Chance finding by Canadian academics working with US EPA

Read the full article by Dr. Emma Davies (Chemical Watch)

“Non-fluorinated ionic surfactants used as ‘environmentally safe”‘alternatives to per and polyfluoroalkyl substances (PFASs) may themselves be toxic, according to a chance finding by Canadian academics working with scientists from the US EPA.

The team made the finding while trialling its new high-throughput technique for prioritising PFASs for further testing, based on how they bind to a key protein. Prioritising a large number of PFASs using traditional bioassays is both costly and time-consuming. In silico toxicity predictions are “promising”, but their accuracy with unknown PFASs is challenged by the substances’ diverse structures, say the researchers.

The new method is based on the way PFASs bind to liver fatty-acid binding protein (L-FABP). The protein plays an ‘essential role’ in determining how the substances bioaccumulate in organisms, with some binding more strongly than others, say the researchers.

A team led by Hui Peng from the University of Toronto used a technique called size-exclusion chromatography co-elution (SECC), followed by mass spectrometry, to analyse 74 PFAS standards provided by the US EPA, as well as a commercial aqueous film forming foam (AFFF) used in fire-fighting products. They also analysed AFFF-contaminated water from Lake Niapenco in Hamilton, Canada.

Of the 74 PFAS samples, nine had a high binding affinity for L-FABP, including “classic” PFASs, such as PFOS and PFOA. Meanwhile, PFOS and perfluorohexane sulfonate (PFHxS) were the two most abundant L-FABP-binding substances in the commercial AFFF product.

Unexpected non-fluorinated results

The study revealed the existence of many previously unknown AFFF-derived PFAS substances that bind to L-FABP, described as ‘ligands’. ‘Unexpectedly’, it identified non-fluorinated AFFF chemicals as an ‘even bigger class’ of L-FABP ligands, report the researchers in the journal Environmental Science and Technology…”