‘Forever chemicals’ can ‘boomerang’ from ocean waves to shore: study

Many of the “forever chemicals” that end up in the ocean can “boomerang back to shore” after crashing waves reemit the compounds into the air, a new study has found.

This “sea-to-air transport” mechanism is polluting the air in coastal regions with toxic compounds called PFAS, according to the study, published in Environmental Science & Technology on Wednesday.

PFAS — per-and polyfluoroalkyl substances — include thousands of toxic compounds linked to kidney, liver, immunological, developmental and reproductive issues. Although present in a variety of household products, such as nonstick pans, cosmetics and food packaging, PFAS are most notorious for contaminating groundwater systems via firefighting foams and industrial discharge.

“The common belief was that PFAS would eventually wash off into the oceans where they would stay to be diluted over the timescale of decades,” Matthew Salter, a co-author of the study and researcher in Stockholm University’s Department of Environmental Science, said in a statement. “But it turns out that there’s a boomerang effect, and some of the toxic PFAS are re-emitted to air, transported long distances and then deposited back onto land.”

While previous simulations conducted in the same laboratory had indicated that sea spray aerosol could be an important source of PFAS in the atmosphere, the new findings provided clear evidence to demonstrate that this hypothesis was true, according to the authors.

From 2018 to 2020, the researchers collected regular aerosol samples from two Norwegian coastal locations: Andøya, an Arctic island in the Vesterålen archipelago, and Birkenes, a municipality located along Norway’s southernmost tip.

They then measured for the presence of perfluoroalkyl acids (PFAAs), a subset of PFAS, as well as sodium ions, which are markers of sea spray aerosol. Among PFAAs are two of the most well-known types of forever chemicals, PFOA and PFOS.

The scientists found significant correlations between the presence of PFAAs and sodium ions in both areas — although these links were generally stronger in the Andøya samples than in those from Birkenes, which is farther from the coast and closer to urban areas, according to the study.

“The results are fascinating but at the same time concerning,” study lead authority Bo Sha, also from Stockholm University, said in a statement.

The strong link between PFAAs and sodium ions in samples from both coastal sites suggest that sea spray aerosol is likely an integral source of air pollution in these regions, the study concluded. Meanwhile, because sea spray aerosol particles can travel significant distances in the atmosphere, the findings suggest that the transport of these compounds “may impact large areas of inland Europe and other continents in addition to coastal areas,” the authors added.

“It is possible that atmospherically deposited PFAS could contaminate coastal drinking water sources for the foreseeable future,” Ian Cousins, another co-author from Stockholm University, said in a statement.

“Our study gives a new dimension to the meaning of the term forever chemicals.” Cousins added. “Even the PFAS we thought would be lost to the sea boomerang back for us to be exposed all over again.”