Short-chain PFAS: A global challenge - Environmental fate, health risks, and promising removal technologies
Uthradevi Kannan, Manthiram Karthik Ravichandran, Manogharan Monisha, Sivagami Krishnasamy, Valliammai, P. Prabakar, Divya Darshini, Ganesan Sunantha
Abstract
The global shift from long-chain to short-chain per - and polyfluoroalkyl substances (PFAS) has been driven by increasing regulatory restrictions on legacy compounds like perfluorooctanoic acid (PFOA) and perfluoro-octane sulfonic acid (PFOS). It is attributable to their environmental persistence and association with negative health effects. Short-chain PFAS were initially considered safer alternatives, owing to their lower bioaccumulation potential. However, emerging evidence shows that their higher water solubility, lower sorption affinity, and greater mobility enable them to disperse in the environment systems, reaching surface waters, groundwater, etc. Despite their widespread use, short-chain PFAS remain underrepresented in both regulatory frameworks and treatment strategies. Most available remediation techniques including activated carbon adsorption, membrane filtration, and ion exchange, are optimized for longer-chain compounds, and often show limited effective for these smaller and highly mobile PFAS. This review aims to bridge the critical knowledge gaps through focussed evaluation of selected short-chain PFAS, including perfluorobutanoic acid (PFBA), perfluorobutane sulfonic acid (PFBS), perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), and perfluoropentane sulfonic acid (PFPeS). It examines their sources, environmental occurrence, transport mechanisms, and persistence across various matrices, alongside current toxicological findings and human exposure pathways. Finally, it assesses existing treatment technologies and identifies research gaps which need to be explored. Considering the increasing amount of short-chain PFAS and their uncertain long-term impacts, this review advocates for a more precautionary approach. By integrating current scientific knowledge, this review supports the development of more robust policies and targeted remediation strategies for the short-chain PFAS contamination.