Enhanced toxicity effects of iron particles together with PFOA in drinking water

Iron particles present in drinking water distribution systems (DWDSs) could cause discoloration, while organic pollutants in DWDSs, such as perfluorooctanoic acid (PFOA), could be enriched by iron particles. However, little is known about the enhanced effects of PFOA and iron particles in DWDSs. To fill in these knowledge gaps, herein, iron-PFOA (FEP) particles were generated using residual chlorine as an oxidant in drinking water con-ditions and then separated into different sizes (ranging from small to large: FEP-S, FEP-M ,and FEP-L). FEP-S harbored the greatest cytotoxicity among the sizes. Interestingly, our data revealed that the PFOA released from FEP particles transformed into PFOS (perfluorooctane sulfonate) upon digestion in the gastrointestinal envi-ronment (GI), and FEP-L bored the strongest transformation, showing a toxicity profile that was distinct from that of FEP-S. Furthermore, mechanistic studies revealed that FEP per se should be accountable for the con-version of PFOA to PFOS dependent on the generation of hydroxyl radicals (center dot OH) in GI, and that FEP-L revealed the greatest production of center dot OH. Collectively, these results showed how iron particles and PFOA could result in enhanced toxicity effects in drinking water: (i) PFOA could increase the toxicity of iron particles by reducing particle size and inducing higher generation of center dot OH; (ii) iron particles could induce the transformation of PFOA into more toxic PFOS through digestion.

Automated summary

This study investigated the enhanced toxicity effects of iron particles and PFOA in drinking water. The results demonstrated that PFOA could increase the toxicity of iron particles by reducing particle size and inducing higher generation of hydroxyl radicals, while iron particles could induce the transformation of PFOA into more toxic PFOS through digestion.