface environment, such as the transport from seawater to marine air by sea spray aerosols.
“The extreme persistence and continual global cycling of certain PFAS will lead to the continued exceedance of the above-mentioned guidelines,” said study co-author Martin Scheringer, a professor of Environmental Science at ETH 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 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.”
The study is published in the journal Environmental Science & Technology.