Outside the Safe Operating Space of a New Planetary Boundary for Per- and Polyfluoroalkyl Substances (PFAS)

It is hypothesized that environmental contamination by
per- and
polyfluoroalkyl substances (PFAS) defines a separate planetary boundary
and that this boundary has been exceeded. This hypothesis is tested
by comparing the levels of four selected perfluoroalkyl acids (PFAAs)
(i.e., perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid
(PFOA), perfluorohexanesulfonic acid (PFHxS), and perfluorononanoic
acid (PFNA)) in various global environmental media (i.e., rainwater,
soils, and surface waters) with recently proposed guideline levels.
On the basis of the four PFAAs considered, it is concluded that (1)
levels of PFOA and PFOS in rainwater often greatly exceed US Environmental
Protection Agency (EPA) Lifetime Drinking Water Health Advisory levels
and the sum of the aforementioned four PFAAs (Σ4 PFAS) in rainwater
is often above Danish drinking water limit values also based on Σ4
PFAS; (2) levels of PFOS in rainwater are often above Environmental
Quality Standard for Inland European Union Surface Water; and (3)
atmospheric deposition also leads to global soils being ubiquitously
contaminated and to be often above proposed Dutch guideline values.
It is, therefore, concluded that the global spread of these four PFAAs
in the atmosphere has led to the planetary boundary for chemical pollution
being exceeded. Levels of PFAAs in atmospheric deposition are especially
poorly reversible because of the high persistence of PFAAs and their
ability to continuously cycle in the hydrosphere, including on sea
spray aerosols emitted from the oceans. Because of the poor reversibility
of environmental exposure to PFAS and their associated effects, it
is vitally important that PFAS uses and emissions are rapidly restricted.