Institute of General Organic Chemistry (IQOG-CSIC)

A "large fraction" of groundwater samples are contaminated by perfluoroalkyl and polyfluoroalkyl substances (PFASs) and would be considered unacceptable for drinking water, a study claims. The analysis, published by Nature Geoscience, brings together data from 273 studies of surface and groundwater samples from around the world since 2004. The exact proportion of samples exceeding the thresholds varies according to the standards considered. For example, 69% of groundwater samples with no known source of contamination exceed the Canadian threshold, but the figure is only 6% if the EU criterion for the sum of all PFASs is considered.