We all know by now that PFAS are highly persistent in the environment and can be harmful to both ecosystems and human health. Because PFAS are so difficult to break down, understanding how they move from soil to water is crucial for assessing risks and managing contaminated sites.

This article evaluates how well standardised ISO leaching tests work for measuring the leaching and partitioning of PFAS in soils. The researchers compared two main ISO test methods: a batch test and an up-flow percolation test, using both real-world contaminated soil and soils spiked with different PFAS compounds. They found that the batch test reached equilibrium quickly and gave similar results for short-chain PFAS in both demineralized water and calcium chloride solutions. However, for long-chain PFAS, the solubility was lower in calcium chloride, likely due to changes in how these molecules interact with soil particles.

The up-flow percolation test showed that short-chain PFAS leach out quickly, while long-chain PFAS are released more slowly or remain in the soil. The study also found that the way PFAS partition between soil and water can vary greatly depending on the specific compound, and that calculating these values from leaching tests can be tricky and sometimes uncertain.

Overall, the article concludes that while ISO leaching tests are useful tools for assessing PFAS mobility in soils, they have limitations and may not always reflect real-world conditions. More research and refinement of these methods are needed to improve the accuracy of PFAS risk assessments and to better protect the environment and public health.

For more details, you can read the full article here.