PFAS; Precursors; Hepatocytes; Lipid; Accumulation; Induce
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Poly- and Perfluoroalkyl substances (PFASs) are a class of man-made chemicals that are used commonly in household and consumer items. They are found in Teflon^TM cookware, because they deter water, grease, and oil; fluorochemicals have proven useful for a variety of manufacturing processes. The important subgroup is the perfluoroalkyl acids (PFAAs), which include perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). PFOS and PFOA in rodents and monkeys have been shown to increase liver weights and cause fat to accumulate in the liver, or liver steatosis. PFAS have their own health and safety concerns, but a much less researched topic are the precursors to PFAS. Many of these precursors, such as alcohols, and amides, can be degraded to PFAA. The precursors, specifically volatile ones, can be found throughout indoor environments, including households. They are primarily found in these places due to unreacted monomer residues of side chain fluorinated polymers from typical consumer products. The precursors are mainly degraded to PFAA, which is currently one of the main sources of PFAS and PFAA in the environment and households. The precursors that were tested on are: perfluorooctane sulfonamide (FOSA), n-methylperfluoro-1-octanesulfonamide (MetFOSA), n-ethylperfluoro-1-octanesulfonamide (EtFOSA), 1 H, 1 H, 2 H, 2 H-perfluorooctane sulfonic acid (6:2 FTS), perfluoro-n-pentanoic acid (PFPeA (C5)), perfluoro-n-tridecanoic acid (PFTrDA (C13)), and perfluoro-n-tetradecanoic acid (PFTeDA (C14)). Little is known about other PFAS and newer shorter carbon chain length compounds that are being used to replace the original PFAS compounds since they are supposed to be better for humans and the environment. However, not enough testing has been done to prove this, and so we wanted to test these new PFAS replacements to see if they are as toxic or even more toxic than the original PFAS compounds. Based on our preliminary data, which shows that some PFAAs induce lipid deposition in hepatocytes based on chain length and functional groups, we decided that the next experiment should test PFAS precursors. Therefore, we hypothesized that the newer emerging PFASs may also have a capacity to induce lipid accumulation than legacy PFAAs. Since the experiment will be about testing the novel endpoint with emerging PFASs that are replacing widely used PFAAs, there will be three different types of procedures being used- hepatocyte treatments, nile red staining, and gene expression measurements. This study showed that there was no significance compared to the control dimethyl sulfoxide (DMSO) group. There was only significance for the positive control sodium palmate oleate P/O and one treatment group which was the 0.25 μM PFTeDA (C14). Based on the fold changes, most PFAS precursors induced lipid accumulation in hepatocytes. This was determined after calculating the fold changes and seeing that more than half of the PFAS precursors had fold changes of more than 1 meaning that the lipid has been increased.
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